[1] The threshold frequency is the frequency below which -
A.
photo current is constant
B.
photo current increases with voltage
C.
photo current decreases with volt
D.
photo electric emission is not possible
Ans:
photo electric emission is not possible
Explanation :
The photoelectric effect is the emission of electrons by substances, especially metals, when light falls on their surfaces. The photoelectric effect will not occur when the frequency of the incident light is less than the threshold frequency as the electrons are unable to gain sufficient energy to overcome the electrostatic barrier of the work function of the metal.
[2] Oil rises up the wick in a lamp because –
A.
Oil is very light
B.
Of the diffusion of oil through the wick
C.
Of the surface tension phenomenon
D.
Of the capillary action phenomenon
Ans:
Of the capillary action phenomenon
Explanation :
It is because of the capillary action phenomenon because of which oil rise up the wick in a lamp. Capillary action, or capillarity, is the ability of a liquid to flow in narrow spaces without the assistance of, and in opposition to external forces like gravity. The effect can be seen in the drawing up of liquids between the hairs of a paint-brush, in a thin tube, in porous materials such as paper, in some non- porous materials such as liquefied carbon fiber, or in a cell.
[3] The velocity of sound in moist air is more than in dry air because the moist air has –
A.
less density than city air
B.
less pressure than dry air
C.
more pressure than dry air
D.
more density than dry air
Ans:
less density than city air
Explanation :
The density of dry air is more than that of moist air (when moisture is removed from air, its density. increases). The speed of sound in a medium is inversely proportional to the square root of its density. Therefore, the speed of sound in moist air is more than that in dry air.
[4] The owl can see most clearly in total darkness because –
A.
it has squint eyes
B.
it has large eyes with orbs directed forward, giving it binocular sight
C.
it has light bulbs in its eyes provided by nature
D.
it produces infrasonic sounds
Ans:
it has large eyes with orbs directed forward, giving it binocular sight
Explanation :
Because of their eyes, an owl can see much better in the dark than we can. Owls have very large eyes which maximize light gathering in conditions of minimum light, thereby enabling them to see at night. The orbs of their eyes are directed forward, giving them binocular vision. They are able to see their prey in a three-dimensional manner. However, an owl's eye cannot rotate.
[5] Water boils at a lower temperature on the hills because –
A.
it is cold on the hills
B.
there is less carbon dioxide on the hills
C.
there is a decrease in air pressure on the hills
D.
There is less oxygen
Ans:
there is a decrease in air pressure on the hills
Explanation :
Water boils at a lower temperature on top of a mountain because there is less air pressure on the molecules. Water boils when the vapor pressure of water exceeds atmospheric pressure. Because the boiling temperature is lower at high elevations foods that are cooked by boiling take a little longer to cook at high elevation.
[6] Bats can sense obstacles because they produce –
A.
supersonic sound waves
B.
ultrasonic sound waves
C.
infrasonic sound waves
D.
micro sound waves
Ans:
ultrasonic sound waves
Explanation :
The reason that bats use ultrasound is because it has such a high frequency and it has a low diffraction or it bends less. They use this sound to do a couple of things like to catch their prey and also just to get around. The method of doing such tasks is called echolocation. They make a sound and wait for it to bounce back to hear it. If they hear it come faster in a particular area than the rest of the sounds then they know that something is near.
[7] A satellite in vacuum -
A.
is kept in orbit by remote control
B.
is kept in orbit by retro-rocket
C.
derives energy from gravitational fielod
D.
does not require any energy for orbiting
Ans:
does not require any energy for orbiting
Explanation :
0
[8] The sky appears blue because –
A.
All colours interfere to produce blue
B.
In white light, the blue component dominates
C.
The atmosphere scatters blue colour more than the others
D.
It is actually blue
Ans:
The atmosphere scatters blue colour more than the others
Explanation :
Diffuse sky radiation is solar radiation reaching the Earth's surface after having been scattered from the direct solar beam by molecules in the atmosphere. Of the total light removed from the direct solar beam by scattering in the atmosphere (approximately 25% of the incident radiation when the sun is high in the Sky.
[9] Mercury is commonly used as a thermometric fluid rather than water because
A.
specific heat of mercury is less than water
B.
specific heat of mercury is more than water
C.
mercury has greater visibility than water
D.
density of mercury is more than the water
Ans:
mercury has greater visibility than water
Explanation :
One special kind of mercury-in-glass thermometer, called a maximum thermometer, works by having a constriction in the neck close to the bulb.
[10] A barometer is kept inside a bell jar. Air is slowly pumped out of the jar.
A.
The mercury level starts rising
B.
The mercury level starts falling
C.
The mercury level does not change
D.
The bell jar breaks up
Ans:
The mercury level starts rising
Explanation :
As the pump removes the air from the bell jar the pressure obviously reduces around the barometer. The reduction in pressure around the barometer leads it to expand. As the pump removes air from the jar, the mercury level rises.
[11] Melting point of ice _.
A.
increases with increase of pressure
B.
decreases with increase of pressure
C.
is independent of pressure
D.
None of these
Ans:
decreases with increase of pressure
Explanation :
The melting point of ice at 1 atmosphere of pressure is very close to 0 °C (32 °F, 273.15 K); this is also known as the ice point.
[12] The threshold frequency is the frequency below which –
A.
photo current increases with voltage
B.
photo current decreases with voltage
C.
photo electric emission is not possible
D.
photo current is constant
Ans:
photo electric emission is not possible
Explanation :
The photoelectric effect is the emission of electrons by substances, especially metals, when light falls on their surfaces. The photoelectric effect will not occur when the frequency of the incident light is less than the threshold frequency as the electrons are unable to gain sufficient energy to overcome the electrostatic barrier of the work function of the metal.
[13] The blue colour of sky is due to –
A.
reflection of sunlight
B.
refraction of sunlight
C.
scattering of shorter wave-lengths of sunlight in the atmosphere
D.
scattering of longer wave-lengths of sunlight in the atmosphere
Ans:
scattering of shorter wave-lengths of sunlight in the atmosphere
Explanation :
The blue colour of the sky is caused by the scattering of sunlight off the molecules of the atmosphere. This scattering, called Rayleigh scattering is more effective at short wavelengths (the blue end of the visible spectrum). Therefore the light scattered down to the earth at a large angle with respect to the direction of the sun's light is predominantly in the blue end of the spectrum.
[14] Metal tea pots have wooden handles because –
A.
wood is a bad conductor of heat
B.
it prevents electric shock
C.
it gives beauty to the pots
D.
it is hygienic
Ans:
it prevents electric shock
Explanation :
Wood is a bad conductor of heat due to the arrangement of its molecules. As the molecules of wood are far from each other, they cannot pass heat through them.
[15] Flywheel is an important part of a steam engine because it –
A.
accelerates the speed of the engine
B.
helps the engine in keeping the speed uniform
C.
decreases the moment of inertia
D.
gives strength to the engine
Ans:
helps the engine in keeping the speed uniform
Explanation :
A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a. significant moment of inertia and thus resist changes in rotational speed, enabling the engine to run at a constant, uniform motion. In the Industrial Revolution, James Watt contributed to the development of the flywheel in the steam engine.
[16] The rice is cooked more quickly in a pressure cooker because –
A.
it is covered.
B.
less quantity of water is used.
C.
None of these
D.
water boils at a higher temperature under pressure.
Ans:
water boils at a higher temperature under pressure.
Explanation :
The rice can be cooked faster in a pressure cooker since the boiling point of water increases with pressure. In general, the higher the temperature of the water, the faster the food will cook. The temperature of the water in a pressure cooker is higher than temperature of the water in an open pot.
[17] Photophobia is -
A.
a disease caused by too much sunlight
B.
abnormal intolerance of light
C.
the adjustment of the eye for light
D.
the ability to perceive light
Ans:
the adjustment of the eye for light
Explanation :
Photophobia, or light sensitivity, is an intolerance of light. Sources such as sunlight, fluorescent light and incandescent light all can cause discomfort, along with a need to squint or close your eyes.
[18] Where do the electrical charges reside in a charged conductor?
A.
at the core
B.
throughout the body
C.
depended upon the nature of the body
D.
outer surface of the body
Ans:
outer surface of the body
Explanation :
In all conductors, charges reside on the surface. The reason for this is that conductors have free electrons, that is, the electrons are loosely attached to the nucleus of the atoms in the conductors. When a solid conductor in equilibrium carries a net charge, the charge resides on the outer surface of the conductor. Besides, the electric field just, outside the conductor is perpendicular to the surface and that the field inside is zero.
[19] On a cold day when the room temperature is 15°C, the metallic cap of a pen becomes much colder than its plastic body, though both are at the same temperature of 15°C, because –
A.
metals have higher thermal capacity than plastics
B.
plastics have a lower density than metals
C.
metals are good conductors of heat
D.
plastics have a higher thermal conductivity than metals
Ans:
metals are good conductors of heat
Explanation :
On a chilly day, the room temperature is lower than our body temperature. Since metals have a higher coefficient of thermal conductivity than plastic, they are better conductor of heat than plastic. So, when we touch the metal cap and the plastic body of a pen, heat from our fingers will flow to the metal cap much more quickly than to the plastic body.
[20] The apparent weight of a person in a lift which is moving down with uniform acceleration is .
A.
greater than the weight when the person is stationary
B.
twice the weight when the person is stationary
C.
less than the weight when the person is stationary
D.
same as the weight when the person is stationary
Ans:
less than the weight when the person is stationary
Explanation :
0
[21] Air Quality Index is -
A.
an air pollutant measuring machine
B.
a measuring scale to show quality of air
C.
used for measuring humidity level
D.
used for forecasting rain
Ans:
a measuring scale to show quality of air
Explanation :
The AQI is an index for reporting daily air quality. It tells us how clean or polluted our air is, and what associated health effects might be a concern for us.
[22] If we want to calculate the pressure of a liquid at the bottom of a vessel, the quantity which is not required to determine it, is –
A.
Height of the liquid column
B.
Surface area of the bottom of the vessel
C.
Density of the liquid
D.
Acceleration due to gravity at the bottom of the vessel
Ans:
Surface area of the bottom of the vessel
Explanation :
The pressure exerted by a static fluid depends only upon the depth of the fluid, the density of the fluid, and the acceleration of gravity.
[23] It is easy to burst a gas-filled balloon with a needle than with a nail. It is because –
A.
nail is more longer than needle.
B.
nail exerts more pressure than needle on the balloon.
C.
needle exerts more pressure than nail on the balloon.
D.
gas is reactive with the needle.
Ans:
needle exerts more pressure than nail on the balloon.
Explanation :
It is easy to burst a gas-filled balloon with a needle than with a nail because the needle applies more pressure than nail. Besides, the application of the pressure is on a small surface area than in the case of nail. In the case of needle, it is a very tiny area at the tip of the needle, so only a little force gives a lot of pressure (pressure = force/area).
[24] For a body floating in water, the apparent weight is equal to -
A.
Actual weight of the body
B.
Zero
C.
Weight of the body minus weight of the liquid
D.
Weight of the body plus upward thrust
Ans:
Weight of the body minus weight of the liquid
Explanation :
0
[25] The characteristic invalid for heat radiation is that it travels –
A.
in a straight line
B.
in all directions
C.
with the speed of light
D.
heating the medium through which it passes
Ans:
with the speed of light
Explanation :
Heat is a form of energy. An important property of heat is that it flows from a body at higher temperature to another body at lower temperature.
Explanation :
The photoelectric effect is the emission of electrons by substances, especially metals, when light falls on their surfaces. The photoelectric effect will not occur when the frequency of the incident light is less than the threshold frequency as the electrons are unable to gain sufficient energy to overcome the electrostatic barrier of the work function of the metal.
[2] Oil rises up the wick in a lamp because –
A.
Oil is very light
B.
Of the diffusion of oil through the wick
C.
Of the surface tension phenomenon
D.
Of the capillary action phenomenon
Ans:
Of the capillary action phenomenon
Explanation :
It is because of the capillary action phenomenon because of which oil rise up the wick in a lamp. Capillary action, or capillarity, is the ability of a liquid to flow in narrow spaces without the assistance of, and in opposition to external forces like gravity. The effect can be seen in the drawing up of liquids between the hairs of a paint-brush, in a thin tube, in porous materials such as paper, in some non- porous materials such as liquefied carbon fiber, or in a cell.
[3] The velocity of sound in moist air is more than in dry air because the moist air has –
A.
less density than city air
B.
less pressure than dry air
C.
more pressure than dry air
D.
more density than dry air
Ans:
less density than city air
Explanation :
The density of dry air is more than that of moist air (when moisture is removed from air, its density. increases). The speed of sound in a medium is inversely proportional to the square root of its density. Therefore, the speed of sound in moist air is more than that in dry air.
[4] The owl can see most clearly in total darkness because –
A.
it has squint eyes
B.
it has large eyes with orbs directed forward, giving it binocular sight
C.
it has light bulbs in its eyes provided by nature
D.
it produces infrasonic sounds
Ans:
it has large eyes with orbs directed forward, giving it binocular sight
Explanation :
Because of their eyes, an owl can see much better in the dark than we can. Owls have very large eyes which maximize light gathering in conditions of minimum light, thereby enabling them to see at night. The orbs of their eyes are directed forward, giving them binocular vision. They are able to see their prey in a three-dimensional manner. However, an owl's eye cannot rotate.
[5] Water boils at a lower temperature on the hills because –
A.
it is cold on the hills
B.
there is less carbon dioxide on the hills
C.
there is a decrease in air pressure on the hills
D.
There is less oxygen
Ans:
there is a decrease in air pressure on the hills
Explanation :
Water boils at a lower temperature on top of a mountain because there is less air pressure on the molecules. Water boils when the vapor pressure of water exceeds atmospheric pressure. Because the boiling temperature is lower at high elevations foods that are cooked by boiling take a little longer to cook at high elevation.
[6] Bats can sense obstacles because they produce –
A.
supersonic sound waves
B.
ultrasonic sound waves
C.
infrasonic sound waves
D.
micro sound waves
Ans:
ultrasonic sound waves
Explanation :
The reason that bats use ultrasound is because it has such a high frequency and it has a low diffraction or it bends less. They use this sound to do a couple of things like to catch their prey and also just to get around. The method of doing such tasks is called echolocation. They make a sound and wait for it to bounce back to hear it. If they hear it come faster in a particular area than the rest of the sounds then they know that something is near.
[7] A satellite in vacuum -
A.
is kept in orbit by remote control
B.
is kept in orbit by retro-rocket
C.
derives energy from gravitational fielod
D.
does not require any energy for orbiting
Ans:
does not require any energy for orbiting
Explanation :
0
[8] The sky appears blue because –
A.
All colours interfere to produce blue
B.
In white light, the blue component dominates
C.
The atmosphere scatters blue colour more than the others
D.
It is actually blue
Ans:
The atmosphere scatters blue colour more than the others
Explanation :
Diffuse sky radiation is solar radiation reaching the Earth's surface after having been scattered from the direct solar beam by molecules in the atmosphere. Of the total light removed from the direct solar beam by scattering in the atmosphere (approximately 25% of the incident radiation when the sun is high in the Sky.
[9] Mercury is commonly used as a thermometric fluid rather than water because
A.
specific heat of mercury is less than water
B.
specific heat of mercury is more than water
C.
mercury has greater visibility than water
D.
density of mercury is more than the water
Ans:
mercury has greater visibility than water
Explanation :
One special kind of mercury-in-glass thermometer, called a maximum thermometer, works by having a constriction in the neck close to the bulb.
[10] A barometer is kept inside a bell jar. Air is slowly pumped out of the jar.
A.
The mercury level starts rising
B.
The mercury level starts falling
C.
The mercury level does not change
D.
The bell jar breaks up
Ans:
The mercury level starts rising
Explanation :
As the pump removes the air from the bell jar the pressure obviously reduces around the barometer. The reduction in pressure around the barometer leads it to expand. As the pump removes air from the jar, the mercury level rises.
[11] Melting point of ice _.
A.
increases with increase of pressure
B.
decreases with increase of pressure
C.
is independent of pressure
D.
None of these
Ans:
decreases with increase of pressure
Explanation :
The melting point of ice at 1 atmosphere of pressure is very close to 0 °C (32 °F, 273.15 K); this is also known as the ice point.
[12] The threshold frequency is the frequency below which –
A.
photo current increases with voltage
B.
photo current decreases with voltage
C.
photo electric emission is not possible
D.
photo current is constant
Ans:
photo electric emission is not possible
Explanation :
The photoelectric effect is the emission of electrons by substances, especially metals, when light falls on their surfaces. The photoelectric effect will not occur when the frequency of the incident light is less than the threshold frequency as the electrons are unable to gain sufficient energy to overcome the electrostatic barrier of the work function of the metal.
[13] The blue colour of sky is due to –
A.
reflection of sunlight
B.
refraction of sunlight
C.
scattering of shorter wave-lengths of sunlight in the atmosphere
D.
scattering of longer wave-lengths of sunlight in the atmosphere
Ans:
scattering of shorter wave-lengths of sunlight in the atmosphere
Explanation :
The blue colour of the sky is caused by the scattering of sunlight off the molecules of the atmosphere. This scattering, called Rayleigh scattering is more effective at short wavelengths (the blue end of the visible spectrum). Therefore the light scattered down to the earth at a large angle with respect to the direction of the sun's light is predominantly in the blue end of the spectrum.
[14] Metal tea pots have wooden handles because –
A.
wood is a bad conductor of heat
B.
it prevents electric shock
C.
it gives beauty to the pots
D.
it is hygienic
Ans:
it prevents electric shock
Explanation :
Wood is a bad conductor of heat due to the arrangement of its molecules. As the molecules of wood are far from each other, they cannot pass heat through them.
[15] Flywheel is an important part of a steam engine because it –
A.
accelerates the speed of the engine
B.
helps the engine in keeping the speed uniform
C.
decreases the moment of inertia
D.
gives strength to the engine
Ans:
helps the engine in keeping the speed uniform
Explanation :
A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a. significant moment of inertia and thus resist changes in rotational speed, enabling the engine to run at a constant, uniform motion. In the Industrial Revolution, James Watt contributed to the development of the flywheel in the steam engine.
[16] The rice is cooked more quickly in a pressure cooker because –
A.
it is covered.
B.
less quantity of water is used.
C.
None of these
D.
water boils at a higher temperature under pressure.
Ans:
water boils at a higher temperature under pressure.
Explanation :
The rice can be cooked faster in a pressure cooker since the boiling point of water increases with pressure. In general, the higher the temperature of the water, the faster the food will cook. The temperature of the water in a pressure cooker is higher than temperature of the water in an open pot.
[17] Photophobia is -
A.
a disease caused by too much sunlight
B.
abnormal intolerance of light
C.
the adjustment of the eye for light
D.
the ability to perceive light
Ans:
the adjustment of the eye for light
Explanation :
Photophobia, or light sensitivity, is an intolerance of light. Sources such as sunlight, fluorescent light and incandescent light all can cause discomfort, along with a need to squint or close your eyes.
[18] Where do the electrical charges reside in a charged conductor?
A.
at the core
B.
throughout the body
C.
depended upon the nature of the body
D.
outer surface of the body
Ans:
outer surface of the body
Explanation :
In all conductors, charges reside on the surface. The reason for this is that conductors have free electrons, that is, the electrons are loosely attached to the nucleus of the atoms in the conductors. When a solid conductor in equilibrium carries a net charge, the charge resides on the outer surface of the conductor. Besides, the electric field just, outside the conductor is perpendicular to the surface and that the field inside is zero.
[19] On a cold day when the room temperature is 15°C, the metallic cap of a pen becomes much colder than its plastic body, though both are at the same temperature of 15°C, because –
A.
metals have higher thermal capacity than plastics
B.
plastics have a lower density than metals
C.
metals are good conductors of heat
D.
plastics have a higher thermal conductivity than metals
Ans:
metals are good conductors of heat
Explanation :
On a chilly day, the room temperature is lower than our body temperature. Since metals have a higher coefficient of thermal conductivity than plastic, they are better conductor of heat than plastic. So, when we touch the metal cap and the plastic body of a pen, heat from our fingers will flow to the metal cap much more quickly than to the plastic body.
[20] The apparent weight of a person in a lift which is moving down with uniform acceleration is .
A.
greater than the weight when the person is stationary
B.
twice the weight when the person is stationary
C.
less than the weight when the person is stationary
D.
same as the weight when the person is stationary
Ans:
less than the weight when the person is stationary
Explanation :
0
[21] Air Quality Index is -
A.
an air pollutant measuring machine
B.
a measuring scale to show quality of air
C.
used for measuring humidity level
D.
used for forecasting rain
Ans:
a measuring scale to show quality of air
Explanation :
The AQI is an index for reporting daily air quality. It tells us how clean or polluted our air is, and what associated health effects might be a concern for us.
[22] If we want to calculate the pressure of a liquid at the bottom of a vessel, the quantity which is not required to determine it, is –
A.
Height of the liquid column
B.
Surface area of the bottom of the vessel
C.
Density of the liquid
D.
Acceleration due to gravity at the bottom of the vessel
Ans:
Surface area of the bottom of the vessel
Explanation :
The pressure exerted by a static fluid depends only upon the depth of the fluid, the density of the fluid, and the acceleration of gravity.
[23] It is easy to burst a gas-filled balloon with a needle than with a nail. It is because –
A.
nail is more longer than needle.
B.
nail exerts more pressure than needle on the balloon.
C.
needle exerts more pressure than nail on the balloon.
D.
gas is reactive with the needle.
Ans:
needle exerts more pressure than nail on the balloon.
Explanation :
It is easy to burst a gas-filled balloon with a needle than with a nail because the needle applies more pressure than nail. Besides, the application of the pressure is on a small surface area than in the case of nail. In the case of needle, it is a very tiny area at the tip of the needle, so only a little force gives a lot of pressure (pressure = force/area).
[24] For a body floating in water, the apparent weight is equal to -
A.
Actual weight of the body
B.
Zero
C.
Weight of the body minus weight of the liquid
D.
Weight of the body plus upward thrust
Ans:
Weight of the body minus weight of the liquid
Explanation :
0
[25] The characteristic invalid for heat radiation is that it travels –
A.
in a straight line
B.
in all directions
C.
with the speed of light
D.
heating the medium through which it passes
Ans:
with the speed of light
Explanation :
Heat is a form of energy. An important property of heat is that it flows from a body at higher temperature to another body at lower temperature.
Explanation :
The density of dry air is more than that of moist air (when moisture is removed from air, its density. increases). The speed of sound in a medium is inversely proportional to the square root of its density. Therefore, the speed of sound in moist air is more than that in dry air.
[4] The owl can see most clearly in total darkness because –
A.
it has squint eyes
B.
it has large eyes with orbs directed forward, giving it binocular sight
C.
it has light bulbs in its eyes provided by nature
D.
it produces infrasonic sounds
Ans:
it has large eyes with orbs directed forward, giving it binocular sight
Explanation :
Because of their eyes, an owl can see much better in the dark than we can. Owls have very large eyes which maximize light gathering in conditions of minimum light, thereby enabling them to see at night. The orbs of their eyes are directed forward, giving them binocular vision. They are able to see their prey in a three-dimensional manner. However, an owl's eye cannot rotate.
[5] Water boils at a lower temperature on the hills because –
A.
it is cold on the hills
B.
there is less carbon dioxide on the hills
C.
there is a decrease in air pressure on the hills
D.
There is less oxygen
Ans:
there is a decrease in air pressure on the hills
Explanation :
Water boils at a lower temperature on top of a mountain because there is less air pressure on the molecules. Water boils when the vapor pressure of water exceeds atmospheric pressure. Because the boiling temperature is lower at high elevations foods that are cooked by boiling take a little longer to cook at high elevation.
[6] Bats can sense obstacles because they produce –
A.
supersonic sound waves
B.
ultrasonic sound waves
C.
infrasonic sound waves
D.
micro sound waves
Ans:
ultrasonic sound waves
Explanation :
The reason that bats use ultrasound is because it has such a high frequency and it has a low diffraction or it bends less. They use this sound to do a couple of things like to catch their prey and also just to get around. The method of doing such tasks is called echolocation. They make a sound and wait for it to bounce back to hear it. If they hear it come faster in a particular area than the rest of the sounds then they know that something is near.
[7] A satellite in vacuum -
A.
is kept in orbit by remote control
B.
is kept in orbit by retro-rocket
C.
derives energy from gravitational fielod
D.
does not require any energy for orbiting
Ans:
does not require any energy for orbiting
Explanation :
0
[8] The sky appears blue because –
A.
All colours interfere to produce blue
B.
In white light, the blue component dominates
C.
The atmosphere scatters blue colour more than the others
D.
It is actually blue
Ans:
The atmosphere scatters blue colour more than the others
Explanation :
Diffuse sky radiation is solar radiation reaching the Earth's surface after having been scattered from the direct solar beam by molecules in the atmosphere. Of the total light removed from the direct solar beam by scattering in the atmosphere (approximately 25% of the incident radiation when the sun is high in the Sky.
[9] Mercury is commonly used as a thermometric fluid rather than water because
A.
specific heat of mercury is less than water
B.
specific heat of mercury is more than water
C.
mercury has greater visibility than water
D.
density of mercury is more than the water
Ans:
mercury has greater visibility than water
Explanation :
One special kind of mercury-in-glass thermometer, called a maximum thermometer, works by having a constriction in the neck close to the bulb.
[10] A barometer is kept inside a bell jar. Air is slowly pumped out of the jar.
A.
The mercury level starts rising
B.
The mercury level starts falling
C.
The mercury level does not change
D.
The bell jar breaks up
Ans:
The mercury level starts rising
Explanation :
As the pump removes the air from the bell jar the pressure obviously reduces around the barometer. The reduction in pressure around the barometer leads it to expand. As the pump removes air from the jar, the mercury level rises.
[11] Melting point of ice _.
A.
increases with increase of pressure
B.
decreases with increase of pressure
C.
is independent of pressure
D.
None of these
Ans:
decreases with increase of pressure
Explanation :
The melting point of ice at 1 atmosphere of pressure is very close to 0 °C (32 °F, 273.15 K); this is also known as the ice point.
[12] The threshold frequency is the frequency below which –
A.
photo current increases with voltage
B.
photo current decreases with voltage
C.
photo electric emission is not possible
D.
photo current is constant
Ans:
photo electric emission is not possible
Explanation :
The photoelectric effect is the emission of electrons by substances, especially metals, when light falls on their surfaces. The photoelectric effect will not occur when the frequency of the incident light is less than the threshold frequency as the electrons are unable to gain sufficient energy to overcome the electrostatic barrier of the work function of the metal.
[13] The blue colour of sky is due to –
A.
reflection of sunlight
B.
refraction of sunlight
C.
scattering of shorter wave-lengths of sunlight in the atmosphere
D.
scattering of longer wave-lengths of sunlight in the atmosphere
Ans:
scattering of shorter wave-lengths of sunlight in the atmosphere
Explanation :
The blue colour of the sky is caused by the scattering of sunlight off the molecules of the atmosphere. This scattering, called Rayleigh scattering is more effective at short wavelengths (the blue end of the visible spectrum). Therefore the light scattered down to the earth at a large angle with respect to the direction of the sun's light is predominantly in the blue end of the spectrum.
[14] Metal tea pots have wooden handles because –
A.
wood is a bad conductor of heat
B.
it prevents electric shock
C.
it gives beauty to the pots
D.
it is hygienic
Ans:
it prevents electric shock
Explanation :
Wood is a bad conductor of heat due to the arrangement of its molecules. As the molecules of wood are far from each other, they cannot pass heat through them.
[15] Flywheel is an important part of a steam engine because it –
A.
accelerates the speed of the engine
B.
helps the engine in keeping the speed uniform
C.
decreases the moment of inertia
D.
gives strength to the engine
Ans:
helps the engine in keeping the speed uniform
Explanation :
A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a. significant moment of inertia and thus resist changes in rotational speed, enabling the engine to run at a constant, uniform motion. In the Industrial Revolution, James Watt contributed to the development of the flywheel in the steam engine.
[16] The rice is cooked more quickly in a pressure cooker because –
A.
it is covered.
B.
less quantity of water is used.
C.
None of these
D.
water boils at a higher temperature under pressure.
Ans:
water boils at a higher temperature under pressure.
Explanation :
The rice can be cooked faster in a pressure cooker since the boiling point of water increases with pressure. In general, the higher the temperature of the water, the faster the food will cook. The temperature of the water in a pressure cooker is higher than temperature of the water in an open pot.
[17] Photophobia is -
A.
a disease caused by too much sunlight
B.
abnormal intolerance of light
C.
the adjustment of the eye for light
D.
the ability to perceive light
Ans:
the adjustment of the eye for light
Explanation :
Photophobia, or light sensitivity, is an intolerance of light. Sources such as sunlight, fluorescent light and incandescent light all can cause discomfort, along with a need to squint or close your eyes.
[18] Where do the electrical charges reside in a charged conductor?
A.
at the core
B.
throughout the body
C.
depended upon the nature of the body
D.
outer surface of the body
Ans:
outer surface of the body
Explanation :
In all conductors, charges reside on the surface. The reason for this is that conductors have free electrons, that is, the electrons are loosely attached to the nucleus of the atoms in the conductors. When a solid conductor in equilibrium carries a net charge, the charge resides on the outer surface of the conductor. Besides, the electric field just, outside the conductor is perpendicular to the surface and that the field inside is zero.
[19] On a cold day when the room temperature is 15°C, the metallic cap of a pen becomes much colder than its plastic body, though both are at the same temperature of 15°C, because –
A.
metals have higher thermal capacity than plastics
B.
plastics have a lower density than metals
C.
metals are good conductors of heat
D.
plastics have a higher thermal conductivity than metals
Ans:
metals are good conductors of heat
Explanation :
On a chilly day, the room temperature is lower than our body temperature. Since metals have a higher coefficient of thermal conductivity than plastic, they are better conductor of heat than plastic. So, when we touch the metal cap and the plastic body of a pen, heat from our fingers will flow to the metal cap much more quickly than to the plastic body.
[20] The apparent weight of a person in a lift which is moving down with uniform acceleration is .
A.
greater than the weight when the person is stationary
B.
twice the weight when the person is stationary
C.
less than the weight when the person is stationary
D.
same as the weight when the person is stationary
Ans:
less than the weight when the person is stationary
Explanation :
0
[21] Air Quality Index is -
A.
an air pollutant measuring machine
B.
a measuring scale to show quality of air
C.
used for measuring humidity level
D.
used for forecasting rain
Ans:
a measuring scale to show quality of air
Explanation :
The AQI is an index for reporting daily air quality. It tells us how clean or polluted our air is, and what associated health effects might be a concern for us.
[22] If we want to calculate the pressure of a liquid at the bottom of a vessel, the quantity which is not required to determine it, is –
A.
Height of the liquid column
B.
Surface area of the bottom of the vessel
C.
Density of the liquid
D.
Acceleration due to gravity at the bottom of the vessel
Ans:
Surface area of the bottom of the vessel
Explanation :
The pressure exerted by a static fluid depends only upon the depth of the fluid, the density of the fluid, and the acceleration of gravity.
[23] It is easy to burst a gas-filled balloon with a needle than with a nail. It is because –
A.
nail is more longer than needle.
B.
nail exerts more pressure than needle on the balloon.
C.
needle exerts more pressure than nail on the balloon.
D.
gas is reactive with the needle.
Ans:
needle exerts more pressure than nail on the balloon.
Explanation :
It is easy to burst a gas-filled balloon with a needle than with a nail because the needle applies more pressure than nail. Besides, the application of the pressure is on a small surface area than in the case of nail. In the case of needle, it is a very tiny area at the tip of the needle, so only a little force gives a lot of pressure (pressure = force/area).
[24] For a body floating in water, the apparent weight is equal to -
A.
Actual weight of the body
B.
Zero
C.
Weight of the body minus weight of the liquid
D.
Weight of the body plus upward thrust
Ans:
Weight of the body minus weight of the liquid
Explanation :
0
[25] The characteristic invalid for heat radiation is that it travels –
A.
in a straight line
B.
in all directions
C.
with the speed of light
D.
heating the medium through which it passes
Ans:
with the speed of light
Explanation :
Heat is a form of energy. An important property of heat is that it flows from a body at higher temperature to another body at lower temperature.
Explanation :
Water boils at a lower temperature on top of a mountain because there is less air pressure on the molecules. Water boils when the vapor pressure of water exceeds atmospheric pressure. Because the boiling temperature is lower at high elevations foods that are cooked by boiling take a little longer to cook at high elevation.
[6] Bats can sense obstacles because they produce –
A.
supersonic sound waves
B.
ultrasonic sound waves
C.
infrasonic sound waves
D.
micro sound waves
Ans:
ultrasonic sound waves
Explanation :
The reason that bats use ultrasound is because it has such a high frequency and it has a low diffraction or it bends less. They use this sound to do a couple of things like to catch their prey and also just to get around. The method of doing such tasks is called echolocation. They make a sound and wait for it to bounce back to hear it. If they hear it come faster in a particular area than the rest of the sounds then they know that something is near.
[7] A satellite in vacuum -
A.
is kept in orbit by remote control
B.
is kept in orbit by retro-rocket
C.
derives energy from gravitational fielod
D.
does not require any energy for orbiting
Ans:
does not require any energy for orbiting
Explanation :
0
[8] The sky appears blue because –
A.
All colours interfere to produce blue
B.
In white light, the blue component dominates
C.
The atmosphere scatters blue colour more than the others
D.
It is actually blue
Ans:
The atmosphere scatters blue colour more than the others
Explanation :
Diffuse sky radiation is solar radiation reaching the Earth's surface after having been scattered from the direct solar beam by molecules in the atmosphere. Of the total light removed from the direct solar beam by scattering in the atmosphere (approximately 25% of the incident radiation when the sun is high in the Sky.
[9] Mercury is commonly used as a thermometric fluid rather than water because
A.
specific heat of mercury is less than water
B.
specific heat of mercury is more than water
C.
mercury has greater visibility than water
D.
density of mercury is more than the water
Ans:
mercury has greater visibility than water
Explanation :
One special kind of mercury-in-glass thermometer, called a maximum thermometer, works by having a constriction in the neck close to the bulb.
[10] A barometer is kept inside a bell jar. Air is slowly pumped out of the jar.
A.
The mercury level starts rising
B.
The mercury level starts falling
C.
The mercury level does not change
D.
The bell jar breaks up
Ans:
The mercury level starts rising
Explanation :
As the pump removes the air from the bell jar the pressure obviously reduces around the barometer. The reduction in pressure around the barometer leads it to expand. As the pump removes air from the jar, the mercury level rises.
[11] Melting point of ice _.
A.
increases with increase of pressure
B.
decreases with increase of pressure
C.
is independent of pressure
D.
None of these
Ans:
decreases with increase of pressure
Explanation :
The melting point of ice at 1 atmosphere of pressure is very close to 0 °C (32 °F, 273.15 K); this is also known as the ice point.
[12] The threshold frequency is the frequency below which –
A.
photo current increases with voltage
B.
photo current decreases with voltage
C.
photo electric emission is not possible
D.
photo current is constant
Ans:
photo electric emission is not possible
Explanation :
The photoelectric effect is the emission of electrons by substances, especially metals, when light falls on their surfaces. The photoelectric effect will not occur when the frequency of the incident light is less than the threshold frequency as the electrons are unable to gain sufficient energy to overcome the electrostatic barrier of the work function of the metal.
[13] The blue colour of sky is due to –
A.
reflection of sunlight
B.
refraction of sunlight
C.
scattering of shorter wave-lengths of sunlight in the atmosphere
D.
scattering of longer wave-lengths of sunlight in the atmosphere
Ans:
scattering of shorter wave-lengths of sunlight in the atmosphere
Explanation :
The blue colour of the sky is caused by the scattering of sunlight off the molecules of the atmosphere. This scattering, called Rayleigh scattering is more effective at short wavelengths (the blue end of the visible spectrum). Therefore the light scattered down to the earth at a large angle with respect to the direction of the sun's light is predominantly in the blue end of the spectrum.
[14] Metal tea pots have wooden handles because –
A.
wood is a bad conductor of heat
B.
it prevents electric shock
C.
it gives beauty to the pots
D.
it is hygienic
Ans:
it prevents electric shock
Explanation :
Wood is a bad conductor of heat due to the arrangement of its molecules. As the molecules of wood are far from each other, they cannot pass heat through them.
[15] Flywheel is an important part of a steam engine because it –
A.
accelerates the speed of the engine
B.
helps the engine in keeping the speed uniform
C.
decreases the moment of inertia
D.
gives strength to the engine
Ans:
helps the engine in keeping the speed uniform
Explanation :
A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a. significant moment of inertia and thus resist changes in rotational speed, enabling the engine to run at a constant, uniform motion. In the Industrial Revolution, James Watt contributed to the development of the flywheel in the steam engine.
[16] The rice is cooked more quickly in a pressure cooker because –
A.
it is covered.
B.
less quantity of water is used.
C.
None of these
D.
water boils at a higher temperature under pressure.
Ans:
water boils at a higher temperature under pressure.
Explanation :
The rice can be cooked faster in a pressure cooker since the boiling point of water increases with pressure. In general, the higher the temperature of the water, the faster the food will cook. The temperature of the water in a pressure cooker is higher than temperature of the water in an open pot.
[17] Photophobia is -
A.
a disease caused by too much sunlight
B.
abnormal intolerance of light
C.
the adjustment of the eye for light
D.
the ability to perceive light
Ans:
the adjustment of the eye for light
Explanation :
Photophobia, or light sensitivity, is an intolerance of light. Sources such as sunlight, fluorescent light and incandescent light all can cause discomfort, along with a need to squint or close your eyes.
[18] Where do the electrical charges reside in a charged conductor?
A.
at the core
B.
throughout the body
C.
depended upon the nature of the body
D.
outer surface of the body
Ans:
outer surface of the body
Explanation :
In all conductors, charges reside on the surface. The reason for this is that conductors have free electrons, that is, the electrons are loosely attached to the nucleus of the atoms in the conductors. When a solid conductor in equilibrium carries a net charge, the charge resides on the outer surface of the conductor. Besides, the electric field just, outside the conductor is perpendicular to the surface and that the field inside is zero.
[19] On a cold day when the room temperature is 15°C, the metallic cap of a pen becomes much colder than its plastic body, though both are at the same temperature of 15°C, because –
A.
metals have higher thermal capacity than plastics
B.
plastics have a lower density than metals
C.
metals are good conductors of heat
D.
plastics have a higher thermal conductivity than metals
Ans:
metals are good conductors of heat
Explanation :
On a chilly day, the room temperature is lower than our body temperature. Since metals have a higher coefficient of thermal conductivity than plastic, they are better conductor of heat than plastic. So, when we touch the metal cap and the plastic body of a pen, heat from our fingers will flow to the metal cap much more quickly than to the plastic body.
[20] The apparent weight of a person in a lift which is moving down with uniform acceleration is .
A.
greater than the weight when the person is stationary
B.
twice the weight when the person is stationary
C.
less than the weight when the person is stationary
D.
same as the weight when the person is stationary
Ans:
less than the weight when the person is stationary
Explanation :
0
[21] Air Quality Index is -
A.
an air pollutant measuring machine
B.
a measuring scale to show quality of air
C.
used for measuring humidity level
D.
used for forecasting rain
Ans:
a measuring scale to show quality of air
Explanation :
The AQI is an index for reporting daily air quality. It tells us how clean or polluted our air is, and what associated health effects might be a concern for us.
[22] If we want to calculate the pressure of a liquid at the bottom of a vessel, the quantity which is not required to determine it, is –
A.
Height of the liquid column
B.
Surface area of the bottom of the vessel
C.
Density of the liquid
D.
Acceleration due to gravity at the bottom of the vessel
Ans:
Surface area of the bottom of the vessel
Explanation :
The pressure exerted by a static fluid depends only upon the depth of the fluid, the density of the fluid, and the acceleration of gravity.
[23] It is easy to burst a gas-filled balloon with a needle than with a nail. It is because –
A.
nail is more longer than needle.
B.
nail exerts more pressure than needle on the balloon.
C.
needle exerts more pressure than nail on the balloon.
D.
gas is reactive with the needle.
Ans:
needle exerts more pressure than nail on the balloon.
Explanation :
It is easy to burst a gas-filled balloon with a needle than with a nail because the needle applies more pressure than nail. Besides, the application of the pressure is on a small surface area than in the case of nail. In the case of needle, it is a very tiny area at the tip of the needle, so only a little force gives a lot of pressure (pressure = force/area).
[24] For a body floating in water, the apparent weight is equal to -
A.
Actual weight of the body
B.
Zero
C.
Weight of the body minus weight of the liquid
D.
Weight of the body plus upward thrust
Ans:
Weight of the body minus weight of the liquid
Explanation :
0
[25] The characteristic invalid for heat radiation is that it travels –
A.
in a straight line
B.
in all directions
C.
with the speed of light
D.
heating the medium through which it passes
Ans:
with the speed of light
Explanation :
Heat is a form of energy. An important property of heat is that it flows from a body at higher temperature to another body at lower temperature.
Explanation :
0
[8] The sky appears blue because –
A.
All colours interfere to produce blue
B.
In white light, the blue component dominates
C.
The atmosphere scatters blue colour more than the others
D.
It is actually blue
Ans:
The atmosphere scatters blue colour more than the others
Explanation :
Diffuse sky radiation is solar radiation reaching the Earth's surface after having been scattered from the direct solar beam by molecules in the atmosphere. Of the total light removed from the direct solar beam by scattering in the atmosphere (approximately 25% of the incident radiation when the sun is high in the Sky.
[9] Mercury is commonly used as a thermometric fluid rather than water because
A.
specific heat of mercury is less than water
B.
specific heat of mercury is more than water
C.
mercury has greater visibility than water
D.
density of mercury is more than the water
Ans:
mercury has greater visibility than water
Explanation :
One special kind of mercury-in-glass thermometer, called a maximum thermometer, works by having a constriction in the neck close to the bulb.
[10] A barometer is kept inside a bell jar. Air is slowly pumped out of the jar.
A.
The mercury level starts rising
B.
The mercury level starts falling
C.
The mercury level does not change
D.
The bell jar breaks up
Ans:
The mercury level starts rising
Explanation :
As the pump removes the air from the bell jar the pressure obviously reduces around the barometer. The reduction in pressure around the barometer leads it to expand. As the pump removes air from the jar, the mercury level rises.
[11] Melting point of ice _.
A.
increases with increase of pressure
B.
decreases with increase of pressure
C.
is independent of pressure
D.
None of these
Ans:
decreases with increase of pressure
Explanation :
The melting point of ice at 1 atmosphere of pressure is very close to 0 °C (32 °F, 273.15 K); this is also known as the ice point.
[12] The threshold frequency is the frequency below which –
A.
photo current increases with voltage
B.
photo current decreases with voltage
C.
photo electric emission is not possible
D.
photo current is constant
Ans:
photo electric emission is not possible
Explanation :
The photoelectric effect is the emission of electrons by substances, especially metals, when light falls on their surfaces. The photoelectric effect will not occur when the frequency of the incident light is less than the threshold frequency as the electrons are unable to gain sufficient energy to overcome the electrostatic barrier of the work function of the metal.
[13] The blue colour of sky is due to –
A.
reflection of sunlight
B.
refraction of sunlight
C.
scattering of shorter wave-lengths of sunlight in the atmosphere
D.
scattering of longer wave-lengths of sunlight in the atmosphere
Ans:
scattering of shorter wave-lengths of sunlight in the atmosphere
Explanation :
The blue colour of the sky is caused by the scattering of sunlight off the molecules of the atmosphere. This scattering, called Rayleigh scattering is more effective at short wavelengths (the blue end of the visible spectrum). Therefore the light scattered down to the earth at a large angle with respect to the direction of the sun's light is predominantly in the blue end of the spectrum.
[14] Metal tea pots have wooden handles because –
A.
wood is a bad conductor of heat
B.
it prevents electric shock
C.
it gives beauty to the pots
D.
it is hygienic
Ans:
it prevents electric shock
Explanation :
Wood is a bad conductor of heat due to the arrangement of its molecules. As the molecules of wood are far from each other, they cannot pass heat through them.
[15] Flywheel is an important part of a steam engine because it –
A.
accelerates the speed of the engine
B.
helps the engine in keeping the speed uniform
C.
decreases the moment of inertia
D.
gives strength to the engine
Ans:
helps the engine in keeping the speed uniform
Explanation :
A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a. significant moment of inertia and thus resist changes in rotational speed, enabling the engine to run at a constant, uniform motion. In the Industrial Revolution, James Watt contributed to the development of the flywheel in the steam engine.
[16] The rice is cooked more quickly in a pressure cooker because –
A.
it is covered.
B.
less quantity of water is used.
C.
None of these
D.
water boils at a higher temperature under pressure.
Ans:
water boils at a higher temperature under pressure.
Explanation :
The rice can be cooked faster in a pressure cooker since the boiling point of water increases with pressure. In general, the higher the temperature of the water, the faster the food will cook. The temperature of the water in a pressure cooker is higher than temperature of the water in an open pot.
[17] Photophobia is -
A.
a disease caused by too much sunlight
B.
abnormal intolerance of light
C.
the adjustment of the eye for light
D.
the ability to perceive light
Ans:
the adjustment of the eye for light
Explanation :
Photophobia, or light sensitivity, is an intolerance of light. Sources such as sunlight, fluorescent light and incandescent light all can cause discomfort, along with a need to squint or close your eyes.
[18] Where do the electrical charges reside in a charged conductor?
A.
at the core
B.
throughout the body
C.
depended upon the nature of the body
D.
outer surface of the body
Ans:
outer surface of the body
Explanation :
In all conductors, charges reside on the surface. The reason for this is that conductors have free electrons, that is, the electrons are loosely attached to the nucleus of the atoms in the conductors. When a solid conductor in equilibrium carries a net charge, the charge resides on the outer surface of the conductor. Besides, the electric field just, outside the conductor is perpendicular to the surface and that the field inside is zero.
[19] On a cold day when the room temperature is 15°C, the metallic cap of a pen becomes much colder than its plastic body, though both are at the same temperature of 15°C, because –
A.
metals have higher thermal capacity than plastics
B.
plastics have a lower density than metals
C.
metals are good conductors of heat
D.
plastics have a higher thermal conductivity than metals
Ans:
metals are good conductors of heat
Explanation :
On a chilly day, the room temperature is lower than our body temperature. Since metals have a higher coefficient of thermal conductivity than plastic, they are better conductor of heat than plastic. So, when we touch the metal cap and the plastic body of a pen, heat from our fingers will flow to the metal cap much more quickly than to the plastic body.
[20] The apparent weight of a person in a lift which is moving down with uniform acceleration is .
A.
greater than the weight when the person is stationary
B.
twice the weight when the person is stationary
C.
less than the weight when the person is stationary
D.
same as the weight when the person is stationary
Ans:
less than the weight when the person is stationary
Explanation :
0
[21] Air Quality Index is -
A.
an air pollutant measuring machine
B.
a measuring scale to show quality of air
C.
used for measuring humidity level
D.
used for forecasting rain
Ans:
a measuring scale to show quality of air
Explanation :
The AQI is an index for reporting daily air quality. It tells us how clean or polluted our air is, and what associated health effects might be a concern for us.
[22] If we want to calculate the pressure of a liquid at the bottom of a vessel, the quantity which is not required to determine it, is –
A.
Height of the liquid column
B.
Surface area of the bottom of the vessel
C.
Density of the liquid
D.
Acceleration due to gravity at the bottom of the vessel
Ans:
Surface area of the bottom of the vessel
Explanation :
The pressure exerted by a static fluid depends only upon the depth of the fluid, the density of the fluid, and the acceleration of gravity.
[23] It is easy to burst a gas-filled balloon with a needle than with a nail. It is because –
A.
nail is more longer than needle.
B.
nail exerts more pressure than needle on the balloon.
C.
needle exerts more pressure than nail on the balloon.
D.
gas is reactive with the needle.
Ans:
needle exerts more pressure than nail on the balloon.
Explanation :
It is easy to burst a gas-filled balloon with a needle than with a nail because the needle applies more pressure than nail. Besides, the application of the pressure is on a small surface area than in the case of nail. In the case of needle, it is a very tiny area at the tip of the needle, so only a little force gives a lot of pressure (pressure = force/area).
[24] For a body floating in water, the apparent weight is equal to -
A.
Actual weight of the body
B.
Zero
C.
Weight of the body minus weight of the liquid
D.
Weight of the body plus upward thrust
Ans:
Weight of the body minus weight of the liquid
Explanation :
0
[25] The characteristic invalid for heat radiation is that it travels –
A.
in a straight line
B.
in all directions
C.
with the speed of light
D.
heating the medium through which it passes
Ans:
with the speed of light
Explanation :
Heat is a form of energy. An important property of heat is that it flows from a body at higher temperature to another body at lower temperature.
Explanation :
One special kind of mercury-in-glass thermometer, called a maximum thermometer, works by having a constriction in the neck close to the bulb.
[10] A barometer is kept inside a bell jar. Air is slowly pumped out of the jar.
A.
The mercury level starts rising
B.
The mercury level starts falling
C.
The mercury level does not change
D.
The bell jar breaks up
Ans:
The mercury level starts rising
Explanation :
As the pump removes the air from the bell jar the pressure obviously reduces around the barometer. The reduction in pressure around the barometer leads it to expand. As the pump removes air from the jar, the mercury level rises.
[11] Melting point of ice _.
A.
increases with increase of pressure
B.
decreases with increase of pressure
C.
is independent of pressure
D.
None of these
Ans:
decreases with increase of pressure
Explanation :
The melting point of ice at 1 atmosphere of pressure is very close to 0 °C (32 °F, 273.15 K); this is also known as the ice point.
[12] The threshold frequency is the frequency below which –
A.
photo current increases with voltage
B.
photo current decreases with voltage
C.
photo electric emission is not possible
D.
photo current is constant
Ans:
photo electric emission is not possible
Explanation :
The photoelectric effect is the emission of electrons by substances, especially metals, when light falls on their surfaces. The photoelectric effect will not occur when the frequency of the incident light is less than the threshold frequency as the electrons are unable to gain sufficient energy to overcome the electrostatic barrier of the work function of the metal.
[13] The blue colour of sky is due to –
A.
reflection of sunlight
B.
refraction of sunlight
C.
scattering of shorter wave-lengths of sunlight in the atmosphere
D.
scattering of longer wave-lengths of sunlight in the atmosphere
Ans:
scattering of shorter wave-lengths of sunlight in the atmosphere
Explanation :
The blue colour of the sky is caused by the scattering of sunlight off the molecules of the atmosphere. This scattering, called Rayleigh scattering is more effective at short wavelengths (the blue end of the visible spectrum). Therefore the light scattered down to the earth at a large angle with respect to the direction of the sun's light is predominantly in the blue end of the spectrum.
[14] Metal tea pots have wooden handles because –
A.
wood is a bad conductor of heat
B.
it prevents electric shock
C.
it gives beauty to the pots
D.
it is hygienic
Ans:
it prevents electric shock
Explanation :
Wood is a bad conductor of heat due to the arrangement of its molecules. As the molecules of wood are far from each other, they cannot pass heat through them.
[15] Flywheel is an important part of a steam engine because it –
A.
accelerates the speed of the engine
B.
helps the engine in keeping the speed uniform
C.
decreases the moment of inertia
D.
gives strength to the engine
Ans:
helps the engine in keeping the speed uniform
Explanation :
A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a. significant moment of inertia and thus resist changes in rotational speed, enabling the engine to run at a constant, uniform motion. In the Industrial Revolution, James Watt contributed to the development of the flywheel in the steam engine.
[16] The rice is cooked more quickly in a pressure cooker because –
A.
it is covered.
B.
less quantity of water is used.
C.
None of these
D.
water boils at a higher temperature under pressure.
Ans:
water boils at a higher temperature under pressure.
Explanation :
The rice can be cooked faster in a pressure cooker since the boiling point of water increases with pressure. In general, the higher the temperature of the water, the faster the food will cook. The temperature of the water in a pressure cooker is higher than temperature of the water in an open pot.
[17] Photophobia is -
A.
a disease caused by too much sunlight
B.
abnormal intolerance of light
C.
the adjustment of the eye for light
D.
the ability to perceive light
Ans:
the adjustment of the eye for light
Explanation :
Photophobia, or light sensitivity, is an intolerance of light. Sources such as sunlight, fluorescent light and incandescent light all can cause discomfort, along with a need to squint or close your eyes.
[18] Where do the electrical charges reside in a charged conductor?
A.
at the core
B.
throughout the body
C.
depended upon the nature of the body
D.
outer surface of the body
Ans:
outer surface of the body
Explanation :
In all conductors, charges reside on the surface. The reason for this is that conductors have free electrons, that is, the electrons are loosely attached to the nucleus of the atoms in the conductors. When a solid conductor in equilibrium carries a net charge, the charge resides on the outer surface of the conductor. Besides, the electric field just, outside the conductor is perpendicular to the surface and that the field inside is zero.
[19] On a cold day when the room temperature is 15°C, the metallic cap of a pen becomes much colder than its plastic body, though both are at the same temperature of 15°C, because –
A.
metals have higher thermal capacity than plastics
B.
plastics have a lower density than metals
C.
metals are good conductors of heat
D.
plastics have a higher thermal conductivity than metals
Ans:
metals are good conductors of heat
Explanation :
On a chilly day, the room temperature is lower than our body temperature. Since metals have a higher coefficient of thermal conductivity than plastic, they are better conductor of heat than plastic. So, when we touch the metal cap and the plastic body of a pen, heat from our fingers will flow to the metal cap much more quickly than to the plastic body.
[20] The apparent weight of a person in a lift which is moving down with uniform acceleration is .
A.
greater than the weight when the person is stationary
B.
twice the weight when the person is stationary
C.
less than the weight when the person is stationary
D.
same as the weight when the person is stationary
Ans:
less than the weight when the person is stationary
Explanation :
0
[21] Air Quality Index is -
A.
an air pollutant measuring machine
B.
a measuring scale to show quality of air
C.
used for measuring humidity level
D.
used for forecasting rain
Ans:
a measuring scale to show quality of air
Explanation :
The AQI is an index for reporting daily air quality. It tells us how clean or polluted our air is, and what associated health effects might be a concern for us.
[22] If we want to calculate the pressure of a liquid at the bottom of a vessel, the quantity which is not required to determine it, is –
A.
Height of the liquid column
B.
Surface area of the bottom of the vessel
C.
Density of the liquid
D.
Acceleration due to gravity at the bottom of the vessel
Ans:
Surface area of the bottom of the vessel
Explanation :
The pressure exerted by a static fluid depends only upon the depth of the fluid, the density of the fluid, and the acceleration of gravity.
[23] It is easy to burst a gas-filled balloon with a needle than with a nail. It is because –
A.
nail is more longer than needle.
B.
nail exerts more pressure than needle on the balloon.
C.
needle exerts more pressure than nail on the balloon.
D.
gas is reactive with the needle.
Ans:
needle exerts more pressure than nail on the balloon.
Explanation :
It is easy to burst a gas-filled balloon with a needle than with a nail because the needle applies more pressure than nail. Besides, the application of the pressure is on a small surface area than in the case of nail. In the case of needle, it is a very tiny area at the tip of the needle, so only a little force gives a lot of pressure (pressure = force/area).
[24] For a body floating in water, the apparent weight is equal to -
A.
Actual weight of the body
B.
Zero
C.
Weight of the body minus weight of the liquid
D.
Weight of the body plus upward thrust
Ans:
Weight of the body minus weight of the liquid
Explanation :
0
[25] The characteristic invalid for heat radiation is that it travels –
A.
in a straight line
B.
in all directions
C.
with the speed of light
D.
heating the medium through which it passes
Ans:
with the speed of light
Explanation :
Heat is a form of energy. An important property of heat is that it flows from a body at higher temperature to another body at lower temperature.
Explanation :
The melting point of ice at 1 atmosphere of pressure is very close to 0 °C (32 °F, 273.15 K); this is also known as the ice point.
[12] The threshold frequency is the frequency below which –
A.
photo current increases with voltage
B.
photo current decreases with voltage
C.
photo electric emission is not possible
D.
photo current is constant
Ans:
photo electric emission is not possible
Explanation :
The photoelectric effect is the emission of electrons by substances, especially metals, when light falls on their surfaces. The photoelectric effect will not occur when the frequency of the incident light is less than the threshold frequency as the electrons are unable to gain sufficient energy to overcome the electrostatic barrier of the work function of the metal.
[13] The blue colour of sky is due to –
A.
reflection of sunlight
B.
refraction of sunlight
C.
scattering of shorter wave-lengths of sunlight in the atmosphere
D.
scattering of longer wave-lengths of sunlight in the atmosphere
Ans:
scattering of shorter wave-lengths of sunlight in the atmosphere
Explanation :
The blue colour of the sky is caused by the scattering of sunlight off the molecules of the atmosphere. This scattering, called Rayleigh scattering is more effective at short wavelengths (the blue end of the visible spectrum). Therefore the light scattered down to the earth at a large angle with respect to the direction of the sun's light is predominantly in the blue end of the spectrum.
[14] Metal tea pots have wooden handles because –
A.
wood is a bad conductor of heat
B.
it prevents electric shock
C.
it gives beauty to the pots
D.
it is hygienic
Ans:
it prevents electric shock
Explanation :
Wood is a bad conductor of heat due to the arrangement of its molecules. As the molecules of wood are far from each other, they cannot pass heat through them.
[15] Flywheel is an important part of a steam engine because it –
A.
accelerates the speed of the engine
B.
helps the engine in keeping the speed uniform
C.
decreases the moment of inertia
D.
gives strength to the engine
Ans:
helps the engine in keeping the speed uniform
Explanation :
A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a. significant moment of inertia and thus resist changes in rotational speed, enabling the engine to run at a constant, uniform motion. In the Industrial Revolution, James Watt contributed to the development of the flywheel in the steam engine.
[16] The rice is cooked more quickly in a pressure cooker because –
A.
it is covered.
B.
less quantity of water is used.
C.
None of these
D.
water boils at a higher temperature under pressure.
Ans:
water boils at a higher temperature under pressure.
Explanation :
The rice can be cooked faster in a pressure cooker since the boiling point of water increases with pressure. In general, the higher the temperature of the water, the faster the food will cook. The temperature of the water in a pressure cooker is higher than temperature of the water in an open pot.
[17] Photophobia is -
A.
a disease caused by too much sunlight
B.
abnormal intolerance of light
C.
the adjustment of the eye for light
D.
the ability to perceive light
Ans:
the adjustment of the eye for light
Explanation :
Photophobia, or light sensitivity, is an intolerance of light. Sources such as sunlight, fluorescent light and incandescent light all can cause discomfort, along with a need to squint or close your eyes.
[18] Where do the electrical charges reside in a charged conductor?
A.
at the core
B.
throughout the body
C.
depended upon the nature of the body
D.
outer surface of the body
Ans:
outer surface of the body
Explanation :
In all conductors, charges reside on the surface. The reason for this is that conductors have free electrons, that is, the electrons are loosely attached to the nucleus of the atoms in the conductors. When a solid conductor in equilibrium carries a net charge, the charge resides on the outer surface of the conductor. Besides, the electric field just, outside the conductor is perpendicular to the surface and that the field inside is zero.
[19] On a cold day when the room temperature is 15°C, the metallic cap of a pen becomes much colder than its plastic body, though both are at the same temperature of 15°C, because –
A.
metals have higher thermal capacity than plastics
B.
plastics have a lower density than metals
C.
metals are good conductors of heat
D.
plastics have a higher thermal conductivity than metals
Ans:
metals are good conductors of heat
Explanation :
On a chilly day, the room temperature is lower than our body temperature. Since metals have a higher coefficient of thermal conductivity than plastic, they are better conductor of heat than plastic. So, when we touch the metal cap and the plastic body of a pen, heat from our fingers will flow to the metal cap much more quickly than to the plastic body.
[20] The apparent weight of a person in a lift which is moving down with uniform acceleration is .
A.
greater than the weight when the person is stationary
B.
twice the weight when the person is stationary
C.
less than the weight when the person is stationary
D.
same as the weight when the person is stationary
Ans:
less than the weight when the person is stationary
Explanation :
0
[21] Air Quality Index is -
A.
an air pollutant measuring machine
B.
a measuring scale to show quality of air
C.
used for measuring humidity level
D.
used for forecasting rain
Ans:
a measuring scale to show quality of air
Explanation :
The AQI is an index for reporting daily air quality. It tells us how clean or polluted our air is, and what associated health effects might be a concern for us.
[22] If we want to calculate the pressure of a liquid at the bottom of a vessel, the quantity which is not required to determine it, is –
A.
Height of the liquid column
B.
Surface area of the bottom of the vessel
C.
Density of the liquid
D.
Acceleration due to gravity at the bottom of the vessel
Ans:
Surface area of the bottom of the vessel
Explanation :
The pressure exerted by a static fluid depends only upon the depth of the fluid, the density of the fluid, and the acceleration of gravity.
[23] It is easy to burst a gas-filled balloon with a needle than with a nail. It is because –
A.
nail is more longer than needle.
B.
nail exerts more pressure than needle on the balloon.
C.
needle exerts more pressure than nail on the balloon.
D.
gas is reactive with the needle.
Ans:
needle exerts more pressure than nail on the balloon.
Explanation :
It is easy to burst a gas-filled balloon with a needle than with a nail because the needle applies more pressure than nail. Besides, the application of the pressure is on a small surface area than in the case of nail. In the case of needle, it is a very tiny area at the tip of the needle, so only a little force gives a lot of pressure (pressure = force/area).
[24] For a body floating in water, the apparent weight is equal to -
A.
Actual weight of the body
B.
Zero
C.
Weight of the body minus weight of the liquid
D.
Weight of the body plus upward thrust
Ans:
Weight of the body minus weight of the liquid
Explanation :
0
[25] The characteristic invalid for heat radiation is that it travels –
A.
in a straight line
B.
in all directions
C.
with the speed of light
D.
heating the medium through which it passes
Ans:
with the speed of light
Explanation :
Heat is a form of energy. An important property of heat is that it flows from a body at higher temperature to another body at lower temperature.
Explanation :
The blue colour of the sky is caused by the scattering of sunlight off the molecules of the atmosphere. This scattering, called Rayleigh scattering is more effective at short wavelengths (the blue end of the visible spectrum). Therefore the light scattered down to the earth at a large angle with respect to the direction of the sun's light is predominantly in the blue end of the spectrum.
[14] Metal tea pots have wooden handles because –
A.
wood is a bad conductor of heat
B.
it prevents electric shock
C.
it gives beauty to the pots
D.
it is hygienic
Ans:
it prevents electric shock
Explanation :
Wood is a bad conductor of heat due to the arrangement of its molecules. As the molecules of wood are far from each other, they cannot pass heat through them.
[15] Flywheel is an important part of a steam engine because it –
A.
accelerates the speed of the engine
B.
helps the engine in keeping the speed uniform
C.
decreases the moment of inertia
D.
gives strength to the engine
Ans:
helps the engine in keeping the speed uniform
Explanation :
A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a. significant moment of inertia and thus resist changes in rotational speed, enabling the engine to run at a constant, uniform motion. In the Industrial Revolution, James Watt contributed to the development of the flywheel in the steam engine.
[16] The rice is cooked more quickly in a pressure cooker because –
A.
it is covered.
B.
less quantity of water is used.
C.
None of these
D.
water boils at a higher temperature under pressure.
Ans:
water boils at a higher temperature under pressure.
Explanation :
The rice can be cooked faster in a pressure cooker since the boiling point of water increases with pressure. In general, the higher the temperature of the water, the faster the food will cook. The temperature of the water in a pressure cooker is higher than temperature of the water in an open pot.
[17] Photophobia is -
A.
a disease caused by too much sunlight
B.
abnormal intolerance of light
C.
the adjustment of the eye for light
D.
the ability to perceive light
Ans:
the adjustment of the eye for light
Explanation :
Photophobia, or light sensitivity, is an intolerance of light. Sources such as sunlight, fluorescent light and incandescent light all can cause discomfort, along with a need to squint or close your eyes.
[18] Where do the electrical charges reside in a charged conductor?
A.
at the core
B.
throughout the body
C.
depended upon the nature of the body
D.
outer surface of the body
Ans:
outer surface of the body
Explanation :
In all conductors, charges reside on the surface. The reason for this is that conductors have free electrons, that is, the electrons are loosely attached to the nucleus of the atoms in the conductors. When a solid conductor in equilibrium carries a net charge, the charge resides on the outer surface of the conductor. Besides, the electric field just, outside the conductor is perpendicular to the surface and that the field inside is zero.
[19] On a cold day when the room temperature is 15°C, the metallic cap of a pen becomes much colder than its plastic body, though both are at the same temperature of 15°C, because –
A.
metals have higher thermal capacity than plastics
B.
plastics have a lower density than metals
C.
metals are good conductors of heat
D.
plastics have a higher thermal conductivity than metals
Ans:
metals are good conductors of heat
Explanation :
On a chilly day, the room temperature is lower than our body temperature. Since metals have a higher coefficient of thermal conductivity than plastic, they are better conductor of heat than plastic. So, when we touch the metal cap and the plastic body of a pen, heat from our fingers will flow to the metal cap much more quickly than to the plastic body.
[20] The apparent weight of a person in a lift which is moving down with uniform acceleration is .
A.
greater than the weight when the person is stationary
B.
twice the weight when the person is stationary
C.
less than the weight when the person is stationary
D.
same as the weight when the person is stationary
Ans:
less than the weight when the person is stationary
Explanation :
0
[21] Air Quality Index is -
A.
an air pollutant measuring machine
B.
a measuring scale to show quality of air
C.
used for measuring humidity level
D.
used for forecasting rain
Ans:
a measuring scale to show quality of air
Explanation :
The AQI is an index for reporting daily air quality. It tells us how clean or polluted our air is, and what associated health effects might be a concern for us.
[22] If we want to calculate the pressure of a liquid at the bottom of a vessel, the quantity which is not required to determine it, is –
A.
Height of the liquid column
B.
Surface area of the bottom of the vessel
C.
Density of the liquid
D.
Acceleration due to gravity at the bottom of the vessel
Ans:
Surface area of the bottom of the vessel
Explanation :
The pressure exerted by a static fluid depends only upon the depth of the fluid, the density of the fluid, and the acceleration of gravity.
[23] It is easy to burst a gas-filled balloon with a needle than with a nail. It is because –
A.
nail is more longer than needle.
B.
nail exerts more pressure than needle on the balloon.
C.
needle exerts more pressure than nail on the balloon.
D.
gas is reactive with the needle.
Ans:
needle exerts more pressure than nail on the balloon.
Explanation :
It is easy to burst a gas-filled balloon with a needle than with a nail because the needle applies more pressure than nail. Besides, the application of the pressure is on a small surface area than in the case of nail. In the case of needle, it is a very tiny area at the tip of the needle, so only a little force gives a lot of pressure (pressure = force/area).
[24] For a body floating in water, the apparent weight is equal to -
A.
Actual weight of the body
B.
Zero
C.
Weight of the body minus weight of the liquid
D.
Weight of the body plus upward thrust
Ans:
Weight of the body minus weight of the liquid
Explanation :
0
[25] The characteristic invalid for heat radiation is that it travels –
A.
in a straight line
B.
in all directions
C.
with the speed of light
D.
heating the medium through which it passes
Ans:
with the speed of light
Explanation :
Heat is a form of energy. An important property of heat is that it flows from a body at higher temperature to another body at lower temperature.
Explanation :
A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a. significant moment of inertia and thus resist changes in rotational speed, enabling the engine to run at a constant, uniform motion. In the Industrial Revolution, James Watt contributed to the development of the flywheel in the steam engine.
[16] The rice is cooked more quickly in a pressure cooker because –
A.
it is covered.
B.
less quantity of water is used.
C.
None of these
D.
water boils at a higher temperature under pressure.
Ans:
water boils at a higher temperature under pressure.
Explanation :
The rice can be cooked faster in a pressure cooker since the boiling point of water increases with pressure. In general, the higher the temperature of the water, the faster the food will cook. The temperature of the water in a pressure cooker is higher than temperature of the water in an open pot.
[17] Photophobia is -
A.
a disease caused by too much sunlight
B.
abnormal intolerance of light
C.
the adjustment of the eye for light
D.
the ability to perceive light
Ans:
the adjustment of the eye for light
Explanation :
Photophobia, or light sensitivity, is an intolerance of light. Sources such as sunlight, fluorescent light and incandescent light all can cause discomfort, along with a need to squint or close your eyes.
[18] Where do the electrical charges reside in a charged conductor?
A.
at the core
B.
throughout the body
C.
depended upon the nature of the body
D.
outer surface of the body
Ans:
outer surface of the body
Explanation :
In all conductors, charges reside on the surface. The reason for this is that conductors have free electrons, that is, the electrons are loosely attached to the nucleus of the atoms in the conductors. When a solid conductor in equilibrium carries a net charge, the charge resides on the outer surface of the conductor. Besides, the electric field just, outside the conductor is perpendicular to the surface and that the field inside is zero.
[19] On a cold day when the room temperature is 15°C, the metallic cap of a pen becomes much colder than its plastic body, though both are at the same temperature of 15°C, because –
A.
metals have higher thermal capacity than plastics
B.
plastics have a lower density than metals
C.
metals are good conductors of heat
D.
plastics have a higher thermal conductivity than metals
Ans:
metals are good conductors of heat
Explanation :
On a chilly day, the room temperature is lower than our body temperature. Since metals have a higher coefficient of thermal conductivity than plastic, they are better conductor of heat than plastic. So, when we touch the metal cap and the plastic body of a pen, heat from our fingers will flow to the metal cap much more quickly than to the plastic body.
[20] The apparent weight of a person in a lift which is moving down with uniform acceleration is .
A.
greater than the weight when the person is stationary
B.
twice the weight when the person is stationary
C.
less than the weight when the person is stationary
D.
same as the weight when the person is stationary
Ans:
less than the weight when the person is stationary
Explanation :
0
[21] Air Quality Index is -
A.
an air pollutant measuring machine
B.
a measuring scale to show quality of air
C.
used for measuring humidity level
D.
used for forecasting rain
Ans:
a measuring scale to show quality of air
Explanation :
The AQI is an index for reporting daily air quality. It tells us how clean or polluted our air is, and what associated health effects might be a concern for us.
[22] If we want to calculate the pressure of a liquid at the bottom of a vessel, the quantity which is not required to determine it, is –
A.
Height of the liquid column
B.
Surface area of the bottom of the vessel
C.
Density of the liquid
D.
Acceleration due to gravity at the bottom of the vessel
Ans:
Surface area of the bottom of the vessel
Explanation :
The pressure exerted by a static fluid depends only upon the depth of the fluid, the density of the fluid, and the acceleration of gravity.
[23] It is easy to burst a gas-filled balloon with a needle than with a nail. It is because –
A.
nail is more longer than needle.
B.
nail exerts more pressure than needle on the balloon.
C.
needle exerts more pressure than nail on the balloon.
D.
gas is reactive with the needle.
Ans:
needle exerts more pressure than nail on the balloon.
Explanation :
It is easy to burst a gas-filled balloon with a needle than with a nail because the needle applies more pressure than nail. Besides, the application of the pressure is on a small surface area than in the case of nail. In the case of needle, it is a very tiny area at the tip of the needle, so only a little force gives a lot of pressure (pressure = force/area).
[24] For a body floating in water, the apparent weight is equal to -
A.
Actual weight of the body
B.
Zero
C.
Weight of the body minus weight of the liquid
D.
Weight of the body plus upward thrust
Ans:
Weight of the body minus weight of the liquid
Explanation :
0
[25] The characteristic invalid for heat radiation is that it travels –
A.
in a straight line
B.
in all directions
C.
with the speed of light
D.
heating the medium through which it passes
Ans:
with the speed of light
Explanation :
Heat is a form of energy. An important property of heat is that it flows from a body at higher temperature to another body at lower temperature.
Explanation :
Photophobia, or light sensitivity, is an intolerance of light. Sources such as sunlight, fluorescent light and incandescent light all can cause discomfort, along with a need to squint or close your eyes.
[18] Where do the electrical charges reside in a charged conductor?
A.
at the core
B.
throughout the body
C.
depended upon the nature of the body
D.
outer surface of the body
Ans:
outer surface of the body
Explanation :
In all conductors, charges reside on the surface. The reason for this is that conductors have free electrons, that is, the electrons are loosely attached to the nucleus of the atoms in the conductors. When a solid conductor in equilibrium carries a net charge, the charge resides on the outer surface of the conductor. Besides, the electric field just, outside the conductor is perpendicular to the surface and that the field inside is zero.
[19] On a cold day when the room temperature is 15°C, the metallic cap of a pen becomes much colder than its plastic body, though both are at the same temperature of 15°C, because –
A.
metals have higher thermal capacity than plastics
B.
plastics have a lower density than metals
C.
metals are good conductors of heat
D.
plastics have a higher thermal conductivity than metals
Ans:
metals are good conductors of heat
Explanation :
On a chilly day, the room temperature is lower than our body temperature. Since metals have a higher coefficient of thermal conductivity than plastic, they are better conductor of heat than plastic. So, when we touch the metal cap and the plastic body of a pen, heat from our fingers will flow to the metal cap much more quickly than to the plastic body.
[20] The apparent weight of a person in a lift which is moving down with uniform acceleration is .
A.
greater than the weight when the person is stationary
B.
twice the weight when the person is stationary
C.
less than the weight when the person is stationary
D.
same as the weight when the person is stationary
Ans:
less than the weight when the person is stationary
Explanation :
0
[21] Air Quality Index is -
A.
an air pollutant measuring machine
B.
a measuring scale to show quality of air
C.
used for measuring humidity level
D.
used for forecasting rain
Ans:
a measuring scale to show quality of air
Explanation :
The AQI is an index for reporting daily air quality. It tells us how clean or polluted our air is, and what associated health effects might be a concern for us.
[22] If we want to calculate the pressure of a liquid at the bottom of a vessel, the quantity which is not required to determine it, is –
A.
Height of the liquid column
B.
Surface area of the bottom of the vessel
C.
Density of the liquid
D.
Acceleration due to gravity at the bottom of the vessel
Ans:
Surface area of the bottom of the vessel
Explanation :
The pressure exerted by a static fluid depends only upon the depth of the fluid, the density of the fluid, and the acceleration of gravity.
[23] It is easy to burst a gas-filled balloon with a needle than with a nail. It is because –
A.
nail is more longer than needle.
B.
nail exerts more pressure than needle on the balloon.
C.
needle exerts more pressure than nail on the balloon.
D.
gas is reactive with the needle.
Ans:
needle exerts more pressure than nail on the balloon.
Explanation :
It is easy to burst a gas-filled balloon with a needle than with a nail because the needle applies more pressure than nail. Besides, the application of the pressure is on a small surface area than in the case of nail. In the case of needle, it is a very tiny area at the tip of the needle, so only a little force gives a lot of pressure (pressure = force/area).
[24] For a body floating in water, the apparent weight is equal to -
A.
Actual weight of the body
B.
Zero
C.
Weight of the body minus weight of the liquid
D.
Weight of the body plus upward thrust
Ans:
Weight of the body minus weight of the liquid
Explanation :
0
[25] The characteristic invalid for heat radiation is that it travels –
A.
in a straight line
B.
in all directions
C.
with the speed of light
D.
heating the medium through which it passes
Ans:
with the speed of light
Explanation :
Heat is a form of energy. An important property of heat is that it flows from a body at higher temperature to another body at lower temperature.
Explanation :
On a chilly day, the room temperature is lower than our body temperature. Since metals have a higher coefficient of thermal conductivity than plastic, they are better conductor of heat than plastic. So, when we touch the metal cap and the plastic body of a pen, heat from our fingers will flow to the metal cap much more quickly than to the plastic body.
[20] The apparent weight of a person in a lift which is moving down with uniform acceleration is .
A.
greater than the weight when the person is stationary
B.
twice the weight when the person is stationary
C.
less than the weight when the person is stationary
D.
same as the weight when the person is stationary
Ans:
less than the weight when the person is stationary
Explanation :
0
[21] Air Quality Index is -
A.
an air pollutant measuring machine
B.
a measuring scale to show quality of air
C.
used for measuring humidity level
D.
used for forecasting rain
Ans:
a measuring scale to show quality of air
Explanation :
The AQI is an index for reporting daily air quality. It tells us how clean or polluted our air is, and what associated health effects might be a concern for us.
[22] If we want to calculate the pressure of a liquid at the bottom of a vessel, the quantity which is not required to determine it, is –
A.
Height of the liquid column
B.
Surface area of the bottom of the vessel
C.
Density of the liquid
D.
Acceleration due to gravity at the bottom of the vessel
Ans:
Surface area of the bottom of the vessel
Explanation :
The pressure exerted by a static fluid depends only upon the depth of the fluid, the density of the fluid, and the acceleration of gravity.
[23] It is easy to burst a gas-filled balloon with a needle than with a nail. It is because –
A.
nail is more longer than needle.
B.
nail exerts more pressure than needle on the balloon.
C.
needle exerts more pressure than nail on the balloon.
D.
gas is reactive with the needle.
Ans:
needle exerts more pressure than nail on the balloon.
Explanation :
It is easy to burst a gas-filled balloon with a needle than with a nail because the needle applies more pressure than nail. Besides, the application of the pressure is on a small surface area than in the case of nail. In the case of needle, it is a very tiny area at the tip of the needle, so only a little force gives a lot of pressure (pressure = force/area).
[24] For a body floating in water, the apparent weight is equal to -
A.
Actual weight of the body
B.
Zero
C.
Weight of the body minus weight of the liquid
D.
Weight of the body plus upward thrust
Ans:
Weight of the body minus weight of the liquid
Explanation :
0
[25] The characteristic invalid for heat radiation is that it travels –
A.
in a straight line
B.
in all directions
C.
with the speed of light
D.
heating the medium through which it passes
Ans:
with the speed of light
Explanation :
Heat is a form of energy. An important property of heat is that it flows from a body at higher temperature to another body at lower temperature.
Explanation :
The AQI is an index for reporting daily air quality. It tells us how clean or polluted our air is, and what associated health effects might be a concern for us.
[22] If we want to calculate the pressure of a liquid at the bottom of a vessel, the quantity which is not required to determine it, is –
A.
Height of the liquid column
B.
Surface area of the bottom of the vessel
C.
Density of the liquid
D.
Acceleration due to gravity at the bottom of the vessel
Ans:
Surface area of the bottom of the vessel
Explanation :
The pressure exerted by a static fluid depends only upon the depth of the fluid, the density of the fluid, and the acceleration of gravity.
[23] It is easy to burst a gas-filled balloon with a needle than with a nail. It is because –
A.
nail is more longer than needle.
B.
nail exerts more pressure than needle on the balloon.
C.
needle exerts more pressure than nail on the balloon.
D.
gas is reactive with the needle.
Ans:
needle exerts more pressure than nail on the balloon.
Explanation :
It is easy to burst a gas-filled balloon with a needle than with a nail because the needle applies more pressure than nail. Besides, the application of the pressure is on a small surface area than in the case of nail. In the case of needle, it is a very tiny area at the tip of the needle, so only a little force gives a lot of pressure (pressure = force/area).
[24] For a body floating in water, the apparent weight is equal to -
A.
Actual weight of the body
B.
Zero
C.
Weight of the body minus weight of the liquid
D.
Weight of the body plus upward thrust
Ans:
Weight of the body minus weight of the liquid
Explanation :
0
[25] The characteristic invalid for heat radiation is that it travels –
A.
in a straight line
B.
in all directions
C.
with the speed of light
D.
heating the medium through which it passes
Ans:
with the speed of light
Explanation :
Heat is a form of energy. An important property of heat is that it flows from a body at higher temperature to another body at lower temperature.
Explanation :
It is easy to burst a gas-filled balloon with a needle than with a nail because the needle applies more pressure than nail. Besides, the application of the pressure is on a small surface area than in the case of nail. In the case of needle, it is a very tiny area at the tip of the needle, so only a little force gives a lot of pressure (pressure = force/area).
[24] For a body floating in water, the apparent weight is equal to -
A.
Actual weight of the body
B.
Zero
C.
Weight of the body minus weight of the liquid
D.
Weight of the body plus upward thrust
Ans:
Weight of the body minus weight of the liquid
Explanation :
0
[25] The characteristic invalid for heat radiation is that it travels –
A.
in a straight line
B.
in all directions
C.
with the speed of light
D.
heating the medium through which it passes
Ans:
with the speed of light
Explanation :
Heat is a form of energy. An important property of heat is that it flows from a body at higher temperature to another body at lower temperature.
Explanation :
Heat is a form of energy. An important property of heat is that it flows from a body at higher temperature to another body at lower temperature.