[1] A photoelectric cell converts –
A.
Mechanical energy to electric energy
B.
Heat energy to mechanical energy
C.
Light energy to chemical energy
D.
Light energy to electrical energy
Ans:
Light energy to electrical energy
Explanation :
Photoelectric cell or photocell, device whose electrical characteristics (e.g., current, voltage, or resistance) vary when light is incident upon it. The most common type consists of two electrodes separated by a light-sensitive semiconductor material.
[2] The temperature of a body is an indicator of –
A.
The total energy of the molecules of the body
B.
The average energy of the molecules of the body
C.
The total velocity of the molecules of the body
D.
The average kinetic energy of the molecules of the body
Ans:
The average kinetic energy of the molecules of the body
Explanation :
0
[3] Two stones of different masses are dropped simultaneously from the top of a building –
A.
Smaller stone reaches the ground earlier
B.
Larger stone reaches the ground earlier
C.
Both the stones reach the ground at the same time
D.
Depends on the composition of the stone
Ans:
Both the stones reach the ground at the same time
Explanation :
Both stones at the same Lime. The initial speed is 0 for both stones, and the only acceleration working in that system would be g (Gravity acceleration). So, as the distance is the same, the final speed will be the same time. The only reason which could change this result is a difference in the shape of the stones. While they fall to the ground, they must "open" a way across the air. The shape of the falling object will decide the force needed to open that way.
[4] Rainbow is due to -
A.
absorption of sunlight in minute water droplets
B.
diffusion of sunlight through water droplets
C.
ionisation of water deposits
D.
refraction and reflection of sunlight by water droplets
Ans:
refraction and reflection of sunlight by water droplets
Explanation :
[5] Condensation process refers to :
A.
Conversion of water into water vapour
B.
Conversion of water vapour into solid form
C.
Conversion of water into solid form
D.
Conversion of water vapour into its liquid form
Ans:
Conversion of water vapour into its liquid form
Explanation :
Condensation is the change of the physical state of matter from gas phase into liquid phase. It is also defined as the change in the state of water vapour to liquid water when in contact with a liquid or solid surface.
[6] If a band is played on the moon the sound will -
A.
reverberate
B.
be heard by us faintly
C.
be heard upto 10km from it
D.
not be heard at any distance at all from it
Ans:
not be heard at any distance at all from it
Explanation :
As there is no atmosphere surrounding the moon, the sound from any band that is played there cannot travel outwards there is no material medium surrounding it for its propagation.
[7] In a water lifting electric pump, We convert –
A.
Electrical energy into Potential energy
B.
Kinetic energy into Electrical energy
C.
Kinetic energy into Potential energy
D.
Electrical energy into Kinetic energy
Ans:
Electrical energy into Potential energy
Explanation :
In a water lifting electric pump, we convert electrical energy into potential energy. In hydraulic pump mechanical energy in converted into potential energy
[8] An electron microscope gives higher magnification than an optical microscope, because:
A.
It uses more powerful lenses
B.
the velocity of electron is smaller than that of visible
C.
the electrons have more energy than the light particles
D.
the wavelength of electrons is smaller as compared to the wavelength of visible light
Ans:
the wavelength of electrons is smaller as compared to the wavelength of visible light
Explanation :
An electron microscope uses a beam of electrons to illuminate a specimen and produce a magnified image. An electron microscope (EM) has greater resolving power than a light-powered optical microscope because electrons have wavelengths about 100,000 times shorter than visible light photons. Magnification is the process of enlarging something only in appearance, not in physical size.
[9] We always see the same lace of the moon, because –
A.
It is smaller than the earth
B.
It revolves on its axis in a direction opposite to that of the earth
C.
It takes equal time for revolution around the earth and rotation on its own axis
D.
It rotates at the same speed as the earth around the sun
Ans:
It takes equal time for revolution around the earth and rotation on its own axis
Explanation :
It is tidal locking that causes the synchronous rotation which causes the Moon to present "just one side" to the Earth all the time. The Moon rotates (spins) but very slowly, making one turn on its axis in the same time it takes to revolve (orbit) around the Earth. So it maintains a "constant face" in our direction.
[10] Which of the following laws validates the statement that matter can neither be created nor destroyed?
A.
Law of conservation of energy
B.
Le Chatelier's Principle
C.
Law of conservation of mass
D.
Law of osmosis
Ans:
Law of conservation of mass
Explanation :
The law of conservation of mass, also known as the principle of mass/matter conservation, states that the mass of an isolated system (closed to all transfers of matter and energy) will remain constant over time. This principle is equivalent to the conservation of energy: when energy or mass is enclosed in a system and none is allowed in or out, its quantity cannot otherwise change over time (hence, its quantity is "conserved" over time).
[11] What is viewed through an electron microscope?
A.
Electrons and other elementary particles
B.
Structure of bacteria and viruses
C.
Inside of human stomach
D.
Inside of the human eye
Ans:
Structure of bacteria and viruses
Explanation :
Electron microscopes are used to observe a wide range of biological and inorganic specimens including microorganisms, cells, large molecules, biopsy samples, metals, and crystals. An electron microscope uses a beam of electrons to illuminate a specimen and produce a magnified image. An electron microscope (EM) has greater resolving power than a light-powered optical microscope because electrons have wavelengths about 100,000 times shorter than visible light photons.
[12] Rain drops fall from great height. Which among the following statements is true regarding it?
A.
they fall with that ultimate velocity, which are different for different droplets
B.
they fall with same ultimate velocity
C.
their velocity increases and they fall with different velocity on the earth
D.
their velocity increases and they fall with same velocity on the earth
Ans:
they fall with that ultimate velocity, which are different for different droplets
Explanation :
Any mass is attracted to the Earth by the pull of gravity. Gravity accelerates all objects towards the ground at a specific rate. Without any other forces present, the speed of an object in free fall will increase the farther or longer it falls. In general the air resistance on an object depends upon several variables. First, it depends upon the shape of the object. Its shape determines the object's drag coefficient: the more aerodynamic the shape, the less drag. Second, it depends upon the size of the object; specifically the cross-sectional area presented to the airflow (perpendicular to the direction of travel).
[13] Which of the following occurred first?
A.
Albert Einstein propounded the General Theory of Relativity
B.
Max Planck unveiled the Quantum Theory
C.
Guglielmo Marconi sent out the first wireless signals
D.
Wright Brothers successfully flew an aircraft
Ans:
Guglielmo Marconi sent out the first wireless signals
Explanation :
Guglielmo Marconi sent out the first wireless signals. In the early summer of 1895 and despite an intervening hill, Marconi achieved signal transmission and reception over a distance of about 2km. Success was indicated initially by the waving of a handkerchief and progressed to the need to fire a gun. The theory of relativity transformed theoretical physics and astronomy during the 20th century.
[14] Why does bleeding occur through the nose in high mountainous regions?
A.
The pressure of blood in capillaries is greater than the outside pressure
B.
The pressure at high altitudes is greater than that on the plains
C.
The blood pressure of a person increases at high altitudes
D.
The blood pressure fluctuates and finally decreases drastically
Ans:
The blood pressure of a person increases at high altitudes
Explanation :
Nose bleeds can occur at high altitudes. The bleeding may be caused by the change in air pressure associated with the change in altitude or the cold dry air common at high altitudes. No matter the cause, the symptoms and treatment of a high altitude bloody nose are the same. A nose bleed is defined as the discharge of blood from the nostrils. Stress and anxiety raises the blood pressure, complicating the nose bleed.
[15] Pipelines in cold countries often burst in winter, because –
A.
Water freezes and expands in its volume
B.
Temperature of ice is less than that of water
C.
Pipelines contract in their volume
D.
Pipelines expand due to freezing
Ans:
Water freezes and expands in its volume
Explanation :
Water expands on freezing. When liquid water is cooled, it contracts like one would expect until a temperature of approximately 4 degrees Celsius is reached. After that, it expands slightly until it reaches the freezing point, and then when it freezes it expands by approximately 9%. The fact that water expands upon freezing causes icebergs to float.
[16] The modulus of rigidity is the ratio of –
A.
Longitudinal stress to longitudinal strain
B.
Volume stress to volume strain
C.
Shearing stress to shearing strain
D.
Tensile stress to tensile strain
Ans:
Shearing stress to shearing strain
Explanation :
In materials science, shear modulus or modulus of rigidity, denoted by G, or sometimes S, is defined as the ratio of shear stress to the shear strain. The shear modulus describes the material's response to shearing strains (like cutting it with dull scissors). The shear modulus is concerned with the deformation of a solid when it experiences a force parallel to one of its surfaces while its opposite face experiences an opposing force (such as friction). In the case of an object that's shaped like a rectangular prism, it will deform into a parallelepiped.
[17] In heating frozen foods in sealed pouches in microwaves, why do you first poke holes in the pouch?
A.
To prevent the steam pressure from bursting open the pouch
B.
To allow the heat to get into the food through the hole
C.
To allow the microwaves to get into the food through the holes
D.
To allow the aroma of the food to come out through the holes
Ans:
To prevent the steam pressure from bursting open the pouch
Explanation :
Anything in a tight skin or shell can explode in a microwave because the water inside can expand and burst through. It is for this very reason that before microwaving, the skin of potatoes should be pricked, winter squash and similar vegetables should be cut in half, eggs should be taken out of shells and holes should be poked in the plastic wrap or sealed pouches of frozen packaged foods.
[18] A sphere rolls down on two inclined planes of different angles but same height, it does so –
A.
in the same time
B.
with the same speed
C.
in the same time with the same speed
D.
in the same time with the same kinetic energy
Ans:
with the same speed
Explanation :
The velocity of the sphere at the bottom depends only on height and acceleration due to gravity. Both these values are constants. Therefore, the velocity at the bottom remains the same whichever inclined plane the sphere is rolled. However, the sphere will take longer time to reach the bottom of the inclined plane having the smaller inclination. The kinetic energy will be the same. What will differ is time taken to reach the bottom.
[19] During hot weather, the fan produces a feeling of comfort. This is because –
A.
fan supplies cool air
B.
fan cools the air
C.
our perspiration evaporates rapidly
D.
conductivity of air increases
Ans:
our perspiration evaporates rapidly
Explanation :
Fans make the air more comfortable for two reasons: (1) by moving the air, they blow away body heat and evaporate sweat, cooling the body, and (2) they also mix the cooler air near the floor with the warmer air by people's faces.
[20] Stars appears to move from east to west because -
A.
all stars move from east to west
B.
the earth rotates from west to east
C.
the earth rotates from east to west
D.
the background of the stars moves from west to east
Ans:
the earth rotates from west to east
Explanation :
Earth's spin (or rotation) on its axis. Earth rotates or spins toward the east, and that's why the Sun, Moon, planets, and stars all rise in the east and make their way westward across the sky.
[21] An egg sinks in soft water but floats in a concentrated solution of salt because –
A.
Egg absorbs salt from the solution and expands
B.
Albumin dissolves in salt solution and egg becomes lighter
C.
The density of salt solution exceeds the density of eggs
D.
Water has high surface tension
Ans:
The density of salt solution exceeds the density of eggs
Explanation :
Following the density principle, the density of the egg compared to the density of the tap water is lesser (the density principle states that an object or substance with lesser density will float on the surface of the substance or object which has the greater density). Now, with salt, salt makes the density of the tap water to increase and increases also the salinity of the water making the egg float because the density of the water with salt is now greater than the density of the egg and that is why an egg sinks in soft water but floats in a concentrated solution of salt.
[22] A hydrogen balloon floats because of –
A.
Air pressure decreases with decrease in height
B.
Air pressure decreases with decrease in weight
C.
Weight of the balloon is less than the weight of air displaced by it
D.
The pressure inside the balloon is more than the pressure outside it
Ans:
Weight of the balloon is less than the weight of air displaced by it
Explanation :
A hydrogen atom is very light. Most of the air on earth is made up of nitrogen, oxygen, and carbon dioxide. All of these elements are heavier than hydrogen, so the balloon is pushed upwards. Hydrogen weighs 0.08988 grams per liter. Nitrogen, which makes up 80% of the air we breathe, weighs 1.2506 grams per liter.
[23] The term ‘equinox’ means –
A.
The path which the Earth takes around the Sun
B.
The axis of the Earth around which it rotates
C.
When the day and night are of equal duration
D.
The time when the Sun seems to be going round and round in the sky in the Arctic but does not go below the horizon
Ans:
When the day and night are of equal duration
Explanation :
The name "equinox" is derived from the Latin aequus (equal) and nox (night), because around the equinox, the night and day have approximately equal length. An equinox occurs twice a year (around 20 March and 22 September), when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator. The term equinox can also be used in a broader sense, meaning the date when such a passage happens.
[24] After long periods of use, a grey spot develops on the inside of a bulb. This is because –
A.
the tungsten filament evaporates and collects there
B.
the heat of the bulb scorches the glass at the top
C.
dust inside the bulb condenses on the top
D.
glass undergoes a change due to the heat
Ans:
dust inside the bulb condenses on the top
Explanation :
At high operating temperatures, tungsten evaporates from the filament and gradually forms a gray film on the inside of the bulb. The inert gas atoms collide with the evaporating tungsten, causing some of the tungsten atoms to return to the filament. Eventually, however, a thin spot develops in the filament. When this happens, the filament will break and the bulb fails.
[25] The blue colour of water in the sea is due to –
A.
absorption of other colours except blue by water molecules
B.
scattering of blue light by water molecules
C.
reflection of blue light by impurities in sea water
D.
reflection of blue sky by sea water
Ans:
absorption of other colours except blue by water molecules
Explanation :
Almost all sunlight that enters the ocean is absorbed, except very close to the coast. The red, yellow, and green wavelengths of sunlight are absorbed by water molecules in the ocean. The reason the ocean is blue is due to the absorption and scattering of light. The blue wavelengths of light are scattered, similar to the
Explanation :
Photoelectric cell or photocell, device whose electrical characteristics (e.g., current, voltage, or resistance) vary when light is incident upon it. The most common type consists of two electrodes separated by a light-sensitive semiconductor material.
[2] The temperature of a body is an indicator of –
A.
The total energy of the molecules of the body
B.
The average energy of the molecules of the body
C.
The total velocity of the molecules of the body
D.
The average kinetic energy of the molecules of the body
Ans:
The average kinetic energy of the molecules of the body
Explanation :
0
[3] Two stones of different masses are dropped simultaneously from the top of a building –
A.
Smaller stone reaches the ground earlier
B.
Larger stone reaches the ground earlier
C.
Both the stones reach the ground at the same time
D.
Depends on the composition of the stone
Ans:
Both the stones reach the ground at the same time
Explanation :
Both stones at the same Lime. The initial speed is 0 for both stones, and the only acceleration working in that system would be g (Gravity acceleration). So, as the distance is the same, the final speed will be the same time. The only reason which could change this result is a difference in the shape of the stones. While they fall to the ground, they must "open" a way across the air. The shape of the falling object will decide the force needed to open that way.
[4] Rainbow is due to -
A.
absorption of sunlight in minute water droplets
B.
diffusion of sunlight through water droplets
C.
ionisation of water deposits
D.
refraction and reflection of sunlight by water droplets
Ans:
refraction and reflection of sunlight by water droplets
Explanation :
[5] Condensation process refers to :
A.
Conversion of water into water vapour
B.
Conversion of water vapour into solid form
C.
Conversion of water into solid form
D.
Conversion of water vapour into its liquid form
Ans:
Conversion of water vapour into its liquid form
Explanation :
Condensation is the change of the physical state of matter from gas phase into liquid phase. It is also defined as the change in the state of water vapour to liquid water when in contact with a liquid or solid surface.
[6] If a band is played on the moon the sound will -
A.
reverberate
B.
be heard by us faintly
C.
be heard upto 10km from it
D.
not be heard at any distance at all from it
Ans:
not be heard at any distance at all from it
Explanation :
As there is no atmosphere surrounding the moon, the sound from any band that is played there cannot travel outwards there is no material medium surrounding it for its propagation.
[7] In a water lifting electric pump, We convert –
A.
Electrical energy into Potential energy
B.
Kinetic energy into Electrical energy
C.
Kinetic energy into Potential energy
D.
Electrical energy into Kinetic energy
Ans:
Electrical energy into Potential energy
Explanation :
In a water lifting electric pump, we convert electrical energy into potential energy. In hydraulic pump mechanical energy in converted into potential energy
[8] An electron microscope gives higher magnification than an optical microscope, because:
A.
It uses more powerful lenses
B.
the velocity of electron is smaller than that of visible
C.
the electrons have more energy than the light particles
D.
the wavelength of electrons is smaller as compared to the wavelength of visible light
Ans:
the wavelength of electrons is smaller as compared to the wavelength of visible light
Explanation :
An electron microscope uses a beam of electrons to illuminate a specimen and produce a magnified image. An electron microscope (EM) has greater resolving power than a light-powered optical microscope because electrons have wavelengths about 100,000 times shorter than visible light photons. Magnification is the process of enlarging something only in appearance, not in physical size.
[9] We always see the same lace of the moon, because –
A.
It is smaller than the earth
B.
It revolves on its axis in a direction opposite to that of the earth
C.
It takes equal time for revolution around the earth and rotation on its own axis
D.
It rotates at the same speed as the earth around the sun
Ans:
It takes equal time for revolution around the earth and rotation on its own axis
Explanation :
It is tidal locking that causes the synchronous rotation which causes the Moon to present "just one side" to the Earth all the time. The Moon rotates (spins) but very slowly, making one turn on its axis in the same time it takes to revolve (orbit) around the Earth. So it maintains a "constant face" in our direction.
[10] Which of the following laws validates the statement that matter can neither be created nor destroyed?
A.
Law of conservation of energy
B.
Le Chatelier's Principle
C.
Law of conservation of mass
D.
Law of osmosis
Ans:
Law of conservation of mass
Explanation :
The law of conservation of mass, also known as the principle of mass/matter conservation, states that the mass of an isolated system (closed to all transfers of matter and energy) will remain constant over time. This principle is equivalent to the conservation of energy: when energy or mass is enclosed in a system and none is allowed in or out, its quantity cannot otherwise change over time (hence, its quantity is "conserved" over time).
[11] What is viewed through an electron microscope?
A.
Electrons and other elementary particles
B.
Structure of bacteria and viruses
C.
Inside of human stomach
D.
Inside of the human eye
Ans:
Structure of bacteria and viruses
Explanation :
Electron microscopes are used to observe a wide range of biological and inorganic specimens including microorganisms, cells, large molecules, biopsy samples, metals, and crystals. An electron microscope uses a beam of electrons to illuminate a specimen and produce a magnified image. An electron microscope (EM) has greater resolving power than a light-powered optical microscope because electrons have wavelengths about 100,000 times shorter than visible light photons.
[12] Rain drops fall from great height. Which among the following statements is true regarding it?
A.
they fall with that ultimate velocity, which are different for different droplets
B.
they fall with same ultimate velocity
C.
their velocity increases and they fall with different velocity on the earth
D.
their velocity increases and they fall with same velocity on the earth
Ans:
they fall with that ultimate velocity, which are different for different droplets
Explanation :
Any mass is attracted to the Earth by the pull of gravity. Gravity accelerates all objects towards the ground at a specific rate. Without any other forces present, the speed of an object in free fall will increase the farther or longer it falls. In general the air resistance on an object depends upon several variables. First, it depends upon the shape of the object. Its shape determines the object's drag coefficient: the more aerodynamic the shape, the less drag. Second, it depends upon the size of the object; specifically the cross-sectional area presented to the airflow (perpendicular to the direction of travel).
[13] Which of the following occurred first?
A.
Albert Einstein propounded the General Theory of Relativity
B.
Max Planck unveiled the Quantum Theory
C.
Guglielmo Marconi sent out the first wireless signals
D.
Wright Brothers successfully flew an aircraft
Ans:
Guglielmo Marconi sent out the first wireless signals
Explanation :
Guglielmo Marconi sent out the first wireless signals. In the early summer of 1895 and despite an intervening hill, Marconi achieved signal transmission and reception over a distance of about 2km. Success was indicated initially by the waving of a handkerchief and progressed to the need to fire a gun. The theory of relativity transformed theoretical physics and astronomy during the 20th century.
[14] Why does bleeding occur through the nose in high mountainous regions?
A.
The pressure of blood in capillaries is greater than the outside pressure
B.
The pressure at high altitudes is greater than that on the plains
C.
The blood pressure of a person increases at high altitudes
D.
The blood pressure fluctuates and finally decreases drastically
Ans:
The blood pressure of a person increases at high altitudes
Explanation :
Nose bleeds can occur at high altitudes. The bleeding may be caused by the change in air pressure associated with the change in altitude or the cold dry air common at high altitudes. No matter the cause, the symptoms and treatment of a high altitude bloody nose are the same. A nose bleed is defined as the discharge of blood from the nostrils. Stress and anxiety raises the blood pressure, complicating the nose bleed.
[15] Pipelines in cold countries often burst in winter, because –
A.
Water freezes and expands in its volume
B.
Temperature of ice is less than that of water
C.
Pipelines contract in their volume
D.
Pipelines expand due to freezing
Ans:
Water freezes and expands in its volume
Explanation :
Water expands on freezing. When liquid water is cooled, it contracts like one would expect until a temperature of approximately 4 degrees Celsius is reached. After that, it expands slightly until it reaches the freezing point, and then when it freezes it expands by approximately 9%. The fact that water expands upon freezing causes icebergs to float.
[16] The modulus of rigidity is the ratio of –
A.
Longitudinal stress to longitudinal strain
B.
Volume stress to volume strain
C.
Shearing stress to shearing strain
D.
Tensile stress to tensile strain
Ans:
Shearing stress to shearing strain
Explanation :
In materials science, shear modulus or modulus of rigidity, denoted by G, or sometimes S, is defined as the ratio of shear stress to the shear strain. The shear modulus describes the material's response to shearing strains (like cutting it with dull scissors). The shear modulus is concerned with the deformation of a solid when it experiences a force parallel to one of its surfaces while its opposite face experiences an opposing force (such as friction). In the case of an object that's shaped like a rectangular prism, it will deform into a parallelepiped.
[17] In heating frozen foods in sealed pouches in microwaves, why do you first poke holes in the pouch?
A.
To prevent the steam pressure from bursting open the pouch
B.
To allow the heat to get into the food through the hole
C.
To allow the microwaves to get into the food through the holes
D.
To allow the aroma of the food to come out through the holes
Ans:
To prevent the steam pressure from bursting open the pouch
Explanation :
Anything in a tight skin or shell can explode in a microwave because the water inside can expand and burst through. It is for this very reason that before microwaving, the skin of potatoes should be pricked, winter squash and similar vegetables should be cut in half, eggs should be taken out of shells and holes should be poked in the plastic wrap or sealed pouches of frozen packaged foods.
[18] A sphere rolls down on two inclined planes of different angles but same height, it does so –
A.
in the same time
B.
with the same speed
C.
in the same time with the same speed
D.
in the same time with the same kinetic energy
Ans:
with the same speed
Explanation :
The velocity of the sphere at the bottom depends only on height and acceleration due to gravity. Both these values are constants. Therefore, the velocity at the bottom remains the same whichever inclined plane the sphere is rolled. However, the sphere will take longer time to reach the bottom of the inclined plane having the smaller inclination. The kinetic energy will be the same. What will differ is time taken to reach the bottom.
[19] During hot weather, the fan produces a feeling of comfort. This is because –
A.
fan supplies cool air
B.
fan cools the air
C.
our perspiration evaporates rapidly
D.
conductivity of air increases
Ans:
our perspiration evaporates rapidly
Explanation :
Fans make the air more comfortable for two reasons: (1) by moving the air, they blow away body heat and evaporate sweat, cooling the body, and (2) they also mix the cooler air near the floor with the warmer air by people's faces.
[20] Stars appears to move from east to west because -
A.
all stars move from east to west
B.
the earth rotates from west to east
C.
the earth rotates from east to west
D.
the background of the stars moves from west to east
Ans:
the earth rotates from west to east
Explanation :
Earth's spin (or rotation) on its axis. Earth rotates or spins toward the east, and that's why the Sun, Moon, planets, and stars all rise in the east and make their way westward across the sky.
[21] An egg sinks in soft water but floats in a concentrated solution of salt because –
A.
Egg absorbs salt from the solution and expands
B.
Albumin dissolves in salt solution and egg becomes lighter
C.
The density of salt solution exceeds the density of eggs
D.
Water has high surface tension
Ans:
The density of salt solution exceeds the density of eggs
Explanation :
Following the density principle, the density of the egg compared to the density of the tap water is lesser (the density principle states that an object or substance with lesser density will float on the surface of the substance or object which has the greater density). Now, with salt, salt makes the density of the tap water to increase and increases also the salinity of the water making the egg float because the density of the water with salt is now greater than the density of the egg and that is why an egg sinks in soft water but floats in a concentrated solution of salt.
[22] A hydrogen balloon floats because of –
A.
Air pressure decreases with decrease in height
B.
Air pressure decreases with decrease in weight
C.
Weight of the balloon is less than the weight of air displaced by it
D.
The pressure inside the balloon is more than the pressure outside it
Ans:
Weight of the balloon is less than the weight of air displaced by it
Explanation :
A hydrogen atom is very light. Most of the air on earth is made up of nitrogen, oxygen, and carbon dioxide. All of these elements are heavier than hydrogen, so the balloon is pushed upwards. Hydrogen weighs 0.08988 grams per liter. Nitrogen, which makes up 80% of the air we breathe, weighs 1.2506 grams per liter.
[23] The term ‘equinox’ means –
A.
The path which the Earth takes around the Sun
B.
The axis of the Earth around which it rotates
C.
When the day and night are of equal duration
D.
The time when the Sun seems to be going round and round in the sky in the Arctic but does not go below the horizon
Ans:
When the day and night are of equal duration
Explanation :
The name "equinox" is derived from the Latin aequus (equal) and nox (night), because around the equinox, the night and day have approximately equal length. An equinox occurs twice a year (around 20 March and 22 September), when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator. The term equinox can also be used in a broader sense, meaning the date when such a passage happens.
[24] After long periods of use, a grey spot develops on the inside of a bulb. This is because –
A.
the tungsten filament evaporates and collects there
B.
the heat of the bulb scorches the glass at the top
C.
dust inside the bulb condenses on the top
D.
glass undergoes a change due to the heat
Ans:
dust inside the bulb condenses on the top
Explanation :
At high operating temperatures, tungsten evaporates from the filament and gradually forms a gray film on the inside of the bulb. The inert gas atoms collide with the evaporating tungsten, causing some of the tungsten atoms to return to the filament. Eventually, however, a thin spot develops in the filament. When this happens, the filament will break and the bulb fails.
[25] The blue colour of water in the sea is due to –
A.
absorption of other colours except blue by water molecules
B.
scattering of blue light by water molecules
C.
reflection of blue light by impurities in sea water
D.
reflection of blue sky by sea water
Ans:
absorption of other colours except blue by water molecules
Explanation :
Almost all sunlight that enters the ocean is absorbed, except very close to the coast. The red, yellow, and green wavelengths of sunlight are absorbed by water molecules in the ocean. The reason the ocean is blue is due to the absorption and scattering of light. The blue wavelengths of light are scattered, similar to the
Explanation :
Both stones at the same Lime. The initial speed is 0 for both stones, and the only acceleration working in that system would be g (Gravity acceleration). So, as the distance is the same, the final speed will be the same time. The only reason which could change this result is a difference in the shape of the stones. While they fall to the ground, they must "open" a way across the air. The shape of the falling object will decide the force needed to open that way.
[4] Rainbow is due to -
A.
absorption of sunlight in minute water droplets
B.
diffusion of sunlight through water droplets
C.
ionisation of water deposits
D.
refraction and reflection of sunlight by water droplets
Ans:
refraction and reflection of sunlight by water droplets
Explanation :
[5] Condensation process refers to :
A.
Conversion of water into water vapour
B.
Conversion of water vapour into solid form
C.
Conversion of water into solid form
D.
Conversion of water vapour into its liquid form
Ans:
Conversion of water vapour into its liquid form
Explanation :
Condensation is the change of the physical state of matter from gas phase into liquid phase. It is also defined as the change in the state of water vapour to liquid water when in contact with a liquid or solid surface.
[6] If a band is played on the moon the sound will -
A.
reverberate
B.
be heard by us faintly
C.
be heard upto 10km from it
D.
not be heard at any distance at all from it
Ans:
not be heard at any distance at all from it
Explanation :
As there is no atmosphere surrounding the moon, the sound from any band that is played there cannot travel outwards there is no material medium surrounding it for its propagation.
[7] In a water lifting electric pump, We convert –
A.
Electrical energy into Potential energy
B.
Kinetic energy into Electrical energy
C.
Kinetic energy into Potential energy
D.
Electrical energy into Kinetic energy
Ans:
Electrical energy into Potential energy
Explanation :
In a water lifting electric pump, we convert electrical energy into potential energy. In hydraulic pump mechanical energy in converted into potential energy
[8] An electron microscope gives higher magnification than an optical microscope, because:
A.
It uses more powerful lenses
B.
the velocity of electron is smaller than that of visible
C.
the electrons have more energy than the light particles
D.
the wavelength of electrons is smaller as compared to the wavelength of visible light
Ans:
the wavelength of electrons is smaller as compared to the wavelength of visible light
Explanation :
An electron microscope uses a beam of electrons to illuminate a specimen and produce a magnified image. An electron microscope (EM) has greater resolving power than a light-powered optical microscope because electrons have wavelengths about 100,000 times shorter than visible light photons. Magnification is the process of enlarging something only in appearance, not in physical size.
[9] We always see the same lace of the moon, because –
A.
It is smaller than the earth
B.
It revolves on its axis in a direction opposite to that of the earth
C.
It takes equal time for revolution around the earth and rotation on its own axis
D.
It rotates at the same speed as the earth around the sun
Ans:
It takes equal time for revolution around the earth and rotation on its own axis
Explanation :
It is tidal locking that causes the synchronous rotation which causes the Moon to present "just one side" to the Earth all the time. The Moon rotates (spins) but very slowly, making one turn on its axis in the same time it takes to revolve (orbit) around the Earth. So it maintains a "constant face" in our direction.
[10] Which of the following laws validates the statement that matter can neither be created nor destroyed?
A.
Law of conservation of energy
B.
Le Chatelier's Principle
C.
Law of conservation of mass
D.
Law of osmosis
Ans:
Law of conservation of mass
Explanation :
The law of conservation of mass, also known as the principle of mass/matter conservation, states that the mass of an isolated system (closed to all transfers of matter and energy) will remain constant over time. This principle is equivalent to the conservation of energy: when energy or mass is enclosed in a system and none is allowed in or out, its quantity cannot otherwise change over time (hence, its quantity is "conserved" over time).
[11] What is viewed through an electron microscope?
A.
Electrons and other elementary particles
B.
Structure of bacteria and viruses
C.
Inside of human stomach
D.
Inside of the human eye
Ans:
Structure of bacteria and viruses
Explanation :
Electron microscopes are used to observe a wide range of biological and inorganic specimens including microorganisms, cells, large molecules, biopsy samples, metals, and crystals. An electron microscope uses a beam of electrons to illuminate a specimen and produce a magnified image. An electron microscope (EM) has greater resolving power than a light-powered optical microscope because electrons have wavelengths about 100,000 times shorter than visible light photons.
[12] Rain drops fall from great height. Which among the following statements is true regarding it?
A.
they fall with that ultimate velocity, which are different for different droplets
B.
they fall with same ultimate velocity
C.
their velocity increases and they fall with different velocity on the earth
D.
their velocity increases and they fall with same velocity on the earth
Ans:
they fall with that ultimate velocity, which are different for different droplets
Explanation :
Any mass is attracted to the Earth by the pull of gravity. Gravity accelerates all objects towards the ground at a specific rate. Without any other forces present, the speed of an object in free fall will increase the farther or longer it falls. In general the air resistance on an object depends upon several variables. First, it depends upon the shape of the object. Its shape determines the object's drag coefficient: the more aerodynamic the shape, the less drag. Second, it depends upon the size of the object; specifically the cross-sectional area presented to the airflow (perpendicular to the direction of travel).
[13] Which of the following occurred first?
A.
Albert Einstein propounded the General Theory of Relativity
B.
Max Planck unveiled the Quantum Theory
C.
Guglielmo Marconi sent out the first wireless signals
D.
Wright Brothers successfully flew an aircraft
Ans:
Guglielmo Marconi sent out the first wireless signals
Explanation :
Guglielmo Marconi sent out the first wireless signals. In the early summer of 1895 and despite an intervening hill, Marconi achieved signal transmission and reception over a distance of about 2km. Success was indicated initially by the waving of a handkerchief and progressed to the need to fire a gun. The theory of relativity transformed theoretical physics and astronomy during the 20th century.
[14] Why does bleeding occur through the nose in high mountainous regions?
A.
The pressure of blood in capillaries is greater than the outside pressure
B.
The pressure at high altitudes is greater than that on the plains
C.
The blood pressure of a person increases at high altitudes
D.
The blood pressure fluctuates and finally decreases drastically
Ans:
The blood pressure of a person increases at high altitudes
Explanation :
Nose bleeds can occur at high altitudes. The bleeding may be caused by the change in air pressure associated with the change in altitude or the cold dry air common at high altitudes. No matter the cause, the symptoms and treatment of a high altitude bloody nose are the same. A nose bleed is defined as the discharge of blood from the nostrils. Stress and anxiety raises the blood pressure, complicating the nose bleed.
[15] Pipelines in cold countries often burst in winter, because –
A.
Water freezes and expands in its volume
B.
Temperature of ice is less than that of water
C.
Pipelines contract in their volume
D.
Pipelines expand due to freezing
Ans:
Water freezes and expands in its volume
Explanation :
Water expands on freezing. When liquid water is cooled, it contracts like one would expect until a temperature of approximately 4 degrees Celsius is reached. After that, it expands slightly until it reaches the freezing point, and then when it freezes it expands by approximately 9%. The fact that water expands upon freezing causes icebergs to float.
[16] The modulus of rigidity is the ratio of –
A.
Longitudinal stress to longitudinal strain
B.
Volume stress to volume strain
C.
Shearing stress to shearing strain
D.
Tensile stress to tensile strain
Ans:
Shearing stress to shearing strain
Explanation :
In materials science, shear modulus or modulus of rigidity, denoted by G, or sometimes S, is defined as the ratio of shear stress to the shear strain. The shear modulus describes the material's response to shearing strains (like cutting it with dull scissors). The shear modulus is concerned with the deformation of a solid when it experiences a force parallel to one of its surfaces while its opposite face experiences an opposing force (such as friction). In the case of an object that's shaped like a rectangular prism, it will deform into a parallelepiped.
[17] In heating frozen foods in sealed pouches in microwaves, why do you first poke holes in the pouch?
A.
To prevent the steam pressure from bursting open the pouch
B.
To allow the heat to get into the food through the hole
C.
To allow the microwaves to get into the food through the holes
D.
To allow the aroma of the food to come out through the holes
Ans:
To prevent the steam pressure from bursting open the pouch
Explanation :
Anything in a tight skin or shell can explode in a microwave because the water inside can expand and burst through. It is for this very reason that before microwaving, the skin of potatoes should be pricked, winter squash and similar vegetables should be cut in half, eggs should be taken out of shells and holes should be poked in the plastic wrap or sealed pouches of frozen packaged foods.
[18] A sphere rolls down on two inclined planes of different angles but same height, it does so –
A.
in the same time
B.
with the same speed
C.
in the same time with the same speed
D.
in the same time with the same kinetic energy
Ans:
with the same speed
Explanation :
The velocity of the sphere at the bottom depends only on height and acceleration due to gravity. Both these values are constants. Therefore, the velocity at the bottom remains the same whichever inclined plane the sphere is rolled. However, the sphere will take longer time to reach the bottom of the inclined plane having the smaller inclination. The kinetic energy will be the same. What will differ is time taken to reach the bottom.
[19] During hot weather, the fan produces a feeling of comfort. This is because –
A.
fan supplies cool air
B.
fan cools the air
C.
our perspiration evaporates rapidly
D.
conductivity of air increases
Ans:
our perspiration evaporates rapidly
Explanation :
Fans make the air more comfortable for two reasons: (1) by moving the air, they blow away body heat and evaporate sweat, cooling the body, and (2) they also mix the cooler air near the floor with the warmer air by people's faces.
[20] Stars appears to move from east to west because -
A.
all stars move from east to west
B.
the earth rotates from west to east
C.
the earth rotates from east to west
D.
the background of the stars moves from west to east
Ans:
the earth rotates from west to east
Explanation :
Earth's spin (or rotation) on its axis. Earth rotates or spins toward the east, and that's why the Sun, Moon, planets, and stars all rise in the east and make their way westward across the sky.
[21] An egg sinks in soft water but floats in a concentrated solution of salt because –
A.
Egg absorbs salt from the solution and expands
B.
Albumin dissolves in salt solution and egg becomes lighter
C.
The density of salt solution exceeds the density of eggs
D.
Water has high surface tension
Ans:
The density of salt solution exceeds the density of eggs
Explanation :
Following the density principle, the density of the egg compared to the density of the tap water is lesser (the density principle states that an object or substance with lesser density will float on the surface of the substance or object which has the greater density). Now, with salt, salt makes the density of the tap water to increase and increases also the salinity of the water making the egg float because the density of the water with salt is now greater than the density of the egg and that is why an egg sinks in soft water but floats in a concentrated solution of salt.
[22] A hydrogen balloon floats because of –
A.
Air pressure decreases with decrease in height
B.
Air pressure decreases with decrease in weight
C.
Weight of the balloon is less than the weight of air displaced by it
D.
The pressure inside the balloon is more than the pressure outside it
Ans:
Weight of the balloon is less than the weight of air displaced by it
Explanation :
A hydrogen atom is very light. Most of the air on earth is made up of nitrogen, oxygen, and carbon dioxide. All of these elements are heavier than hydrogen, so the balloon is pushed upwards. Hydrogen weighs 0.08988 grams per liter. Nitrogen, which makes up 80% of the air we breathe, weighs 1.2506 grams per liter.
[23] The term ‘equinox’ means –
A.
The path which the Earth takes around the Sun
B.
The axis of the Earth around which it rotates
C.
When the day and night are of equal duration
D.
The time when the Sun seems to be going round and round in the sky in the Arctic but does not go below the horizon
Ans:
When the day and night are of equal duration
Explanation :
The name "equinox" is derived from the Latin aequus (equal) and nox (night), because around the equinox, the night and day have approximately equal length. An equinox occurs twice a year (around 20 March and 22 September), when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator. The term equinox can also be used in a broader sense, meaning the date when such a passage happens.
[24] After long periods of use, a grey spot develops on the inside of a bulb. This is because –
A.
the tungsten filament evaporates and collects there
B.
the heat of the bulb scorches the glass at the top
C.
dust inside the bulb condenses on the top
D.
glass undergoes a change due to the heat
Ans:
dust inside the bulb condenses on the top
Explanation :
At high operating temperatures, tungsten evaporates from the filament and gradually forms a gray film on the inside of the bulb. The inert gas atoms collide with the evaporating tungsten, causing some of the tungsten atoms to return to the filament. Eventually, however, a thin spot develops in the filament. When this happens, the filament will break and the bulb fails.
[25] The blue colour of water in the sea is due to –
A.
absorption of other colours except blue by water molecules
B.
scattering of blue light by water molecules
C.
reflection of blue light by impurities in sea water
D.
reflection of blue sky by sea water
Ans:
absorption of other colours except blue by water molecules
Explanation :
Almost all sunlight that enters the ocean is absorbed, except very close to the coast. The red, yellow, and green wavelengths of sunlight are absorbed by water molecules in the ocean. The reason the ocean is blue is due to the absorption and scattering of light. The blue wavelengths of light are scattered, similar to the
Explanation :
Condensation is the change of the physical state of matter from gas phase into liquid phase. It is also defined as the change in the state of water vapour to liquid water when in contact with a liquid or solid surface.
[6] If a band is played on the moon the sound will -
A.
reverberate
B.
be heard by us faintly
C.
be heard upto 10km from it
D.
not be heard at any distance at all from it
Ans:
not be heard at any distance at all from it
Explanation :
As there is no atmosphere surrounding the moon, the sound from any band that is played there cannot travel outwards there is no material medium surrounding it for its propagation.
[7] In a water lifting electric pump, We convert –
A.
Electrical energy into Potential energy
B.
Kinetic energy into Electrical energy
C.
Kinetic energy into Potential energy
D.
Electrical energy into Kinetic energy
Ans:
Electrical energy into Potential energy
Explanation :
In a water lifting electric pump, we convert electrical energy into potential energy. In hydraulic pump mechanical energy in converted into potential energy
[8] An electron microscope gives higher magnification than an optical microscope, because:
A.
It uses more powerful lenses
B.
the velocity of electron is smaller than that of visible
C.
the electrons have more energy than the light particles
D.
the wavelength of electrons is smaller as compared to the wavelength of visible light
Ans:
the wavelength of electrons is smaller as compared to the wavelength of visible light
Explanation :
An electron microscope uses a beam of electrons to illuminate a specimen and produce a magnified image. An electron microscope (EM) has greater resolving power than a light-powered optical microscope because electrons have wavelengths about 100,000 times shorter than visible light photons. Magnification is the process of enlarging something only in appearance, not in physical size.
[9] We always see the same lace of the moon, because –
A.
It is smaller than the earth
B.
It revolves on its axis in a direction opposite to that of the earth
C.
It takes equal time for revolution around the earth and rotation on its own axis
D.
It rotates at the same speed as the earth around the sun
Ans:
It takes equal time for revolution around the earth and rotation on its own axis
Explanation :
It is tidal locking that causes the synchronous rotation which causes the Moon to present "just one side" to the Earth all the time. The Moon rotates (spins) but very slowly, making one turn on its axis in the same time it takes to revolve (orbit) around the Earth. So it maintains a "constant face" in our direction.
[10] Which of the following laws validates the statement that matter can neither be created nor destroyed?
A.
Law of conservation of energy
B.
Le Chatelier's Principle
C.
Law of conservation of mass
D.
Law of osmosis
Ans:
Law of conservation of mass
Explanation :
The law of conservation of mass, also known as the principle of mass/matter conservation, states that the mass of an isolated system (closed to all transfers of matter and energy) will remain constant over time. This principle is equivalent to the conservation of energy: when energy or mass is enclosed in a system and none is allowed in or out, its quantity cannot otherwise change over time (hence, its quantity is "conserved" over time).
[11] What is viewed through an electron microscope?
A.
Electrons and other elementary particles
B.
Structure of bacteria and viruses
C.
Inside of human stomach
D.
Inside of the human eye
Ans:
Structure of bacteria and viruses
Explanation :
Electron microscopes are used to observe a wide range of biological and inorganic specimens including microorganisms, cells, large molecules, biopsy samples, metals, and crystals. An electron microscope uses a beam of electrons to illuminate a specimen and produce a magnified image. An electron microscope (EM) has greater resolving power than a light-powered optical microscope because electrons have wavelengths about 100,000 times shorter than visible light photons.
[12] Rain drops fall from great height. Which among the following statements is true regarding it?
A.
they fall with that ultimate velocity, which are different for different droplets
B.
they fall with same ultimate velocity
C.
their velocity increases and they fall with different velocity on the earth
D.
their velocity increases and they fall with same velocity on the earth
Ans:
they fall with that ultimate velocity, which are different for different droplets
Explanation :
Any mass is attracted to the Earth by the pull of gravity. Gravity accelerates all objects towards the ground at a specific rate. Without any other forces present, the speed of an object in free fall will increase the farther or longer it falls. In general the air resistance on an object depends upon several variables. First, it depends upon the shape of the object. Its shape determines the object's drag coefficient: the more aerodynamic the shape, the less drag. Second, it depends upon the size of the object; specifically the cross-sectional area presented to the airflow (perpendicular to the direction of travel).
[13] Which of the following occurred first?
A.
Albert Einstein propounded the General Theory of Relativity
B.
Max Planck unveiled the Quantum Theory
C.
Guglielmo Marconi sent out the first wireless signals
D.
Wright Brothers successfully flew an aircraft
Ans:
Guglielmo Marconi sent out the first wireless signals
Explanation :
Guglielmo Marconi sent out the first wireless signals. In the early summer of 1895 and despite an intervening hill, Marconi achieved signal transmission and reception over a distance of about 2km. Success was indicated initially by the waving of a handkerchief and progressed to the need to fire a gun. The theory of relativity transformed theoretical physics and astronomy during the 20th century.
[14] Why does bleeding occur through the nose in high mountainous regions?
A.
The pressure of blood in capillaries is greater than the outside pressure
B.
The pressure at high altitudes is greater than that on the plains
C.
The blood pressure of a person increases at high altitudes
D.
The blood pressure fluctuates and finally decreases drastically
Ans:
The blood pressure of a person increases at high altitudes
Explanation :
Nose bleeds can occur at high altitudes. The bleeding may be caused by the change in air pressure associated with the change in altitude or the cold dry air common at high altitudes. No matter the cause, the symptoms and treatment of a high altitude bloody nose are the same. A nose bleed is defined as the discharge of blood from the nostrils. Stress and anxiety raises the blood pressure, complicating the nose bleed.
[15] Pipelines in cold countries often burst in winter, because –
A.
Water freezes and expands in its volume
B.
Temperature of ice is less than that of water
C.
Pipelines contract in their volume
D.
Pipelines expand due to freezing
Ans:
Water freezes and expands in its volume
Explanation :
Water expands on freezing. When liquid water is cooled, it contracts like one would expect until a temperature of approximately 4 degrees Celsius is reached. After that, it expands slightly until it reaches the freezing point, and then when it freezes it expands by approximately 9%. The fact that water expands upon freezing causes icebergs to float.
[16] The modulus of rigidity is the ratio of –
A.
Longitudinal stress to longitudinal strain
B.
Volume stress to volume strain
C.
Shearing stress to shearing strain
D.
Tensile stress to tensile strain
Ans:
Shearing stress to shearing strain
Explanation :
In materials science, shear modulus or modulus of rigidity, denoted by G, or sometimes S, is defined as the ratio of shear stress to the shear strain. The shear modulus describes the material's response to shearing strains (like cutting it with dull scissors). The shear modulus is concerned with the deformation of a solid when it experiences a force parallel to one of its surfaces while its opposite face experiences an opposing force (such as friction). In the case of an object that's shaped like a rectangular prism, it will deform into a parallelepiped.
[17] In heating frozen foods in sealed pouches in microwaves, why do you first poke holes in the pouch?
A.
To prevent the steam pressure from bursting open the pouch
B.
To allow the heat to get into the food through the hole
C.
To allow the microwaves to get into the food through the holes
D.
To allow the aroma of the food to come out through the holes
Ans:
To prevent the steam pressure from bursting open the pouch
Explanation :
Anything in a tight skin or shell can explode in a microwave because the water inside can expand and burst through. It is for this very reason that before microwaving, the skin of potatoes should be pricked, winter squash and similar vegetables should be cut in half, eggs should be taken out of shells and holes should be poked in the plastic wrap or sealed pouches of frozen packaged foods.
[18] A sphere rolls down on two inclined planes of different angles but same height, it does so –
A.
in the same time
B.
with the same speed
C.
in the same time with the same speed
D.
in the same time with the same kinetic energy
Ans:
with the same speed
Explanation :
The velocity of the sphere at the bottom depends only on height and acceleration due to gravity. Both these values are constants. Therefore, the velocity at the bottom remains the same whichever inclined plane the sphere is rolled. However, the sphere will take longer time to reach the bottom of the inclined plane having the smaller inclination. The kinetic energy will be the same. What will differ is time taken to reach the bottom.
[19] During hot weather, the fan produces a feeling of comfort. This is because –
A.
fan supplies cool air
B.
fan cools the air
C.
our perspiration evaporates rapidly
D.
conductivity of air increases
Ans:
our perspiration evaporates rapidly
Explanation :
Fans make the air more comfortable for two reasons: (1) by moving the air, they blow away body heat and evaporate sweat, cooling the body, and (2) they also mix the cooler air near the floor with the warmer air by people's faces.
[20] Stars appears to move from east to west because -
A.
all stars move from east to west
B.
the earth rotates from west to east
C.
the earth rotates from east to west
D.
the background of the stars moves from west to east
Ans:
the earth rotates from west to east
Explanation :
Earth's spin (or rotation) on its axis. Earth rotates or spins toward the east, and that's why the Sun, Moon, planets, and stars all rise in the east and make their way westward across the sky.
[21] An egg sinks in soft water but floats in a concentrated solution of salt because –
A.
Egg absorbs salt from the solution and expands
B.
Albumin dissolves in salt solution and egg becomes lighter
C.
The density of salt solution exceeds the density of eggs
D.
Water has high surface tension
Ans:
The density of salt solution exceeds the density of eggs
Explanation :
Following the density principle, the density of the egg compared to the density of the tap water is lesser (the density principle states that an object or substance with lesser density will float on the surface of the substance or object which has the greater density). Now, with salt, salt makes the density of the tap water to increase and increases also the salinity of the water making the egg float because the density of the water with salt is now greater than the density of the egg and that is why an egg sinks in soft water but floats in a concentrated solution of salt.
[22] A hydrogen balloon floats because of –
A.
Air pressure decreases with decrease in height
B.
Air pressure decreases with decrease in weight
C.
Weight of the balloon is less than the weight of air displaced by it
D.
The pressure inside the balloon is more than the pressure outside it
Ans:
Weight of the balloon is less than the weight of air displaced by it
Explanation :
A hydrogen atom is very light. Most of the air on earth is made up of nitrogen, oxygen, and carbon dioxide. All of these elements are heavier than hydrogen, so the balloon is pushed upwards. Hydrogen weighs 0.08988 grams per liter. Nitrogen, which makes up 80% of the air we breathe, weighs 1.2506 grams per liter.
[23] The term ‘equinox’ means –
A.
The path which the Earth takes around the Sun
B.
The axis of the Earth around which it rotates
C.
When the day and night are of equal duration
D.
The time when the Sun seems to be going round and round in the sky in the Arctic but does not go below the horizon
Ans:
When the day and night are of equal duration
Explanation :
The name "equinox" is derived from the Latin aequus (equal) and nox (night), because around the equinox, the night and day have approximately equal length. An equinox occurs twice a year (around 20 March and 22 September), when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator. The term equinox can also be used in a broader sense, meaning the date when such a passage happens.
[24] After long periods of use, a grey spot develops on the inside of a bulb. This is because –
A.
the tungsten filament evaporates and collects there
B.
the heat of the bulb scorches the glass at the top
C.
dust inside the bulb condenses on the top
D.
glass undergoes a change due to the heat
Ans:
dust inside the bulb condenses on the top
Explanation :
At high operating temperatures, tungsten evaporates from the filament and gradually forms a gray film on the inside of the bulb. The inert gas atoms collide with the evaporating tungsten, causing some of the tungsten atoms to return to the filament. Eventually, however, a thin spot develops in the filament. When this happens, the filament will break and the bulb fails.
[25] The blue colour of water in the sea is due to –
A.
absorption of other colours except blue by water molecules
B.
scattering of blue light by water molecules
C.
reflection of blue light by impurities in sea water
D.
reflection of blue sky by sea water
Ans:
absorption of other colours except blue by water molecules
Explanation :
Almost all sunlight that enters the ocean is absorbed, except very close to the coast. The red, yellow, and green wavelengths of sunlight are absorbed by water molecules in the ocean. The reason the ocean is blue is due to the absorption and scattering of light. The blue wavelengths of light are scattered, similar to the
Explanation :
In a water lifting electric pump, we convert electrical energy into potential energy. In hydraulic pump mechanical energy in converted into potential energy
[8] An electron microscope gives higher magnification than an optical microscope, because:
A.
It uses more powerful lenses
B.
the velocity of electron is smaller than that of visible
C.
the electrons have more energy than the light particles
D.
the wavelength of electrons is smaller as compared to the wavelength of visible light
Ans:
the wavelength of electrons is smaller as compared to the wavelength of visible light
Explanation :
An electron microscope uses a beam of electrons to illuminate a specimen and produce a magnified image. An electron microscope (EM) has greater resolving power than a light-powered optical microscope because electrons have wavelengths about 100,000 times shorter than visible light photons. Magnification is the process of enlarging something only in appearance, not in physical size.
[9] We always see the same lace of the moon, because –
A.
It is smaller than the earth
B.
It revolves on its axis in a direction opposite to that of the earth
C.
It takes equal time for revolution around the earth and rotation on its own axis
D.
It rotates at the same speed as the earth around the sun
Ans:
It takes equal time for revolution around the earth and rotation on its own axis
Explanation :
It is tidal locking that causes the synchronous rotation which causes the Moon to present "just one side" to the Earth all the time. The Moon rotates (spins) but very slowly, making one turn on its axis in the same time it takes to revolve (orbit) around the Earth. So it maintains a "constant face" in our direction.
[10] Which of the following laws validates the statement that matter can neither be created nor destroyed?
A.
Law of conservation of energy
B.
Le Chatelier's Principle
C.
Law of conservation of mass
D.
Law of osmosis
Ans:
Law of conservation of mass
Explanation :
The law of conservation of mass, also known as the principle of mass/matter conservation, states that the mass of an isolated system (closed to all transfers of matter and energy) will remain constant over time. This principle is equivalent to the conservation of energy: when energy or mass is enclosed in a system and none is allowed in or out, its quantity cannot otherwise change over time (hence, its quantity is "conserved" over time).
[11] What is viewed through an electron microscope?
A.
Electrons and other elementary particles
B.
Structure of bacteria and viruses
C.
Inside of human stomach
D.
Inside of the human eye
Ans:
Structure of bacteria and viruses
Explanation :
Electron microscopes are used to observe a wide range of biological and inorganic specimens including microorganisms, cells, large molecules, biopsy samples, metals, and crystals. An electron microscope uses a beam of electrons to illuminate a specimen and produce a magnified image. An electron microscope (EM) has greater resolving power than a light-powered optical microscope because electrons have wavelengths about 100,000 times shorter than visible light photons.
[12] Rain drops fall from great height. Which among the following statements is true regarding it?
A.
they fall with that ultimate velocity, which are different for different droplets
B.
they fall with same ultimate velocity
C.
their velocity increases and they fall with different velocity on the earth
D.
their velocity increases and they fall with same velocity on the earth
Ans:
they fall with that ultimate velocity, which are different for different droplets
Explanation :
Any mass is attracted to the Earth by the pull of gravity. Gravity accelerates all objects towards the ground at a specific rate. Without any other forces present, the speed of an object in free fall will increase the farther or longer it falls. In general the air resistance on an object depends upon several variables. First, it depends upon the shape of the object. Its shape determines the object's drag coefficient: the more aerodynamic the shape, the less drag. Second, it depends upon the size of the object; specifically the cross-sectional area presented to the airflow (perpendicular to the direction of travel).
[13] Which of the following occurred first?
A.
Albert Einstein propounded the General Theory of Relativity
B.
Max Planck unveiled the Quantum Theory
C.
Guglielmo Marconi sent out the first wireless signals
D.
Wright Brothers successfully flew an aircraft
Ans:
Guglielmo Marconi sent out the first wireless signals
Explanation :
Guglielmo Marconi sent out the first wireless signals. In the early summer of 1895 and despite an intervening hill, Marconi achieved signal transmission and reception over a distance of about 2km. Success was indicated initially by the waving of a handkerchief and progressed to the need to fire a gun. The theory of relativity transformed theoretical physics and astronomy during the 20th century.
[14] Why does bleeding occur through the nose in high mountainous regions?
A.
The pressure of blood in capillaries is greater than the outside pressure
B.
The pressure at high altitudes is greater than that on the plains
C.
The blood pressure of a person increases at high altitudes
D.
The blood pressure fluctuates and finally decreases drastically
Ans:
The blood pressure of a person increases at high altitudes
Explanation :
Nose bleeds can occur at high altitudes. The bleeding may be caused by the change in air pressure associated with the change in altitude or the cold dry air common at high altitudes. No matter the cause, the symptoms and treatment of a high altitude bloody nose are the same. A nose bleed is defined as the discharge of blood from the nostrils. Stress and anxiety raises the blood pressure, complicating the nose bleed.
[15] Pipelines in cold countries often burst in winter, because –
A.
Water freezes and expands in its volume
B.
Temperature of ice is less than that of water
C.
Pipelines contract in their volume
D.
Pipelines expand due to freezing
Ans:
Water freezes and expands in its volume
Explanation :
Water expands on freezing. When liquid water is cooled, it contracts like one would expect until a temperature of approximately 4 degrees Celsius is reached. After that, it expands slightly until it reaches the freezing point, and then when it freezes it expands by approximately 9%. The fact that water expands upon freezing causes icebergs to float.
[16] The modulus of rigidity is the ratio of –
A.
Longitudinal stress to longitudinal strain
B.
Volume stress to volume strain
C.
Shearing stress to shearing strain
D.
Tensile stress to tensile strain
Ans:
Shearing stress to shearing strain
Explanation :
In materials science, shear modulus or modulus of rigidity, denoted by G, or sometimes S, is defined as the ratio of shear stress to the shear strain. The shear modulus describes the material's response to shearing strains (like cutting it with dull scissors). The shear modulus is concerned with the deformation of a solid when it experiences a force parallel to one of its surfaces while its opposite face experiences an opposing force (such as friction). In the case of an object that's shaped like a rectangular prism, it will deform into a parallelepiped.
[17] In heating frozen foods in sealed pouches in microwaves, why do you first poke holes in the pouch?
A.
To prevent the steam pressure from bursting open the pouch
B.
To allow the heat to get into the food through the hole
C.
To allow the microwaves to get into the food through the holes
D.
To allow the aroma of the food to come out through the holes
Ans:
To prevent the steam pressure from bursting open the pouch
Explanation :
Anything in a tight skin or shell can explode in a microwave because the water inside can expand and burst through. It is for this very reason that before microwaving, the skin of potatoes should be pricked, winter squash and similar vegetables should be cut in half, eggs should be taken out of shells and holes should be poked in the plastic wrap or sealed pouches of frozen packaged foods.
[18] A sphere rolls down on two inclined planes of different angles but same height, it does so –
A.
in the same time
B.
with the same speed
C.
in the same time with the same speed
D.
in the same time with the same kinetic energy
Ans:
with the same speed
Explanation :
The velocity of the sphere at the bottom depends only on height and acceleration due to gravity. Both these values are constants. Therefore, the velocity at the bottom remains the same whichever inclined plane the sphere is rolled. However, the sphere will take longer time to reach the bottom of the inclined plane having the smaller inclination. The kinetic energy will be the same. What will differ is time taken to reach the bottom.
[19] During hot weather, the fan produces a feeling of comfort. This is because –
A.
fan supplies cool air
B.
fan cools the air
C.
our perspiration evaporates rapidly
D.
conductivity of air increases
Ans:
our perspiration evaporates rapidly
Explanation :
Fans make the air more comfortable for two reasons: (1) by moving the air, they blow away body heat and evaporate sweat, cooling the body, and (2) they also mix the cooler air near the floor with the warmer air by people's faces.
[20] Stars appears to move from east to west because -
A.
all stars move from east to west
B.
the earth rotates from west to east
C.
the earth rotates from east to west
D.
the background of the stars moves from west to east
Ans:
the earth rotates from west to east
Explanation :
Earth's spin (or rotation) on its axis. Earth rotates or spins toward the east, and that's why the Sun, Moon, planets, and stars all rise in the east and make their way westward across the sky.
[21] An egg sinks in soft water but floats in a concentrated solution of salt because –
A.
Egg absorbs salt from the solution and expands
B.
Albumin dissolves in salt solution and egg becomes lighter
C.
The density of salt solution exceeds the density of eggs
D.
Water has high surface tension
Ans:
The density of salt solution exceeds the density of eggs
Explanation :
Following the density principle, the density of the egg compared to the density of the tap water is lesser (the density principle states that an object or substance with lesser density will float on the surface of the substance or object which has the greater density). Now, with salt, salt makes the density of the tap water to increase and increases also the salinity of the water making the egg float because the density of the water with salt is now greater than the density of the egg and that is why an egg sinks in soft water but floats in a concentrated solution of salt.
[22] A hydrogen balloon floats because of –
A.
Air pressure decreases with decrease in height
B.
Air pressure decreases with decrease in weight
C.
Weight of the balloon is less than the weight of air displaced by it
D.
The pressure inside the balloon is more than the pressure outside it
Ans:
Weight of the balloon is less than the weight of air displaced by it
Explanation :
A hydrogen atom is very light. Most of the air on earth is made up of nitrogen, oxygen, and carbon dioxide. All of these elements are heavier than hydrogen, so the balloon is pushed upwards. Hydrogen weighs 0.08988 grams per liter. Nitrogen, which makes up 80% of the air we breathe, weighs 1.2506 grams per liter.
[23] The term ‘equinox’ means –
A.
The path which the Earth takes around the Sun
B.
The axis of the Earth around which it rotates
C.
When the day and night are of equal duration
D.
The time when the Sun seems to be going round and round in the sky in the Arctic but does not go below the horizon
Ans:
When the day and night are of equal duration
Explanation :
The name "equinox" is derived from the Latin aequus (equal) and nox (night), because around the equinox, the night and day have approximately equal length. An equinox occurs twice a year (around 20 March and 22 September), when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator. The term equinox can also be used in a broader sense, meaning the date when such a passage happens.
[24] After long periods of use, a grey spot develops on the inside of a bulb. This is because –
A.
the tungsten filament evaporates and collects there
B.
the heat of the bulb scorches the glass at the top
C.
dust inside the bulb condenses on the top
D.
glass undergoes a change due to the heat
Ans:
dust inside the bulb condenses on the top
Explanation :
At high operating temperatures, tungsten evaporates from the filament and gradually forms a gray film on the inside of the bulb. The inert gas atoms collide with the evaporating tungsten, causing some of the tungsten atoms to return to the filament. Eventually, however, a thin spot develops in the filament. When this happens, the filament will break and the bulb fails.
[25] The blue colour of water in the sea is due to –
A.
absorption of other colours except blue by water molecules
B.
scattering of blue light by water molecules
C.
reflection of blue light by impurities in sea water
D.
reflection of blue sky by sea water
Ans:
absorption of other colours except blue by water molecules
Explanation :
Almost all sunlight that enters the ocean is absorbed, except very close to the coast. The red, yellow, and green wavelengths of sunlight are absorbed by water molecules in the ocean. The reason the ocean is blue is due to the absorption and scattering of light. The blue wavelengths of light are scattered, similar to the
Explanation :
It is tidal locking that causes the synchronous rotation which causes the Moon to present "just one side" to the Earth all the time. The Moon rotates (spins) but very slowly, making one turn on its axis in the same time it takes to revolve (orbit) around the Earth. So it maintains a "constant face" in our direction.
[10] Which of the following laws validates the statement that matter can neither be created nor destroyed?
A.
Law of conservation of energy
B.
Le Chatelier's Principle
C.
Law of conservation of mass
D.
Law of osmosis
Ans:
Law of conservation of mass
Explanation :
The law of conservation of mass, also known as the principle of mass/matter conservation, states that the mass of an isolated system (closed to all transfers of matter and energy) will remain constant over time. This principle is equivalent to the conservation of energy: when energy or mass is enclosed in a system and none is allowed in or out, its quantity cannot otherwise change over time (hence, its quantity is "conserved" over time).
[11] What is viewed through an electron microscope?
A.
Electrons and other elementary particles
B.
Structure of bacteria and viruses
C.
Inside of human stomach
D.
Inside of the human eye
Ans:
Structure of bacteria and viruses
Explanation :
Electron microscopes are used to observe a wide range of biological and inorganic specimens including microorganisms, cells, large molecules, biopsy samples, metals, and crystals. An electron microscope uses a beam of electrons to illuminate a specimen and produce a magnified image. An electron microscope (EM) has greater resolving power than a light-powered optical microscope because electrons have wavelengths about 100,000 times shorter than visible light photons.
[12] Rain drops fall from great height. Which among the following statements is true regarding it?
A.
they fall with that ultimate velocity, which are different for different droplets
B.
they fall with same ultimate velocity
C.
their velocity increases and they fall with different velocity on the earth
D.
their velocity increases and they fall with same velocity on the earth
Ans:
they fall with that ultimate velocity, which are different for different droplets
Explanation :
Any mass is attracted to the Earth by the pull of gravity. Gravity accelerates all objects towards the ground at a specific rate. Without any other forces present, the speed of an object in free fall will increase the farther or longer it falls. In general the air resistance on an object depends upon several variables. First, it depends upon the shape of the object. Its shape determines the object's drag coefficient: the more aerodynamic the shape, the less drag. Second, it depends upon the size of the object; specifically the cross-sectional area presented to the airflow (perpendicular to the direction of travel).
[13] Which of the following occurred first?
A.
Albert Einstein propounded the General Theory of Relativity
B.
Max Planck unveiled the Quantum Theory
C.
Guglielmo Marconi sent out the first wireless signals
D.
Wright Brothers successfully flew an aircraft
Ans:
Guglielmo Marconi sent out the first wireless signals
Explanation :
Guglielmo Marconi sent out the first wireless signals. In the early summer of 1895 and despite an intervening hill, Marconi achieved signal transmission and reception over a distance of about 2km. Success was indicated initially by the waving of a handkerchief and progressed to the need to fire a gun. The theory of relativity transformed theoretical physics and astronomy during the 20th century.
[14] Why does bleeding occur through the nose in high mountainous regions?
A.
The pressure of blood in capillaries is greater than the outside pressure
B.
The pressure at high altitudes is greater than that on the plains
C.
The blood pressure of a person increases at high altitudes
D.
The blood pressure fluctuates and finally decreases drastically
Ans:
The blood pressure of a person increases at high altitudes
Explanation :
Nose bleeds can occur at high altitudes. The bleeding may be caused by the change in air pressure associated with the change in altitude or the cold dry air common at high altitudes. No matter the cause, the symptoms and treatment of a high altitude bloody nose are the same. A nose bleed is defined as the discharge of blood from the nostrils. Stress and anxiety raises the blood pressure, complicating the nose bleed.
[15] Pipelines in cold countries often burst in winter, because –
A.
Water freezes and expands in its volume
B.
Temperature of ice is less than that of water
C.
Pipelines contract in their volume
D.
Pipelines expand due to freezing
Ans:
Water freezes and expands in its volume
Explanation :
Water expands on freezing. When liquid water is cooled, it contracts like one would expect until a temperature of approximately 4 degrees Celsius is reached. After that, it expands slightly until it reaches the freezing point, and then when it freezes it expands by approximately 9%. The fact that water expands upon freezing causes icebergs to float.
[16] The modulus of rigidity is the ratio of –
A.
Longitudinal stress to longitudinal strain
B.
Volume stress to volume strain
C.
Shearing stress to shearing strain
D.
Tensile stress to tensile strain
Ans:
Shearing stress to shearing strain
Explanation :
In materials science, shear modulus or modulus of rigidity, denoted by G, or sometimes S, is defined as the ratio of shear stress to the shear strain. The shear modulus describes the material's response to shearing strains (like cutting it with dull scissors). The shear modulus is concerned with the deformation of a solid when it experiences a force parallel to one of its surfaces while its opposite face experiences an opposing force (such as friction). In the case of an object that's shaped like a rectangular prism, it will deform into a parallelepiped.
[17] In heating frozen foods in sealed pouches in microwaves, why do you first poke holes in the pouch?
A.
To prevent the steam pressure from bursting open the pouch
B.
To allow the heat to get into the food through the hole
C.
To allow the microwaves to get into the food through the holes
D.
To allow the aroma of the food to come out through the holes
Ans:
To prevent the steam pressure from bursting open the pouch
Explanation :
Anything in a tight skin or shell can explode in a microwave because the water inside can expand and burst through. It is for this very reason that before microwaving, the skin of potatoes should be pricked, winter squash and similar vegetables should be cut in half, eggs should be taken out of shells and holes should be poked in the plastic wrap or sealed pouches of frozen packaged foods.
[18] A sphere rolls down on two inclined planes of different angles but same height, it does so –
A.
in the same time
B.
with the same speed
C.
in the same time with the same speed
D.
in the same time with the same kinetic energy
Ans:
with the same speed
Explanation :
The velocity of the sphere at the bottom depends only on height and acceleration due to gravity. Both these values are constants. Therefore, the velocity at the bottom remains the same whichever inclined plane the sphere is rolled. However, the sphere will take longer time to reach the bottom of the inclined plane having the smaller inclination. The kinetic energy will be the same. What will differ is time taken to reach the bottom.
[19] During hot weather, the fan produces a feeling of comfort. This is because –
A.
fan supplies cool air
B.
fan cools the air
C.
our perspiration evaporates rapidly
D.
conductivity of air increases
Ans:
our perspiration evaporates rapidly
Explanation :
Fans make the air more comfortable for two reasons: (1) by moving the air, they blow away body heat and evaporate sweat, cooling the body, and (2) they also mix the cooler air near the floor with the warmer air by people's faces.
[20] Stars appears to move from east to west because -
A.
all stars move from east to west
B.
the earth rotates from west to east
C.
the earth rotates from east to west
D.
the background of the stars moves from west to east
Ans:
the earth rotates from west to east
Explanation :
Earth's spin (or rotation) on its axis. Earth rotates or spins toward the east, and that's why the Sun, Moon, planets, and stars all rise in the east and make their way westward across the sky.
[21] An egg sinks in soft water but floats in a concentrated solution of salt because –
A.
Egg absorbs salt from the solution and expands
B.
Albumin dissolves in salt solution and egg becomes lighter
C.
The density of salt solution exceeds the density of eggs
D.
Water has high surface tension
Ans:
The density of salt solution exceeds the density of eggs
Explanation :
Following the density principle, the density of the egg compared to the density of the tap water is lesser (the density principle states that an object or substance with lesser density will float on the surface of the substance or object which has the greater density). Now, with salt, salt makes the density of the tap water to increase and increases also the salinity of the water making the egg float because the density of the water with salt is now greater than the density of the egg and that is why an egg sinks in soft water but floats in a concentrated solution of salt.
[22] A hydrogen balloon floats because of –
A.
Air pressure decreases with decrease in height
B.
Air pressure decreases with decrease in weight
C.
Weight of the balloon is less than the weight of air displaced by it
D.
The pressure inside the balloon is more than the pressure outside it
Ans:
Weight of the balloon is less than the weight of air displaced by it
Explanation :
A hydrogen atom is very light. Most of the air on earth is made up of nitrogen, oxygen, and carbon dioxide. All of these elements are heavier than hydrogen, so the balloon is pushed upwards. Hydrogen weighs 0.08988 grams per liter. Nitrogen, which makes up 80% of the air we breathe, weighs 1.2506 grams per liter.
[23] The term ‘equinox’ means –
A.
The path which the Earth takes around the Sun
B.
The axis of the Earth around which it rotates
C.
When the day and night are of equal duration
D.
The time when the Sun seems to be going round and round in the sky in the Arctic but does not go below the horizon
Ans:
When the day and night are of equal duration
Explanation :
The name "equinox" is derived from the Latin aequus (equal) and nox (night), because around the equinox, the night and day have approximately equal length. An equinox occurs twice a year (around 20 March and 22 September), when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator. The term equinox can also be used in a broader sense, meaning the date when such a passage happens.
[24] After long periods of use, a grey spot develops on the inside of a bulb. This is because –
A.
the tungsten filament evaporates and collects there
B.
the heat of the bulb scorches the glass at the top
C.
dust inside the bulb condenses on the top
D.
glass undergoes a change due to the heat
Ans:
dust inside the bulb condenses on the top
Explanation :
At high operating temperatures, tungsten evaporates from the filament and gradually forms a gray film on the inside of the bulb. The inert gas atoms collide with the evaporating tungsten, causing some of the tungsten atoms to return to the filament. Eventually, however, a thin spot develops in the filament. When this happens, the filament will break and the bulb fails.
[25] The blue colour of water in the sea is due to –
A.
absorption of other colours except blue by water molecules
B.
scattering of blue light by water molecules
C.
reflection of blue light by impurities in sea water
D.
reflection of blue sky by sea water
Ans:
absorption of other colours except blue by water molecules
Explanation :
Almost all sunlight that enters the ocean is absorbed, except very close to the coast. The red, yellow, and green wavelengths of sunlight are absorbed by water molecules in the ocean. The reason the ocean is blue is due to the absorption and scattering of light. The blue wavelengths of light are scattered, similar to the
Explanation :
Electron microscopes are used to observe a wide range of biological and inorganic specimens including microorganisms, cells, large molecules, biopsy samples, metals, and crystals. An electron microscope uses a beam of electrons to illuminate a specimen and produce a magnified image. An electron microscope (EM) has greater resolving power than a light-powered optical microscope because electrons have wavelengths about 100,000 times shorter than visible light photons.
[12] Rain drops fall from great height. Which among the following statements is true regarding it?
A.
they fall with that ultimate velocity, which are different for different droplets
B.
they fall with same ultimate velocity
C.
their velocity increases and they fall with different velocity on the earth
D.
their velocity increases and they fall with same velocity on the earth
Ans:
they fall with that ultimate velocity, which are different for different droplets
Explanation :
Any mass is attracted to the Earth by the pull of gravity. Gravity accelerates all objects towards the ground at a specific rate. Without any other forces present, the speed of an object in free fall will increase the farther or longer it falls. In general the air resistance on an object depends upon several variables. First, it depends upon the shape of the object. Its shape determines the object's drag coefficient: the more aerodynamic the shape, the less drag. Second, it depends upon the size of the object; specifically the cross-sectional area presented to the airflow (perpendicular to the direction of travel).
[13] Which of the following occurred first?
A.
Albert Einstein propounded the General Theory of Relativity
B.
Max Planck unveiled the Quantum Theory
C.
Guglielmo Marconi sent out the first wireless signals
D.
Wright Brothers successfully flew an aircraft
Ans:
Guglielmo Marconi sent out the first wireless signals
Explanation :
Guglielmo Marconi sent out the first wireless signals. In the early summer of 1895 and despite an intervening hill, Marconi achieved signal transmission and reception over a distance of about 2km. Success was indicated initially by the waving of a handkerchief and progressed to the need to fire a gun. The theory of relativity transformed theoretical physics and astronomy during the 20th century.
[14] Why does bleeding occur through the nose in high mountainous regions?
A.
The pressure of blood in capillaries is greater than the outside pressure
B.
The pressure at high altitudes is greater than that on the plains
C.
The blood pressure of a person increases at high altitudes
D.
The blood pressure fluctuates and finally decreases drastically
Ans:
The blood pressure of a person increases at high altitudes
Explanation :
Nose bleeds can occur at high altitudes. The bleeding may be caused by the change in air pressure associated with the change in altitude or the cold dry air common at high altitudes. No matter the cause, the symptoms and treatment of a high altitude bloody nose are the same. A nose bleed is defined as the discharge of blood from the nostrils. Stress and anxiety raises the blood pressure, complicating the nose bleed.
[15] Pipelines in cold countries often burst in winter, because –
A.
Water freezes and expands in its volume
B.
Temperature of ice is less than that of water
C.
Pipelines contract in their volume
D.
Pipelines expand due to freezing
Ans:
Water freezes and expands in its volume
Explanation :
Water expands on freezing. When liquid water is cooled, it contracts like one would expect until a temperature of approximately 4 degrees Celsius is reached. After that, it expands slightly until it reaches the freezing point, and then when it freezes it expands by approximately 9%. The fact that water expands upon freezing causes icebergs to float.
[16] The modulus of rigidity is the ratio of –
A.
Longitudinal stress to longitudinal strain
B.
Volume stress to volume strain
C.
Shearing stress to shearing strain
D.
Tensile stress to tensile strain
Ans:
Shearing stress to shearing strain
Explanation :
In materials science, shear modulus or modulus of rigidity, denoted by G, or sometimes S, is defined as the ratio of shear stress to the shear strain. The shear modulus describes the material's response to shearing strains (like cutting it with dull scissors). The shear modulus is concerned with the deformation of a solid when it experiences a force parallel to one of its surfaces while its opposite face experiences an opposing force (such as friction). In the case of an object that's shaped like a rectangular prism, it will deform into a parallelepiped.
[17] In heating frozen foods in sealed pouches in microwaves, why do you first poke holes in the pouch?
A.
To prevent the steam pressure from bursting open the pouch
B.
To allow the heat to get into the food through the hole
C.
To allow the microwaves to get into the food through the holes
D.
To allow the aroma of the food to come out through the holes
Ans:
To prevent the steam pressure from bursting open the pouch
Explanation :
Anything in a tight skin or shell can explode in a microwave because the water inside can expand and burst through. It is for this very reason that before microwaving, the skin of potatoes should be pricked, winter squash and similar vegetables should be cut in half, eggs should be taken out of shells and holes should be poked in the plastic wrap or sealed pouches of frozen packaged foods.
[18] A sphere rolls down on two inclined planes of different angles but same height, it does so –
A.
in the same time
B.
with the same speed
C.
in the same time with the same speed
D.
in the same time with the same kinetic energy
Ans:
with the same speed
Explanation :
The velocity of the sphere at the bottom depends only on height and acceleration due to gravity. Both these values are constants. Therefore, the velocity at the bottom remains the same whichever inclined plane the sphere is rolled. However, the sphere will take longer time to reach the bottom of the inclined plane having the smaller inclination. The kinetic energy will be the same. What will differ is time taken to reach the bottom.
[19] During hot weather, the fan produces a feeling of comfort. This is because –
A.
fan supplies cool air
B.
fan cools the air
C.
our perspiration evaporates rapidly
D.
conductivity of air increases
Ans:
our perspiration evaporates rapidly
Explanation :
Fans make the air more comfortable for two reasons: (1) by moving the air, they blow away body heat and evaporate sweat, cooling the body, and (2) they also mix the cooler air near the floor with the warmer air by people's faces.
[20] Stars appears to move from east to west because -
A.
all stars move from east to west
B.
the earth rotates from west to east
C.
the earth rotates from east to west
D.
the background of the stars moves from west to east
Ans:
the earth rotates from west to east
Explanation :
Earth's spin (or rotation) on its axis. Earth rotates or spins toward the east, and that's why the Sun, Moon, planets, and stars all rise in the east and make their way westward across the sky.
[21] An egg sinks in soft water but floats in a concentrated solution of salt because –
A.
Egg absorbs salt from the solution and expands
B.
Albumin dissolves in salt solution and egg becomes lighter
C.
The density of salt solution exceeds the density of eggs
D.
Water has high surface tension
Ans:
The density of salt solution exceeds the density of eggs
Explanation :
Following the density principle, the density of the egg compared to the density of the tap water is lesser (the density principle states that an object or substance with lesser density will float on the surface of the substance or object which has the greater density). Now, with salt, salt makes the density of the tap water to increase and increases also the salinity of the water making the egg float because the density of the water with salt is now greater than the density of the egg and that is why an egg sinks in soft water but floats in a concentrated solution of salt.
[22] A hydrogen balloon floats because of –
A.
Air pressure decreases with decrease in height
B.
Air pressure decreases with decrease in weight
C.
Weight of the balloon is less than the weight of air displaced by it
D.
The pressure inside the balloon is more than the pressure outside it
Ans:
Weight of the balloon is less than the weight of air displaced by it
Explanation :
A hydrogen atom is very light. Most of the air on earth is made up of nitrogen, oxygen, and carbon dioxide. All of these elements are heavier than hydrogen, so the balloon is pushed upwards. Hydrogen weighs 0.08988 grams per liter. Nitrogen, which makes up 80% of the air we breathe, weighs 1.2506 grams per liter.
[23] The term ‘equinox’ means –
A.
The path which the Earth takes around the Sun
B.
The axis of the Earth around which it rotates
C.
When the day and night are of equal duration
D.
The time when the Sun seems to be going round and round in the sky in the Arctic but does not go below the horizon
Ans:
When the day and night are of equal duration
Explanation :
The name "equinox" is derived from the Latin aequus (equal) and nox (night), because around the equinox, the night and day have approximately equal length. An equinox occurs twice a year (around 20 March and 22 September), when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator. The term equinox can also be used in a broader sense, meaning the date when such a passage happens.
[24] After long periods of use, a grey spot develops on the inside of a bulb. This is because –
A.
the tungsten filament evaporates and collects there
B.
the heat of the bulb scorches the glass at the top
C.
dust inside the bulb condenses on the top
D.
glass undergoes a change due to the heat
Ans:
dust inside the bulb condenses on the top
Explanation :
At high operating temperatures, tungsten evaporates from the filament and gradually forms a gray film on the inside of the bulb. The inert gas atoms collide with the evaporating tungsten, causing some of the tungsten atoms to return to the filament. Eventually, however, a thin spot develops in the filament. When this happens, the filament will break and the bulb fails.
[25] The blue colour of water in the sea is due to –
A.
absorption of other colours except blue by water molecules
B.
scattering of blue light by water molecules
C.
reflection of blue light by impurities in sea water
D.
reflection of blue sky by sea water
Ans:
absorption of other colours except blue by water molecules
Explanation :
Almost all sunlight that enters the ocean is absorbed, except very close to the coast. The red, yellow, and green wavelengths of sunlight are absorbed by water molecules in the ocean. The reason the ocean is blue is due to the absorption and scattering of light. The blue wavelengths of light are scattered, similar to the
Explanation :
Guglielmo Marconi sent out the first wireless signals. In the early summer of 1895 and despite an intervening hill, Marconi achieved signal transmission and reception over a distance of about 2km. Success was indicated initially by the waving of a handkerchief and progressed to the need to fire a gun. The theory of relativity transformed theoretical physics and astronomy during the 20th century.
[14] Why does bleeding occur through the nose in high mountainous regions?
A.
The pressure of blood in capillaries is greater than the outside pressure
B.
The pressure at high altitudes is greater than that on the plains
C.
The blood pressure of a person increases at high altitudes
D.
The blood pressure fluctuates and finally decreases drastically
Ans:
The blood pressure of a person increases at high altitudes
Explanation :
Nose bleeds can occur at high altitudes. The bleeding may be caused by the change in air pressure associated with the change in altitude or the cold dry air common at high altitudes. No matter the cause, the symptoms and treatment of a high altitude bloody nose are the same. A nose bleed is defined as the discharge of blood from the nostrils. Stress and anxiety raises the blood pressure, complicating the nose bleed.
[15] Pipelines in cold countries often burst in winter, because –
A.
Water freezes and expands in its volume
B.
Temperature of ice is less than that of water
C.
Pipelines contract in their volume
D.
Pipelines expand due to freezing
Ans:
Water freezes and expands in its volume
Explanation :
Water expands on freezing. When liquid water is cooled, it contracts like one would expect until a temperature of approximately 4 degrees Celsius is reached. After that, it expands slightly until it reaches the freezing point, and then when it freezes it expands by approximately 9%. The fact that water expands upon freezing causes icebergs to float.
[16] The modulus of rigidity is the ratio of –
A.
Longitudinal stress to longitudinal strain
B.
Volume stress to volume strain
C.
Shearing stress to shearing strain
D.
Tensile stress to tensile strain
Ans:
Shearing stress to shearing strain
Explanation :
In materials science, shear modulus or modulus of rigidity, denoted by G, or sometimes S, is defined as the ratio of shear stress to the shear strain. The shear modulus describes the material's response to shearing strains (like cutting it with dull scissors). The shear modulus is concerned with the deformation of a solid when it experiences a force parallel to one of its surfaces while its opposite face experiences an opposing force (such as friction). In the case of an object that's shaped like a rectangular prism, it will deform into a parallelepiped.
[17] In heating frozen foods in sealed pouches in microwaves, why do you first poke holes in the pouch?
A.
To prevent the steam pressure from bursting open the pouch
B.
To allow the heat to get into the food through the hole
C.
To allow the microwaves to get into the food through the holes
D.
To allow the aroma of the food to come out through the holes
Ans:
To prevent the steam pressure from bursting open the pouch
Explanation :
Anything in a tight skin or shell can explode in a microwave because the water inside can expand and burst through. It is for this very reason that before microwaving, the skin of potatoes should be pricked, winter squash and similar vegetables should be cut in half, eggs should be taken out of shells and holes should be poked in the plastic wrap or sealed pouches of frozen packaged foods.
[18] A sphere rolls down on two inclined planes of different angles but same height, it does so –
A.
in the same time
B.
with the same speed
C.
in the same time with the same speed
D.
in the same time with the same kinetic energy
Ans:
with the same speed
Explanation :
The velocity of the sphere at the bottom depends only on height and acceleration due to gravity. Both these values are constants. Therefore, the velocity at the bottom remains the same whichever inclined plane the sphere is rolled. However, the sphere will take longer time to reach the bottom of the inclined plane having the smaller inclination. The kinetic energy will be the same. What will differ is time taken to reach the bottom.
[19] During hot weather, the fan produces a feeling of comfort. This is because –
A.
fan supplies cool air
B.
fan cools the air
C.
our perspiration evaporates rapidly
D.
conductivity of air increases
Ans:
our perspiration evaporates rapidly
Explanation :
Fans make the air more comfortable for two reasons: (1) by moving the air, they blow away body heat and evaporate sweat, cooling the body, and (2) they also mix the cooler air near the floor with the warmer air by people's faces.
[20] Stars appears to move from east to west because -
A.
all stars move from east to west
B.
the earth rotates from west to east
C.
the earth rotates from east to west
D.
the background of the stars moves from west to east
Ans:
the earth rotates from west to east
Explanation :
Earth's spin (or rotation) on its axis. Earth rotates or spins toward the east, and that's why the Sun, Moon, planets, and stars all rise in the east and make their way westward across the sky.
[21] An egg sinks in soft water but floats in a concentrated solution of salt because –
A.
Egg absorbs salt from the solution and expands
B.
Albumin dissolves in salt solution and egg becomes lighter
C.
The density of salt solution exceeds the density of eggs
D.
Water has high surface tension
Ans:
The density of salt solution exceeds the density of eggs
Explanation :
Following the density principle, the density of the egg compared to the density of the tap water is lesser (the density principle states that an object or substance with lesser density will float on the surface of the substance or object which has the greater density). Now, with salt, salt makes the density of the tap water to increase and increases also the salinity of the water making the egg float because the density of the water with salt is now greater than the density of the egg and that is why an egg sinks in soft water but floats in a concentrated solution of salt.
[22] A hydrogen balloon floats because of –
A.
Air pressure decreases with decrease in height
B.
Air pressure decreases with decrease in weight
C.
Weight of the balloon is less than the weight of air displaced by it
D.
The pressure inside the balloon is more than the pressure outside it
Ans:
Weight of the balloon is less than the weight of air displaced by it
Explanation :
A hydrogen atom is very light. Most of the air on earth is made up of nitrogen, oxygen, and carbon dioxide. All of these elements are heavier than hydrogen, so the balloon is pushed upwards. Hydrogen weighs 0.08988 grams per liter. Nitrogen, which makes up 80% of the air we breathe, weighs 1.2506 grams per liter.
[23] The term ‘equinox’ means –
A.
The path which the Earth takes around the Sun
B.
The axis of the Earth around which it rotates
C.
When the day and night are of equal duration
D.
The time when the Sun seems to be going round and round in the sky in the Arctic but does not go below the horizon
Ans:
When the day and night are of equal duration
Explanation :
The name "equinox" is derived from the Latin aequus (equal) and nox (night), because around the equinox, the night and day have approximately equal length. An equinox occurs twice a year (around 20 March and 22 September), when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator. The term equinox can also be used in a broader sense, meaning the date when such a passage happens.
[24] After long periods of use, a grey spot develops on the inside of a bulb. This is because –
A.
the tungsten filament evaporates and collects there
B.
the heat of the bulb scorches the glass at the top
C.
dust inside the bulb condenses on the top
D.
glass undergoes a change due to the heat
Ans:
dust inside the bulb condenses on the top
Explanation :
At high operating temperatures, tungsten evaporates from the filament and gradually forms a gray film on the inside of the bulb. The inert gas atoms collide with the evaporating tungsten, causing some of the tungsten atoms to return to the filament. Eventually, however, a thin spot develops in the filament. When this happens, the filament will break and the bulb fails.
[25] The blue colour of water in the sea is due to –
A.
absorption of other colours except blue by water molecules
B.
scattering of blue light by water molecules
C.
reflection of blue light by impurities in sea water
D.
reflection of blue sky by sea water
Ans:
absorption of other colours except blue by water molecules
Explanation :
Almost all sunlight that enters the ocean is absorbed, except very close to the coast. The red, yellow, and green wavelengths of sunlight are absorbed by water molecules in the ocean. The reason the ocean is blue is due to the absorption and scattering of light. The blue wavelengths of light are scattered, similar to the
Explanation :
Water expands on freezing. When liquid water is cooled, it contracts like one would expect until a temperature of approximately 4 degrees Celsius is reached. After that, it expands slightly until it reaches the freezing point, and then when it freezes it expands by approximately 9%. The fact that water expands upon freezing causes icebergs to float.
[16] The modulus of rigidity is the ratio of –
A.
Longitudinal stress to longitudinal strain
B.
Volume stress to volume strain
C.
Shearing stress to shearing strain
D.
Tensile stress to tensile strain
Ans:
Shearing stress to shearing strain
Explanation :
In materials science, shear modulus or modulus of rigidity, denoted by G, or sometimes S, is defined as the ratio of shear stress to the shear strain. The shear modulus describes the material's response to shearing strains (like cutting it with dull scissors). The shear modulus is concerned with the deformation of a solid when it experiences a force parallel to one of its surfaces while its opposite face experiences an opposing force (such as friction). In the case of an object that's shaped like a rectangular prism, it will deform into a parallelepiped.
[17] In heating frozen foods in sealed pouches in microwaves, why do you first poke holes in the pouch?
A.
To prevent the steam pressure from bursting open the pouch
B.
To allow the heat to get into the food through the hole
C.
To allow the microwaves to get into the food through the holes
D.
To allow the aroma of the food to come out through the holes
Ans:
To prevent the steam pressure from bursting open the pouch
Explanation :
Anything in a tight skin or shell can explode in a microwave because the water inside can expand and burst through. It is for this very reason that before microwaving, the skin of potatoes should be pricked, winter squash and similar vegetables should be cut in half, eggs should be taken out of shells and holes should be poked in the plastic wrap or sealed pouches of frozen packaged foods.
[18] A sphere rolls down on two inclined planes of different angles but same height, it does so –
A.
in the same time
B.
with the same speed
C.
in the same time with the same speed
D.
in the same time with the same kinetic energy
Ans:
with the same speed
Explanation :
The velocity of the sphere at the bottom depends only on height and acceleration due to gravity. Both these values are constants. Therefore, the velocity at the bottom remains the same whichever inclined plane the sphere is rolled. However, the sphere will take longer time to reach the bottom of the inclined plane having the smaller inclination. The kinetic energy will be the same. What will differ is time taken to reach the bottom.
[19] During hot weather, the fan produces a feeling of comfort. This is because –
A.
fan supplies cool air
B.
fan cools the air
C.
our perspiration evaporates rapidly
D.
conductivity of air increases
Ans:
our perspiration evaporates rapidly
Explanation :
Fans make the air more comfortable for two reasons: (1) by moving the air, they blow away body heat and evaporate sweat, cooling the body, and (2) they also mix the cooler air near the floor with the warmer air by people's faces.
[20] Stars appears to move from east to west because -
A.
all stars move from east to west
B.
the earth rotates from west to east
C.
the earth rotates from east to west
D.
the background of the stars moves from west to east
Ans:
the earth rotates from west to east
Explanation :
Earth's spin (or rotation) on its axis. Earth rotates or spins toward the east, and that's why the Sun, Moon, planets, and stars all rise in the east and make their way westward across the sky.
[21] An egg sinks in soft water but floats in a concentrated solution of salt because –
A.
Egg absorbs salt from the solution and expands
B.
Albumin dissolves in salt solution and egg becomes lighter
C.
The density of salt solution exceeds the density of eggs
D.
Water has high surface tension
Ans:
The density of salt solution exceeds the density of eggs
Explanation :
Following the density principle, the density of the egg compared to the density of the tap water is lesser (the density principle states that an object or substance with lesser density will float on the surface of the substance or object which has the greater density). Now, with salt, salt makes the density of the tap water to increase and increases also the salinity of the water making the egg float because the density of the water with salt is now greater than the density of the egg and that is why an egg sinks in soft water but floats in a concentrated solution of salt.
[22] A hydrogen balloon floats because of –
A.
Air pressure decreases with decrease in height
B.
Air pressure decreases with decrease in weight
C.
Weight of the balloon is less than the weight of air displaced by it
D.
The pressure inside the balloon is more than the pressure outside it
Ans:
Weight of the balloon is less than the weight of air displaced by it
Explanation :
A hydrogen atom is very light. Most of the air on earth is made up of nitrogen, oxygen, and carbon dioxide. All of these elements are heavier than hydrogen, so the balloon is pushed upwards. Hydrogen weighs 0.08988 grams per liter. Nitrogen, which makes up 80% of the air we breathe, weighs 1.2506 grams per liter.
[23] The term ‘equinox’ means –
A.
The path which the Earth takes around the Sun
B.
The axis of the Earth around which it rotates
C.
When the day and night are of equal duration
D.
The time when the Sun seems to be going round and round in the sky in the Arctic but does not go below the horizon
Ans:
When the day and night are of equal duration
Explanation :
The name "equinox" is derived from the Latin aequus (equal) and nox (night), because around the equinox, the night and day have approximately equal length. An equinox occurs twice a year (around 20 March and 22 September), when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator. The term equinox can also be used in a broader sense, meaning the date when such a passage happens.
[24] After long periods of use, a grey spot develops on the inside of a bulb. This is because –
A.
the tungsten filament evaporates and collects there
B.
the heat of the bulb scorches the glass at the top
C.
dust inside the bulb condenses on the top
D.
glass undergoes a change due to the heat
Ans:
dust inside the bulb condenses on the top
Explanation :
At high operating temperatures, tungsten evaporates from the filament and gradually forms a gray film on the inside of the bulb. The inert gas atoms collide with the evaporating tungsten, causing some of the tungsten atoms to return to the filament. Eventually, however, a thin spot develops in the filament. When this happens, the filament will break and the bulb fails.
[25] The blue colour of water in the sea is due to –
A.
absorption of other colours except blue by water molecules
B.
scattering of blue light by water molecules
C.
reflection of blue light by impurities in sea water
D.
reflection of blue sky by sea water
Ans:
absorption of other colours except blue by water molecules
Explanation :
Almost all sunlight that enters the ocean is absorbed, except very close to the coast. The red, yellow, and green wavelengths of sunlight are absorbed by water molecules in the ocean. The reason the ocean is blue is due to the absorption and scattering of light. The blue wavelengths of light are scattered, similar to the
Explanation :
Anything in a tight skin or shell can explode in a microwave because the water inside can expand and burst through. It is for this very reason that before microwaving, the skin of potatoes should be pricked, winter squash and similar vegetables should be cut in half, eggs should be taken out of shells and holes should be poked in the plastic wrap or sealed pouches of frozen packaged foods.
[18] A sphere rolls down on two inclined planes of different angles but same height, it does so –
A.
in the same time
B.
with the same speed
C.
in the same time with the same speed
D.
in the same time with the same kinetic energy
Ans:
with the same speed
Explanation :
The velocity of the sphere at the bottom depends only on height and acceleration due to gravity. Both these values are constants. Therefore, the velocity at the bottom remains the same whichever inclined plane the sphere is rolled. However, the sphere will take longer time to reach the bottom of the inclined plane having the smaller inclination. The kinetic energy will be the same. What will differ is time taken to reach the bottom.
[19] During hot weather, the fan produces a feeling of comfort. This is because –
A.
fan supplies cool air
B.
fan cools the air
C.
our perspiration evaporates rapidly
D.
conductivity of air increases
Ans:
our perspiration evaporates rapidly
Explanation :
Fans make the air more comfortable for two reasons: (1) by moving the air, they blow away body heat and evaporate sweat, cooling the body, and (2) they also mix the cooler air near the floor with the warmer air by people's faces.
[20] Stars appears to move from east to west because -
A.
all stars move from east to west
B.
the earth rotates from west to east
C.
the earth rotates from east to west
D.
the background of the stars moves from west to east
Ans:
the earth rotates from west to east
Explanation :
Earth's spin (or rotation) on its axis. Earth rotates or spins toward the east, and that's why the Sun, Moon, planets, and stars all rise in the east and make their way westward across the sky.
[21] An egg sinks in soft water but floats in a concentrated solution of salt because –
A.
Egg absorbs salt from the solution and expands
B.
Albumin dissolves in salt solution and egg becomes lighter
C.
The density of salt solution exceeds the density of eggs
D.
Water has high surface tension
Ans:
The density of salt solution exceeds the density of eggs
Explanation :
Following the density principle, the density of the egg compared to the density of the tap water is lesser (the density principle states that an object or substance with lesser density will float on the surface of the substance or object which has the greater density). Now, with salt, salt makes the density of the tap water to increase and increases also the salinity of the water making the egg float because the density of the water with salt is now greater than the density of the egg and that is why an egg sinks in soft water but floats in a concentrated solution of salt.
[22] A hydrogen balloon floats because of –
A.
Air pressure decreases with decrease in height
B.
Air pressure decreases with decrease in weight
C.
Weight of the balloon is less than the weight of air displaced by it
D.
The pressure inside the balloon is more than the pressure outside it
Ans:
Weight of the balloon is less than the weight of air displaced by it
Explanation :
A hydrogen atom is very light. Most of the air on earth is made up of nitrogen, oxygen, and carbon dioxide. All of these elements are heavier than hydrogen, so the balloon is pushed upwards. Hydrogen weighs 0.08988 grams per liter. Nitrogen, which makes up 80% of the air we breathe, weighs 1.2506 grams per liter.
[23] The term ‘equinox’ means –
A.
The path which the Earth takes around the Sun
B.
The axis of the Earth around which it rotates
C.
When the day and night are of equal duration
D.
The time when the Sun seems to be going round and round in the sky in the Arctic but does not go below the horizon
Ans:
When the day and night are of equal duration
Explanation :
The name "equinox" is derived from the Latin aequus (equal) and nox (night), because around the equinox, the night and day have approximately equal length. An equinox occurs twice a year (around 20 March and 22 September), when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator. The term equinox can also be used in a broader sense, meaning the date when such a passage happens.
[24] After long periods of use, a grey spot develops on the inside of a bulb. This is because –
A.
the tungsten filament evaporates and collects there
B.
the heat of the bulb scorches the glass at the top
C.
dust inside the bulb condenses on the top
D.
glass undergoes a change due to the heat
Ans:
dust inside the bulb condenses on the top
Explanation :
At high operating temperatures, tungsten evaporates from the filament and gradually forms a gray film on the inside of the bulb. The inert gas atoms collide with the evaporating tungsten, causing some of the tungsten atoms to return to the filament. Eventually, however, a thin spot develops in the filament. When this happens, the filament will break and the bulb fails.
[25] The blue colour of water in the sea is due to –
A.
absorption of other colours except blue by water molecules
B.
scattering of blue light by water molecules
C.
reflection of blue light by impurities in sea water
D.
reflection of blue sky by sea water
Ans:
absorption of other colours except blue by water molecules
Explanation :
Almost all sunlight that enters the ocean is absorbed, except very close to the coast. The red, yellow, and green wavelengths of sunlight are absorbed by water molecules in the ocean. The reason the ocean is blue is due to the absorption and scattering of light. The blue wavelengths of light are scattered, similar to the
Explanation :
Fans make the air more comfortable for two reasons: (1) by moving the air, they blow away body heat and evaporate sweat, cooling the body, and (2) they also mix the cooler air near the floor with the warmer air by people's faces.
[20] Stars appears to move from east to west because -
A.
all stars move from east to west
B.
the earth rotates from west to east
C.
the earth rotates from east to west
D.
the background of the stars moves from west to east
Ans:
the earth rotates from west to east
Explanation :
Earth's spin (or rotation) on its axis. Earth rotates or spins toward the east, and that's why the Sun, Moon, planets, and stars all rise in the east and make their way westward across the sky.
[21] An egg sinks in soft water but floats in a concentrated solution of salt because –
A.
Egg absorbs salt from the solution and expands
B.
Albumin dissolves in salt solution and egg becomes lighter
C.
The density of salt solution exceeds the density of eggs
D.
Water has high surface tension
Ans:
The density of salt solution exceeds the density of eggs
Explanation :
Following the density principle, the density of the egg compared to the density of the tap water is lesser (the density principle states that an object or substance with lesser density will float on the surface of the substance or object which has the greater density). Now, with salt, salt makes the density of the tap water to increase and increases also the salinity of the water making the egg float because the density of the water with salt is now greater than the density of the egg and that is why an egg sinks in soft water but floats in a concentrated solution of salt.
[22] A hydrogen balloon floats because of –
A.
Air pressure decreases with decrease in height
B.
Air pressure decreases with decrease in weight
C.
Weight of the balloon is less than the weight of air displaced by it
D.
The pressure inside the balloon is more than the pressure outside it
Ans:
Weight of the balloon is less than the weight of air displaced by it
Explanation :
A hydrogen atom is very light. Most of the air on earth is made up of nitrogen, oxygen, and carbon dioxide. All of these elements are heavier than hydrogen, so the balloon is pushed upwards. Hydrogen weighs 0.08988 grams per liter. Nitrogen, which makes up 80% of the air we breathe, weighs 1.2506 grams per liter.
[23] The term ‘equinox’ means –
A.
The path which the Earth takes around the Sun
B.
The axis of the Earth around which it rotates
C.
When the day and night are of equal duration
D.
The time when the Sun seems to be going round and round in the sky in the Arctic but does not go below the horizon
Ans:
When the day and night are of equal duration
Explanation :
The name "equinox" is derived from the Latin aequus (equal) and nox (night), because around the equinox, the night and day have approximately equal length. An equinox occurs twice a year (around 20 March and 22 September), when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator. The term equinox can also be used in a broader sense, meaning the date when such a passage happens.
[24] After long periods of use, a grey spot develops on the inside of a bulb. This is because –
A.
the tungsten filament evaporates and collects there
B.
the heat of the bulb scorches the glass at the top
C.
dust inside the bulb condenses on the top
D.
glass undergoes a change due to the heat
Ans:
dust inside the bulb condenses on the top
Explanation :
At high operating temperatures, tungsten evaporates from the filament and gradually forms a gray film on the inside of the bulb. The inert gas atoms collide with the evaporating tungsten, causing some of the tungsten atoms to return to the filament. Eventually, however, a thin spot develops in the filament. When this happens, the filament will break and the bulb fails.
[25] The blue colour of water in the sea is due to –
A.
absorption of other colours except blue by water molecules
B.
scattering of blue light by water molecules
C.
reflection of blue light by impurities in sea water
D.
reflection of blue sky by sea water
Ans:
absorption of other colours except blue by water molecules
Explanation :
Almost all sunlight that enters the ocean is absorbed, except very close to the coast. The red, yellow, and green wavelengths of sunlight are absorbed by water molecules in the ocean. The reason the ocean is blue is due to the absorption and scattering of light. The blue wavelengths of light are scattered, similar to the
Explanation :
Following the density principle, the density of the egg compared to the density of the tap water is lesser (the density principle states that an object or substance with lesser density will float on the surface of the substance or object which has the greater density). Now, with salt, salt makes the density of the tap water to increase and increases also the salinity of the water making the egg float because the density of the water with salt is now greater than the density of the egg and that is why an egg sinks in soft water but floats in a concentrated solution of salt.
[22] A hydrogen balloon floats because of –
A.
Air pressure decreases with decrease in height
B.
Air pressure decreases with decrease in weight
C.
Weight of the balloon is less than the weight of air displaced by it
D.
The pressure inside the balloon is more than the pressure outside it
Ans:
Weight of the balloon is less than the weight of air displaced by it
Explanation :
A hydrogen atom is very light. Most of the air on earth is made up of nitrogen, oxygen, and carbon dioxide. All of these elements are heavier than hydrogen, so the balloon is pushed upwards. Hydrogen weighs 0.08988 grams per liter. Nitrogen, which makes up 80% of the air we breathe, weighs 1.2506 grams per liter.
[23] The term ‘equinox’ means –
A.
The path which the Earth takes around the Sun
B.
The axis of the Earth around which it rotates
C.
When the day and night are of equal duration
D.
The time when the Sun seems to be going round and round in the sky in the Arctic but does not go below the horizon
Ans:
When the day and night are of equal duration
Explanation :
The name "equinox" is derived from the Latin aequus (equal) and nox (night), because around the equinox, the night and day have approximately equal length. An equinox occurs twice a year (around 20 March and 22 September), when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator. The term equinox can also be used in a broader sense, meaning the date when such a passage happens.
[24] After long periods of use, a grey spot develops on the inside of a bulb. This is because –
A.
the tungsten filament evaporates and collects there
B.
the heat of the bulb scorches the glass at the top
C.
dust inside the bulb condenses on the top
D.
glass undergoes a change due to the heat
Ans:
dust inside the bulb condenses on the top
Explanation :
At high operating temperatures, tungsten evaporates from the filament and gradually forms a gray film on the inside of the bulb. The inert gas atoms collide with the evaporating tungsten, causing some of the tungsten atoms to return to the filament. Eventually, however, a thin spot develops in the filament. When this happens, the filament will break and the bulb fails.
[25] The blue colour of water in the sea is due to –
A.
absorption of other colours except blue by water molecules
B.
scattering of blue light by water molecules
C.
reflection of blue light by impurities in sea water
D.
reflection of blue sky by sea water
Ans:
absorption of other colours except blue by water molecules
Explanation :
Almost all sunlight that enters the ocean is absorbed, except very close to the coast. The red, yellow, and green wavelengths of sunlight are absorbed by water molecules in the ocean. The reason the ocean is blue is due to the absorption and scattering of light. The blue wavelengths of light are scattered, similar to the
Explanation :
The name "equinox" is derived from the Latin aequus (equal) and nox (night), because around the equinox, the night and day have approximately equal length. An equinox occurs twice a year (around 20 March and 22 September), when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator. The term equinox can also be used in a broader sense, meaning the date when such a passage happens.
[24] After long periods of use, a grey spot develops on the inside of a bulb. This is because –
A.
the tungsten filament evaporates and collects there
B.
the heat of the bulb scorches the glass at the top
C.
dust inside the bulb condenses on the top
D.
glass undergoes a change due to the heat
Ans:
dust inside the bulb condenses on the top
Explanation :
At high operating temperatures, tungsten evaporates from the filament and gradually forms a gray film on the inside of the bulb. The inert gas atoms collide with the evaporating tungsten, causing some of the tungsten atoms to return to the filament. Eventually, however, a thin spot develops in the filament. When this happens, the filament will break and the bulb fails.
[25] The blue colour of water in the sea is due to –
A.
absorption of other colours except blue by water molecules
B.
scattering of blue light by water molecules
C.
reflection of blue light by impurities in sea water
D.
reflection of blue sky by sea water
Ans:
absorption of other colours except blue by water molecules
Explanation :
Almost all sunlight that enters the ocean is absorbed, except very close to the coast. The red, yellow, and green wavelengths of sunlight are absorbed by water molecules in the ocean. The reason the ocean is blue is due to the absorption and scattering of light. The blue wavelengths of light are scattered, similar to the
Explanation :
Almost all sunlight that enters the ocean is absorbed, except very close to the coast. The red, yellow, and green wavelengths of sunlight are absorbed by water molecules in the ocean. The reason the ocean is blue is due to the absorption and scattering of light. The blue wavelengths of light are scattered, similar to the