[1] Methanol cannot be dried with anhydrous CaCl2 because -
A.
CaCl2 dissolves in it
B.
it is not good dehydrating agent
C.
it forms a solid CaCl2 × 4CH3OH
D.
it reacts with CH3OH
Ans:
it forms a solid CaCl2 × 4CH3OH
Explanation :
0
[2] Acid rain is caused by the pollution of environment by –
A.
Carbon monoxide and Carbon dioxide
B.
Ozone and Carbon dioxide
C.
Nitrous oxide and Sulphur dioxide
D.
Carbon dioxide and Nitrogen
Ans:
Nitrous oxide and Sulphur dioxide
Explanation :
Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain. Human activities are the main cause of acid rain.
[3] What are the components responsible for acid rain?
A.
Nitrogen monoxide (NO) and Carbon monoxide (CO)
B.
Sulphur dioxide (SO2) and Nitrogen oxides (NOx)
C.
Carbon dioxide (CO2) and Carbon monoxide (CO)
D.
Oxides of carbon (COx) and Oxides of nitrogen (NOx)
Ans:
Sulphur dioxide (SO2) and Nitrogen oxides (NOx)
Explanation :
Acid rain is caused by emissions of sulfur dioxide (SO2) and nitrogen oxide (NO), which react with the water molecules in the atmosphere to produce acids. The SO2 and NOx react with water, oxygen and other chemicals to form sulfuric and nitric acids. The chemicals in acid rain can cause paint to peel, corrosion of steel structures and weathering of stone buildings.
[4] Thermal electricity is generated by using which of these?
A.
Coal only
B.
Coal and Natural Gas only
C.
Coal, Natural Gas and Petroleum
D.
None of these
Ans:
Coal, Natural Gas and Petroleum
Explanation :
A thermal power station is a power plant in which heat energy is converted to electric power. Thermal power is producing using fossil fuel such as coal, natural gas or petroleum.
[5] Synthetic detergents are made from –
A.
Sodium stearate
B.
Sodium salt of benzene sulphonic acid
C.
Sodium salt of benzene carboxylic acid
D.
Sodium palmitate
Ans:
Sodium salt of benzene sulphonic acid
Explanation :
Synthetic detergents are made from sodium salt of benezene sulphonic acid.
[6] The open "Sigrees” or coal stoves often require fanning to sustain burning because of -
A.
tendency of carbon dioxide to form a layer along with dust smoke
B.
lack of oxygen in the surroundings of sigrees
C.
accumulation of smoke and dust over the sigrees
D.
interrupted release of moisture from the material
Ans:
tendency of carbon dioxide to form a layer along with dust smoke
Explanation :
Burning coal requires oxygen to chemically react. The availability of oxygen is limited in the furnace by several factors such as the friction of the air against the coal. Blowing provides more oxygen to the flame and raises the temperature of the flame. Besides, it helps to prevent carbon dioxide from forming layer along with dust smoke so as to keep the supply of oxygen intact.
[7] Antacid tablets consist of –
A.
Hydroxides of sodium, magnesium and aluminium
B.
Hydroxides of magnesium and aluminium
C.
Hydroxides of sodium and aluminium
D.
Hydroxides of magnesium and sodium
Ans:
Hydroxides of magnesium and aluminium
Explanation :
An antacid is a base which neutralizes stomach acidity. The most common of these bases are hydroxides, carbonates, or bicarbonates such as Aluminum hydroxide, Calcium. carbonate, Magnesium carbonate, Magnesium hydroxide, and Sodium bicarbonate.
[8] Acid rain is caused by the pollution of environment by -
A.
carbon dioxide and nitrogen
B.
carbón monoxide and carbon dioxide
C.
ozone and carbon dioxide
D.
nitrous oxide and sulphur dioxide
Ans:
nitrous oxide and sulphur dioxide
Explanation :
[9] Synthetic detergents are prepared from –
A.
potassium salts of higher fatty-acids
B.
sodium salts of higher fat acids
C.
hydrocarbons of petroleum
D.
glycerides
Ans:
hydrocarbons of petroleum
Explanation :
Synthetic detergents are prepared from hydrocarbons of petroleum. They are sodium salts of long chain benzene sulphonic acids or sodium salts of long chain alkyl hydrogen sulphates. Calcium and magnesium salts of detergents are soluble in water. Therefore cleansing action of detergents remains unaffected in hard water.
[10] Metals have .
A.
High melting and boiling point
B.
Low melting and boiling point
C.
High melting and low boiling point
D.
Low melting and high boiling point
Ans:
High melting and boiling point
Explanation :
As metals are giant lattice structures, the number of electrostatic forces to be broken is extremely large, and so metals have high melting and boiling points. This means that the melting point and boiling point of metals are more similar to those for ionic compounds than for covalent substances.
[11] Soap helps in better cleaning of clothes because -
A.
Soap acts like catalyst
B.
It reduces the surface tension of solution
C.
It gives strength to solution
D.
It absorbs the dirt
Ans:
It reduces the surface tension of solution
Explanation :
Soaps are effective cleaners because they can dissolve and the oil and grease that holds dirt in place. They reduce the surface tension of the solution and enable it to wet things more uniformly. The surfactants in detergents improve water's ability to wet things, spread over surfaces, and seep into dirty clothes fibers. The surfactant molecules help water to get a hold of grease, break it up, and wash it away.
[12] Acid rain is caused by, the pollution of environment by -
A.
carbon dioxide and nitrogen
B.
carbon monoxide and carbon dioxide
C.
ozone and carbon dioxide
D.
nitrous oxide and sulphur dioxide
Ans:
carbon dioxide and nitrogen
Explanation :
0
[13] The enormous amount of energy released in an explosion of an atomic bomb is due to the -
A.
conversion of mass into energy
B.
conversion of chemical energy into heat energy
C.
conversion of mechnical energy into nuclear energy
D.
conversion of neutrons into protons
Ans:
conversion of neutrons into protons
Explanation :
The enormous amount of energy released in an explosion of an atomic bomb is due to the converson of neutrons into protons. When, a neutron strikes the nucleus of an atom of the isotopes uranium 235 or plutonium 239, it causes that nucleus to split into two fragmens, each of which is a nucleus with about half the protons and neutrons of the original nucleus.
[14] Organic food is supposed to be better for human consumption because –
A.
It is grown in glass house air tight environment
B.
It is grown without the use of chemicals & synthetic pesticides
C.
It depends on chemicals & fertilizers
D.
It is too expensive to buy
Ans:
It is grown without the use of chemicals & synthetic pesticides
Explanation :
There are at least two good arguments for eating organic: fewer pesticides and more nutrients. In the absence of pesticides and fertilizers, plants boost their production of the phytochernicals (vitamins and antioxidants) that strengthen their resistance to bugs and weeds. A major new study has found that organic foods contain higher levels of antioxidants and less harmful chemicals than conventionally farmed pro-duce.
[15] Nitrogen fixation is a process of -
A.
Assimilation of nitrate
B.
Utilisation of nitrogen gas
C.
Conversion of organic nitrogen to proteins
D.
Conversion of molecular nitrogen to ammonia
Ans:
Conversion of molecular nitrogen to ammonia
Explanation :
Nitrogen fixation is a process by which nitrogen in the Earth's atmosphere is converted into ammonia (NH3) or other molecules available to living organisms. Atmospheric nitrogen or molecular dinitrogen (N2) is relatively inert: it does not easily react with other chemicals to form new compounds. The fixation process frees nitrogen atoms from their triply bonded diatomic form, to be used by plants as nutrients. The conversion of organic nitrogen to proteins is achieved in Nitrogen cycle.
[16] What are soaps?
A.
Salts of silicates
B.
Ester of heavy fatty acids
C.
Sodium or potassium salts of heavier fatty acids
D.
Mixture of glycerol and alcohol
Ans:
Sodium or potassium salts of heavier fatty acids
Explanation :
0
[17] Electrolysis of an aqueous solution of copper sulphate using copper electrodes gives -
A.
Copper at eathode and oxygen at anode.
B.
Copper at anode and oxygen at cathode.
C.
Copper at cathode and anodes dissolve to give copper.
D.
Hydrogen at cathode and oxygen at anode.
Ans:
Copper at eathode and oxygen at anode.
Explanation :
Copper is deposited at the cathode and is dissolved at the anode. Consequently the concentration of copper ions in solution remains constant. This can be used as a method of purification of copper as only pure copper is deposited at the cathode
[18] Phosphorus is kept in water because –
A.
its ignition temperature is very high
B.
its ignition temperature is very low
C.
its critical temperature is high
D.
its critical temperature is low
Ans:
its ignition temperature is very low
Explanation :
The allotropic form of Phosphorus (white phosphorus) is less stable and therefore highly reactive because of angular strain in P4 molecule where the angles are only 600.
[19] The relation between bond length and bond energy is -
A.
Lower the bond energy, shorter the bond length
B.
They are not related
C.
Higher the bond energy, shorter the bond length
D.
Higher the bond energy, longer the bond length
Ans:
Higher the bond energy, shorter the bond length
Explanation :
Generally, the shorter the bond, the stronger the bond and the higher the dissociation energy. Bond energy is a measure of the strength in a chemical bond.
[20] In an atomic explosion enormous energy is released which is due to the -
A.
Conversions of neutrons into protons
B.
Conversion of chemical energy into nuclear energy
C.
Conversion of mechanical energy into nuclear energy
D.
Conversion of mass into energy
Ans:
Conversion of mass into energy
Explanation :
0
[21] Sea water is saltier than rain water because –
A.
Sea animals are salt producing
B.
The air around the sea is saltish
C.
Rivers wash away salts from earth and pour them into the sea
D.
Sea beds have salt producing mines
Ans:
Rivers wash away salts from earth and pour them into the sea
Explanation :
Seawater is salty because rainwater dissolves the salt minerals found in soil and rocks as it travels through rivers arid streams en route to the sea The rain that falls on the land contains some dissolved carbon dioxide from the surrounding air.
[22] Refrigerators keep food unspoiled because –
A.
at its low temperature, bacteria and moulds are inactive
B.
at its low temperature, the germs are killed
C.
at its low temperature, the germs are frozen
D.
it sterilizes the food
Ans:
at its low temperature, bacteria and moulds are inactive
Explanation :
Bacteria and moulds find conditions of low pH, moisture, or temperature and high salt or sugar unfavorable for their operation. This is the principle why refrigerators keep food unspoiled for a long time. Bacterial action is severely impaired at temperatures at or below 4 degree Celsius.
[23] Why is water not suitable for putting out a petrol fire?
A.
The oxygen content of water is isolated by petrol and thus it helps in burning
B.
Petrol is too inflammable to be extinguished by water
C.
The heat required for combustion of petrol is very low
D.
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Ans:
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Explanation :
Water is not effective on petrol fire because it has higher density than petrol as a result of which it sinks to the bottom, while petrol stays afloat and keeps burning. Petro-chemical fires are nearly always extinguished with chemical foam which forms a blanket over the flames and cuts off the oxygen supply.
[24] All isotopes of the same element have _.
A.
different atomic numbers and different atomic mass
B.
different atomic numbers and the same atomic mass
C.
the same atomic number but different atomic masses
D.
the same atomic number and the atomic mass
Ans:
the same atomic number but different atomic masses
Explanation :
Isotopes are forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei. So they have the same atomic number, but differ in relative atomic mass.
[25] Sodium vapour lamps glow with yellow colour. This is due to -
A.
sublimation of sodium to emit yellow colour
B.
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
C.
the low ionisation energy of sodium
D.
its ability to absorb all other colours except yellow
Ans:
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
Explanation :
Sodium Vapour Lamps glow with yellow colour due to the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum.
Explanation :
0
[2] Acid rain is caused by the pollution of environment by –
A.
Carbon monoxide and Carbon dioxide
B.
Ozone and Carbon dioxide
C.
Nitrous oxide and Sulphur dioxide
D.
Carbon dioxide and Nitrogen
Ans:
Nitrous oxide and Sulphur dioxide
Explanation :
Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain. Human activities are the main cause of acid rain.
[3] What are the components responsible for acid rain?
A.
Nitrogen monoxide (NO) and Carbon monoxide (CO)
B.
Sulphur dioxide (SO2) and Nitrogen oxides (NOx)
C.
Carbon dioxide (CO2) and Carbon monoxide (CO)
D.
Oxides of carbon (COx) and Oxides of nitrogen (NOx)
Ans:
Sulphur dioxide (SO2) and Nitrogen oxides (NOx)
Explanation :
Acid rain is caused by emissions of sulfur dioxide (SO2) and nitrogen oxide (NO), which react with the water molecules in the atmosphere to produce acids. The SO2 and NOx react with water, oxygen and other chemicals to form sulfuric and nitric acids. The chemicals in acid rain can cause paint to peel, corrosion of steel structures and weathering of stone buildings.
[4] Thermal electricity is generated by using which of these?
A.
Coal only
B.
Coal and Natural Gas only
C.
Coal, Natural Gas and Petroleum
D.
None of these
Ans:
Coal, Natural Gas and Petroleum
Explanation :
A thermal power station is a power plant in which heat energy is converted to electric power. Thermal power is producing using fossil fuel such as coal, natural gas or petroleum.
[5] Synthetic detergents are made from –
A.
Sodium stearate
B.
Sodium salt of benzene sulphonic acid
C.
Sodium salt of benzene carboxylic acid
D.
Sodium palmitate
Ans:
Sodium salt of benzene sulphonic acid
Explanation :
Synthetic detergents are made from sodium salt of benezene sulphonic acid.
[6] The open "Sigrees” or coal stoves often require fanning to sustain burning because of -
A.
tendency of carbon dioxide to form a layer along with dust smoke
B.
lack of oxygen in the surroundings of sigrees
C.
accumulation of smoke and dust over the sigrees
D.
interrupted release of moisture from the material
Ans:
tendency of carbon dioxide to form a layer along with dust smoke
Explanation :
Burning coal requires oxygen to chemically react. The availability of oxygen is limited in the furnace by several factors such as the friction of the air against the coal. Blowing provides more oxygen to the flame and raises the temperature of the flame. Besides, it helps to prevent carbon dioxide from forming layer along with dust smoke so as to keep the supply of oxygen intact.
[7] Antacid tablets consist of –
A.
Hydroxides of sodium, magnesium and aluminium
B.
Hydroxides of magnesium and aluminium
C.
Hydroxides of sodium and aluminium
D.
Hydroxides of magnesium and sodium
Ans:
Hydroxides of magnesium and aluminium
Explanation :
An antacid is a base which neutralizes stomach acidity. The most common of these bases are hydroxides, carbonates, or bicarbonates such as Aluminum hydroxide, Calcium. carbonate, Magnesium carbonate, Magnesium hydroxide, and Sodium bicarbonate.
[8] Acid rain is caused by the pollution of environment by -
A.
carbon dioxide and nitrogen
B.
carbón monoxide and carbon dioxide
C.
ozone and carbon dioxide
D.
nitrous oxide and sulphur dioxide
Ans:
nitrous oxide and sulphur dioxide
Explanation :
[9] Synthetic detergents are prepared from –
A.
potassium salts of higher fatty-acids
B.
sodium salts of higher fat acids
C.
hydrocarbons of petroleum
D.
glycerides
Ans:
hydrocarbons of petroleum
Explanation :
Synthetic detergents are prepared from hydrocarbons of petroleum. They are sodium salts of long chain benzene sulphonic acids or sodium salts of long chain alkyl hydrogen sulphates. Calcium and magnesium salts of detergents are soluble in water. Therefore cleansing action of detergents remains unaffected in hard water.
[10] Metals have .
A.
High melting and boiling point
B.
Low melting and boiling point
C.
High melting and low boiling point
D.
Low melting and high boiling point
Ans:
High melting and boiling point
Explanation :
As metals are giant lattice structures, the number of electrostatic forces to be broken is extremely large, and so metals have high melting and boiling points. This means that the melting point and boiling point of metals are more similar to those for ionic compounds than for covalent substances.
[11] Soap helps in better cleaning of clothes because -
A.
Soap acts like catalyst
B.
It reduces the surface tension of solution
C.
It gives strength to solution
D.
It absorbs the dirt
Ans:
It reduces the surface tension of solution
Explanation :
Soaps are effective cleaners because they can dissolve and the oil and grease that holds dirt in place. They reduce the surface tension of the solution and enable it to wet things more uniformly. The surfactants in detergents improve water's ability to wet things, spread over surfaces, and seep into dirty clothes fibers. The surfactant molecules help water to get a hold of grease, break it up, and wash it away.
[12] Acid rain is caused by, the pollution of environment by -
A.
carbon dioxide and nitrogen
B.
carbon monoxide and carbon dioxide
C.
ozone and carbon dioxide
D.
nitrous oxide and sulphur dioxide
Ans:
carbon dioxide and nitrogen
Explanation :
0
[13] The enormous amount of energy released in an explosion of an atomic bomb is due to the -
A.
conversion of mass into energy
B.
conversion of chemical energy into heat energy
C.
conversion of mechnical energy into nuclear energy
D.
conversion of neutrons into protons
Ans:
conversion of neutrons into protons
Explanation :
The enormous amount of energy released in an explosion of an atomic bomb is due to the converson of neutrons into protons. When, a neutron strikes the nucleus of an atom of the isotopes uranium 235 or plutonium 239, it causes that nucleus to split into two fragmens, each of which is a nucleus with about half the protons and neutrons of the original nucleus.
[14] Organic food is supposed to be better for human consumption because –
A.
It is grown in glass house air tight environment
B.
It is grown without the use of chemicals & synthetic pesticides
C.
It depends on chemicals & fertilizers
D.
It is too expensive to buy
Ans:
It is grown without the use of chemicals & synthetic pesticides
Explanation :
There are at least two good arguments for eating organic: fewer pesticides and more nutrients. In the absence of pesticides and fertilizers, plants boost their production of the phytochernicals (vitamins and antioxidants) that strengthen their resistance to bugs and weeds. A major new study has found that organic foods contain higher levels of antioxidants and less harmful chemicals than conventionally farmed pro-duce.
[15] Nitrogen fixation is a process of -
A.
Assimilation of nitrate
B.
Utilisation of nitrogen gas
C.
Conversion of organic nitrogen to proteins
D.
Conversion of molecular nitrogen to ammonia
Ans:
Conversion of molecular nitrogen to ammonia
Explanation :
Nitrogen fixation is a process by which nitrogen in the Earth's atmosphere is converted into ammonia (NH3) or other molecules available to living organisms. Atmospheric nitrogen or molecular dinitrogen (N2) is relatively inert: it does not easily react with other chemicals to form new compounds. The fixation process frees nitrogen atoms from their triply bonded diatomic form, to be used by plants as nutrients. The conversion of organic nitrogen to proteins is achieved in Nitrogen cycle.
[16] What are soaps?
A.
Salts of silicates
B.
Ester of heavy fatty acids
C.
Sodium or potassium salts of heavier fatty acids
D.
Mixture of glycerol and alcohol
Ans:
Sodium or potassium salts of heavier fatty acids
Explanation :
0
[17] Electrolysis of an aqueous solution of copper sulphate using copper electrodes gives -
A.
Copper at eathode and oxygen at anode.
B.
Copper at anode and oxygen at cathode.
C.
Copper at cathode and anodes dissolve to give copper.
D.
Hydrogen at cathode and oxygen at anode.
Ans:
Copper at eathode and oxygen at anode.
Explanation :
Copper is deposited at the cathode and is dissolved at the anode. Consequently the concentration of copper ions in solution remains constant. This can be used as a method of purification of copper as only pure copper is deposited at the cathode
[18] Phosphorus is kept in water because –
A.
its ignition temperature is very high
B.
its ignition temperature is very low
C.
its critical temperature is high
D.
its critical temperature is low
Ans:
its ignition temperature is very low
Explanation :
The allotropic form of Phosphorus (white phosphorus) is less stable and therefore highly reactive because of angular strain in P4 molecule where the angles are only 600.
[19] The relation between bond length and bond energy is -
A.
Lower the bond energy, shorter the bond length
B.
They are not related
C.
Higher the bond energy, shorter the bond length
D.
Higher the bond energy, longer the bond length
Ans:
Higher the bond energy, shorter the bond length
Explanation :
Generally, the shorter the bond, the stronger the bond and the higher the dissociation energy. Bond energy is a measure of the strength in a chemical bond.
[20] In an atomic explosion enormous energy is released which is due to the -
A.
Conversions of neutrons into protons
B.
Conversion of chemical energy into nuclear energy
C.
Conversion of mechanical energy into nuclear energy
D.
Conversion of mass into energy
Ans:
Conversion of mass into energy
Explanation :
0
[21] Sea water is saltier than rain water because –
A.
Sea animals are salt producing
B.
The air around the sea is saltish
C.
Rivers wash away salts from earth and pour them into the sea
D.
Sea beds have salt producing mines
Ans:
Rivers wash away salts from earth and pour them into the sea
Explanation :
Seawater is salty because rainwater dissolves the salt minerals found in soil and rocks as it travels through rivers arid streams en route to the sea The rain that falls on the land contains some dissolved carbon dioxide from the surrounding air.
[22] Refrigerators keep food unspoiled because –
A.
at its low temperature, bacteria and moulds are inactive
B.
at its low temperature, the germs are killed
C.
at its low temperature, the germs are frozen
D.
it sterilizes the food
Ans:
at its low temperature, bacteria and moulds are inactive
Explanation :
Bacteria and moulds find conditions of low pH, moisture, or temperature and high salt or sugar unfavorable for their operation. This is the principle why refrigerators keep food unspoiled for a long time. Bacterial action is severely impaired at temperatures at or below 4 degree Celsius.
[23] Why is water not suitable for putting out a petrol fire?
A.
The oxygen content of water is isolated by petrol and thus it helps in burning
B.
Petrol is too inflammable to be extinguished by water
C.
The heat required for combustion of petrol is very low
D.
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Ans:
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Explanation :
Water is not effective on petrol fire because it has higher density than petrol as a result of which it sinks to the bottom, while petrol stays afloat and keeps burning. Petro-chemical fires are nearly always extinguished with chemical foam which forms a blanket over the flames and cuts off the oxygen supply.
[24] All isotopes of the same element have _.
A.
different atomic numbers and different atomic mass
B.
different atomic numbers and the same atomic mass
C.
the same atomic number but different atomic masses
D.
the same atomic number and the atomic mass
Ans:
the same atomic number but different atomic masses
Explanation :
Isotopes are forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei. So they have the same atomic number, but differ in relative atomic mass.
[25] Sodium vapour lamps glow with yellow colour. This is due to -
A.
sublimation of sodium to emit yellow colour
B.
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
C.
the low ionisation energy of sodium
D.
its ability to absorb all other colours except yellow
Ans:
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
Explanation :
Sodium Vapour Lamps glow with yellow colour due to the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum.
Explanation :
Acid rain is caused by emissions of sulfur dioxide (SO2) and nitrogen oxide (NO), which react with the water molecules in the atmosphere to produce acids. The SO2 and NOx react with water, oxygen and other chemicals to form sulfuric and nitric acids. The chemicals in acid rain can cause paint to peel, corrosion of steel structures and weathering of stone buildings.
[4] Thermal electricity is generated by using which of these?
A.
Coal only
B.
Coal and Natural Gas only
C.
Coal, Natural Gas and Petroleum
D.
None of these
Ans:
Coal, Natural Gas and Petroleum
Explanation :
A thermal power station is a power plant in which heat energy is converted to electric power. Thermal power is producing using fossil fuel such as coal, natural gas or petroleum.
[5] Synthetic detergents are made from –
A.
Sodium stearate
B.
Sodium salt of benzene sulphonic acid
C.
Sodium salt of benzene carboxylic acid
D.
Sodium palmitate
Ans:
Sodium salt of benzene sulphonic acid
Explanation :
Synthetic detergents are made from sodium salt of benezene sulphonic acid.
[6] The open "Sigrees” or coal stoves often require fanning to sustain burning because of -
A.
tendency of carbon dioxide to form a layer along with dust smoke
B.
lack of oxygen in the surroundings of sigrees
C.
accumulation of smoke and dust over the sigrees
D.
interrupted release of moisture from the material
Ans:
tendency of carbon dioxide to form a layer along with dust smoke
Explanation :
Burning coal requires oxygen to chemically react. The availability of oxygen is limited in the furnace by several factors such as the friction of the air against the coal. Blowing provides more oxygen to the flame and raises the temperature of the flame. Besides, it helps to prevent carbon dioxide from forming layer along with dust smoke so as to keep the supply of oxygen intact.
[7] Antacid tablets consist of –
A.
Hydroxides of sodium, magnesium and aluminium
B.
Hydroxides of magnesium and aluminium
C.
Hydroxides of sodium and aluminium
D.
Hydroxides of magnesium and sodium
Ans:
Hydroxides of magnesium and aluminium
Explanation :
An antacid is a base which neutralizes stomach acidity. The most common of these bases are hydroxides, carbonates, or bicarbonates such as Aluminum hydroxide, Calcium. carbonate, Magnesium carbonate, Magnesium hydroxide, and Sodium bicarbonate.
[8] Acid rain is caused by the pollution of environment by -
A.
carbon dioxide and nitrogen
B.
carbón monoxide and carbon dioxide
C.
ozone and carbon dioxide
D.
nitrous oxide and sulphur dioxide
Ans:
nitrous oxide and sulphur dioxide
Explanation :
[9] Synthetic detergents are prepared from –
A.
potassium salts of higher fatty-acids
B.
sodium salts of higher fat acids
C.
hydrocarbons of petroleum
D.
glycerides
Ans:
hydrocarbons of petroleum
Explanation :
Synthetic detergents are prepared from hydrocarbons of petroleum. They are sodium salts of long chain benzene sulphonic acids or sodium salts of long chain alkyl hydrogen sulphates. Calcium and magnesium salts of detergents are soluble in water. Therefore cleansing action of detergents remains unaffected in hard water.
[10] Metals have .
A.
High melting and boiling point
B.
Low melting and boiling point
C.
High melting and low boiling point
D.
Low melting and high boiling point
Ans:
High melting and boiling point
Explanation :
As metals are giant lattice structures, the number of electrostatic forces to be broken is extremely large, and so metals have high melting and boiling points. This means that the melting point and boiling point of metals are more similar to those for ionic compounds than for covalent substances.
[11] Soap helps in better cleaning of clothes because -
A.
Soap acts like catalyst
B.
It reduces the surface tension of solution
C.
It gives strength to solution
D.
It absorbs the dirt
Ans:
It reduces the surface tension of solution
Explanation :
Soaps are effective cleaners because they can dissolve and the oil and grease that holds dirt in place. They reduce the surface tension of the solution and enable it to wet things more uniformly. The surfactants in detergents improve water's ability to wet things, spread over surfaces, and seep into dirty clothes fibers. The surfactant molecules help water to get a hold of grease, break it up, and wash it away.
[12] Acid rain is caused by, the pollution of environment by -
A.
carbon dioxide and nitrogen
B.
carbon monoxide and carbon dioxide
C.
ozone and carbon dioxide
D.
nitrous oxide and sulphur dioxide
Ans:
carbon dioxide and nitrogen
Explanation :
0
[13] The enormous amount of energy released in an explosion of an atomic bomb is due to the -
A.
conversion of mass into energy
B.
conversion of chemical energy into heat energy
C.
conversion of mechnical energy into nuclear energy
D.
conversion of neutrons into protons
Ans:
conversion of neutrons into protons
Explanation :
The enormous amount of energy released in an explosion of an atomic bomb is due to the converson of neutrons into protons. When, a neutron strikes the nucleus of an atom of the isotopes uranium 235 or plutonium 239, it causes that nucleus to split into two fragmens, each of which is a nucleus with about half the protons and neutrons of the original nucleus.
[14] Organic food is supposed to be better for human consumption because –
A.
It is grown in glass house air tight environment
B.
It is grown without the use of chemicals & synthetic pesticides
C.
It depends on chemicals & fertilizers
D.
It is too expensive to buy
Ans:
It is grown without the use of chemicals & synthetic pesticides
Explanation :
There are at least two good arguments for eating organic: fewer pesticides and more nutrients. In the absence of pesticides and fertilizers, plants boost their production of the phytochernicals (vitamins and antioxidants) that strengthen their resistance to bugs and weeds. A major new study has found that organic foods contain higher levels of antioxidants and less harmful chemicals than conventionally farmed pro-duce.
[15] Nitrogen fixation is a process of -
A.
Assimilation of nitrate
B.
Utilisation of nitrogen gas
C.
Conversion of organic nitrogen to proteins
D.
Conversion of molecular nitrogen to ammonia
Ans:
Conversion of molecular nitrogen to ammonia
Explanation :
Nitrogen fixation is a process by which nitrogen in the Earth's atmosphere is converted into ammonia (NH3) or other molecules available to living organisms. Atmospheric nitrogen or molecular dinitrogen (N2) is relatively inert: it does not easily react with other chemicals to form new compounds. The fixation process frees nitrogen atoms from their triply bonded diatomic form, to be used by plants as nutrients. The conversion of organic nitrogen to proteins is achieved in Nitrogen cycle.
[16] What are soaps?
A.
Salts of silicates
B.
Ester of heavy fatty acids
C.
Sodium or potassium salts of heavier fatty acids
D.
Mixture of glycerol and alcohol
Ans:
Sodium or potassium salts of heavier fatty acids
Explanation :
0
[17] Electrolysis of an aqueous solution of copper sulphate using copper electrodes gives -
A.
Copper at eathode and oxygen at anode.
B.
Copper at anode and oxygen at cathode.
C.
Copper at cathode and anodes dissolve to give copper.
D.
Hydrogen at cathode and oxygen at anode.
Ans:
Copper at eathode and oxygen at anode.
Explanation :
Copper is deposited at the cathode and is dissolved at the anode. Consequently the concentration of copper ions in solution remains constant. This can be used as a method of purification of copper as only pure copper is deposited at the cathode
[18] Phosphorus is kept in water because –
A.
its ignition temperature is very high
B.
its ignition temperature is very low
C.
its critical temperature is high
D.
its critical temperature is low
Ans:
its ignition temperature is very low
Explanation :
The allotropic form of Phosphorus (white phosphorus) is less stable and therefore highly reactive because of angular strain in P4 molecule where the angles are only 600.
[19] The relation between bond length and bond energy is -
A.
Lower the bond energy, shorter the bond length
B.
They are not related
C.
Higher the bond energy, shorter the bond length
D.
Higher the bond energy, longer the bond length
Ans:
Higher the bond energy, shorter the bond length
Explanation :
Generally, the shorter the bond, the stronger the bond and the higher the dissociation energy. Bond energy is a measure of the strength in a chemical bond.
[20] In an atomic explosion enormous energy is released which is due to the -
A.
Conversions of neutrons into protons
B.
Conversion of chemical energy into nuclear energy
C.
Conversion of mechanical energy into nuclear energy
D.
Conversion of mass into energy
Ans:
Conversion of mass into energy
Explanation :
0
[21] Sea water is saltier than rain water because –
A.
Sea animals are salt producing
B.
The air around the sea is saltish
C.
Rivers wash away salts from earth and pour them into the sea
D.
Sea beds have salt producing mines
Ans:
Rivers wash away salts from earth and pour them into the sea
Explanation :
Seawater is salty because rainwater dissolves the salt minerals found in soil and rocks as it travels through rivers arid streams en route to the sea The rain that falls on the land contains some dissolved carbon dioxide from the surrounding air.
[22] Refrigerators keep food unspoiled because –
A.
at its low temperature, bacteria and moulds are inactive
B.
at its low temperature, the germs are killed
C.
at its low temperature, the germs are frozen
D.
it sterilizes the food
Ans:
at its low temperature, bacteria and moulds are inactive
Explanation :
Bacteria and moulds find conditions of low pH, moisture, or temperature and high salt or sugar unfavorable for their operation. This is the principle why refrigerators keep food unspoiled for a long time. Bacterial action is severely impaired at temperatures at or below 4 degree Celsius.
[23] Why is water not suitable for putting out a petrol fire?
A.
The oxygen content of water is isolated by petrol and thus it helps in burning
B.
Petrol is too inflammable to be extinguished by water
C.
The heat required for combustion of petrol is very low
D.
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Ans:
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Explanation :
Water is not effective on petrol fire because it has higher density than petrol as a result of which it sinks to the bottom, while petrol stays afloat and keeps burning. Petro-chemical fires are nearly always extinguished with chemical foam which forms a blanket over the flames and cuts off the oxygen supply.
[24] All isotopes of the same element have _.
A.
different atomic numbers and different atomic mass
B.
different atomic numbers and the same atomic mass
C.
the same atomic number but different atomic masses
D.
the same atomic number and the atomic mass
Ans:
the same atomic number but different atomic masses
Explanation :
Isotopes are forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei. So they have the same atomic number, but differ in relative atomic mass.
[25] Sodium vapour lamps glow with yellow colour. This is due to -
A.
sublimation of sodium to emit yellow colour
B.
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
C.
the low ionisation energy of sodium
D.
its ability to absorb all other colours except yellow
Ans:
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
Explanation :
Sodium Vapour Lamps glow with yellow colour due to the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum.
Explanation :
Synthetic detergents are made from sodium salt of benezene sulphonic acid.
[6] The open "Sigrees” or coal stoves often require fanning to sustain burning because of -
A.
tendency of carbon dioxide to form a layer along with dust smoke
B.
lack of oxygen in the surroundings of sigrees
C.
accumulation of smoke and dust over the sigrees
D.
interrupted release of moisture from the material
Ans:
tendency of carbon dioxide to form a layer along with dust smoke
Explanation :
Burning coal requires oxygen to chemically react. The availability of oxygen is limited in the furnace by several factors such as the friction of the air against the coal. Blowing provides more oxygen to the flame and raises the temperature of the flame. Besides, it helps to prevent carbon dioxide from forming layer along with dust smoke so as to keep the supply of oxygen intact.
[7] Antacid tablets consist of –
A.
Hydroxides of sodium, magnesium and aluminium
B.
Hydroxides of magnesium and aluminium
C.
Hydroxides of sodium and aluminium
D.
Hydroxides of magnesium and sodium
Ans:
Hydroxides of magnesium and aluminium
Explanation :
An antacid is a base which neutralizes stomach acidity. The most common of these bases are hydroxides, carbonates, or bicarbonates such as Aluminum hydroxide, Calcium. carbonate, Magnesium carbonate, Magnesium hydroxide, and Sodium bicarbonate.
[8] Acid rain is caused by the pollution of environment by -
A.
carbon dioxide and nitrogen
B.
carbón monoxide and carbon dioxide
C.
ozone and carbon dioxide
D.
nitrous oxide and sulphur dioxide
Ans:
nitrous oxide and sulphur dioxide
Explanation :
[9] Synthetic detergents are prepared from –
A.
potassium salts of higher fatty-acids
B.
sodium salts of higher fat acids
C.
hydrocarbons of petroleum
D.
glycerides
Ans:
hydrocarbons of petroleum
Explanation :
Synthetic detergents are prepared from hydrocarbons of petroleum. They are sodium salts of long chain benzene sulphonic acids or sodium salts of long chain alkyl hydrogen sulphates. Calcium and magnesium salts of detergents are soluble in water. Therefore cleansing action of detergents remains unaffected in hard water.
[10] Metals have .
A.
High melting and boiling point
B.
Low melting and boiling point
C.
High melting and low boiling point
D.
Low melting and high boiling point
Ans:
High melting and boiling point
Explanation :
As metals are giant lattice structures, the number of electrostatic forces to be broken is extremely large, and so metals have high melting and boiling points. This means that the melting point and boiling point of metals are more similar to those for ionic compounds than for covalent substances.
[11] Soap helps in better cleaning of clothes because -
A.
Soap acts like catalyst
B.
It reduces the surface tension of solution
C.
It gives strength to solution
D.
It absorbs the dirt
Ans:
It reduces the surface tension of solution
Explanation :
Soaps are effective cleaners because they can dissolve and the oil and grease that holds dirt in place. They reduce the surface tension of the solution and enable it to wet things more uniformly. The surfactants in detergents improve water's ability to wet things, spread over surfaces, and seep into dirty clothes fibers. The surfactant molecules help water to get a hold of grease, break it up, and wash it away.
[12] Acid rain is caused by, the pollution of environment by -
A.
carbon dioxide and nitrogen
B.
carbon monoxide and carbon dioxide
C.
ozone and carbon dioxide
D.
nitrous oxide and sulphur dioxide
Ans:
carbon dioxide and nitrogen
Explanation :
0
[13] The enormous amount of energy released in an explosion of an atomic bomb is due to the -
A.
conversion of mass into energy
B.
conversion of chemical energy into heat energy
C.
conversion of mechnical energy into nuclear energy
D.
conversion of neutrons into protons
Ans:
conversion of neutrons into protons
Explanation :
The enormous amount of energy released in an explosion of an atomic bomb is due to the converson of neutrons into protons. When, a neutron strikes the nucleus of an atom of the isotopes uranium 235 or plutonium 239, it causes that nucleus to split into two fragmens, each of which is a nucleus with about half the protons and neutrons of the original nucleus.
[14] Organic food is supposed to be better for human consumption because –
A.
It is grown in glass house air tight environment
B.
It is grown without the use of chemicals & synthetic pesticides
C.
It depends on chemicals & fertilizers
D.
It is too expensive to buy
Ans:
It is grown without the use of chemicals & synthetic pesticides
Explanation :
There are at least two good arguments for eating organic: fewer pesticides and more nutrients. In the absence of pesticides and fertilizers, plants boost their production of the phytochernicals (vitamins and antioxidants) that strengthen their resistance to bugs and weeds. A major new study has found that organic foods contain higher levels of antioxidants and less harmful chemicals than conventionally farmed pro-duce.
[15] Nitrogen fixation is a process of -
A.
Assimilation of nitrate
B.
Utilisation of nitrogen gas
C.
Conversion of organic nitrogen to proteins
D.
Conversion of molecular nitrogen to ammonia
Ans:
Conversion of molecular nitrogen to ammonia
Explanation :
Nitrogen fixation is a process by which nitrogen in the Earth's atmosphere is converted into ammonia (NH3) or other molecules available to living organisms. Atmospheric nitrogen or molecular dinitrogen (N2) is relatively inert: it does not easily react with other chemicals to form new compounds. The fixation process frees nitrogen atoms from their triply bonded diatomic form, to be used by plants as nutrients. The conversion of organic nitrogen to proteins is achieved in Nitrogen cycle.
[16] What are soaps?
A.
Salts of silicates
B.
Ester of heavy fatty acids
C.
Sodium or potassium salts of heavier fatty acids
D.
Mixture of glycerol and alcohol
Ans:
Sodium or potassium salts of heavier fatty acids
Explanation :
0
[17] Electrolysis of an aqueous solution of copper sulphate using copper electrodes gives -
A.
Copper at eathode and oxygen at anode.
B.
Copper at anode and oxygen at cathode.
C.
Copper at cathode and anodes dissolve to give copper.
D.
Hydrogen at cathode and oxygen at anode.
Ans:
Copper at eathode and oxygen at anode.
Explanation :
Copper is deposited at the cathode and is dissolved at the anode. Consequently the concentration of copper ions in solution remains constant. This can be used as a method of purification of copper as only pure copper is deposited at the cathode
[18] Phosphorus is kept in water because –
A.
its ignition temperature is very high
B.
its ignition temperature is very low
C.
its critical temperature is high
D.
its critical temperature is low
Ans:
its ignition temperature is very low
Explanation :
The allotropic form of Phosphorus (white phosphorus) is less stable and therefore highly reactive because of angular strain in P4 molecule where the angles are only 600.
[19] The relation between bond length and bond energy is -
A.
Lower the bond energy, shorter the bond length
B.
They are not related
C.
Higher the bond energy, shorter the bond length
D.
Higher the bond energy, longer the bond length
Ans:
Higher the bond energy, shorter the bond length
Explanation :
Generally, the shorter the bond, the stronger the bond and the higher the dissociation energy. Bond energy is a measure of the strength in a chemical bond.
[20] In an atomic explosion enormous energy is released which is due to the -
A.
Conversions of neutrons into protons
B.
Conversion of chemical energy into nuclear energy
C.
Conversion of mechanical energy into nuclear energy
D.
Conversion of mass into energy
Ans:
Conversion of mass into energy
Explanation :
0
[21] Sea water is saltier than rain water because –
A.
Sea animals are salt producing
B.
The air around the sea is saltish
C.
Rivers wash away salts from earth and pour them into the sea
D.
Sea beds have salt producing mines
Ans:
Rivers wash away salts from earth and pour them into the sea
Explanation :
Seawater is salty because rainwater dissolves the salt minerals found in soil and rocks as it travels through rivers arid streams en route to the sea The rain that falls on the land contains some dissolved carbon dioxide from the surrounding air.
[22] Refrigerators keep food unspoiled because –
A.
at its low temperature, bacteria and moulds are inactive
B.
at its low temperature, the germs are killed
C.
at its low temperature, the germs are frozen
D.
it sterilizes the food
Ans:
at its low temperature, bacteria and moulds are inactive
Explanation :
Bacteria and moulds find conditions of low pH, moisture, or temperature and high salt or sugar unfavorable for their operation. This is the principle why refrigerators keep food unspoiled for a long time. Bacterial action is severely impaired at temperatures at or below 4 degree Celsius.
[23] Why is water not suitable for putting out a petrol fire?
A.
The oxygen content of water is isolated by petrol and thus it helps in burning
B.
Petrol is too inflammable to be extinguished by water
C.
The heat required for combustion of petrol is very low
D.
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Ans:
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Explanation :
Water is not effective on petrol fire because it has higher density than petrol as a result of which it sinks to the bottom, while petrol stays afloat and keeps burning. Petro-chemical fires are nearly always extinguished with chemical foam which forms a blanket over the flames and cuts off the oxygen supply.
[24] All isotopes of the same element have _.
A.
different atomic numbers and different atomic mass
B.
different atomic numbers and the same atomic mass
C.
the same atomic number but different atomic masses
D.
the same atomic number and the atomic mass
Ans:
the same atomic number but different atomic masses
Explanation :
Isotopes are forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei. So they have the same atomic number, but differ in relative atomic mass.
[25] Sodium vapour lamps glow with yellow colour. This is due to -
A.
sublimation of sodium to emit yellow colour
B.
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
C.
the low ionisation energy of sodium
D.
its ability to absorb all other colours except yellow
Ans:
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
Explanation :
Sodium Vapour Lamps glow with yellow colour due to the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum.
Explanation :
An antacid is a base which neutralizes stomach acidity. The most common of these bases are hydroxides, carbonates, or bicarbonates such as Aluminum hydroxide, Calcium. carbonate, Magnesium carbonate, Magnesium hydroxide, and Sodium bicarbonate.
[8] Acid rain is caused by the pollution of environment by -
A.
carbon dioxide and nitrogen
B.
carbón monoxide and carbon dioxide
C.
ozone and carbon dioxide
D.
nitrous oxide and sulphur dioxide
Ans:
nitrous oxide and sulphur dioxide
Explanation :
[9] Synthetic detergents are prepared from –
A.
potassium salts of higher fatty-acids
B.
sodium salts of higher fat acids
C.
hydrocarbons of petroleum
D.
glycerides
Ans:
hydrocarbons of petroleum
Explanation :
Synthetic detergents are prepared from hydrocarbons of petroleum. They are sodium salts of long chain benzene sulphonic acids or sodium salts of long chain alkyl hydrogen sulphates. Calcium and magnesium salts of detergents are soluble in water. Therefore cleansing action of detergents remains unaffected in hard water.
[10] Metals have .
A.
High melting and boiling point
B.
Low melting and boiling point
C.
High melting and low boiling point
D.
Low melting and high boiling point
Ans:
High melting and boiling point
Explanation :
As metals are giant lattice structures, the number of electrostatic forces to be broken is extremely large, and so metals have high melting and boiling points. This means that the melting point and boiling point of metals are more similar to those for ionic compounds than for covalent substances.
[11] Soap helps in better cleaning of clothes because -
A.
Soap acts like catalyst
B.
It reduces the surface tension of solution
C.
It gives strength to solution
D.
It absorbs the dirt
Ans:
It reduces the surface tension of solution
Explanation :
Soaps are effective cleaners because they can dissolve and the oil and grease that holds dirt in place. They reduce the surface tension of the solution and enable it to wet things more uniformly. The surfactants in detergents improve water's ability to wet things, spread over surfaces, and seep into dirty clothes fibers. The surfactant molecules help water to get a hold of grease, break it up, and wash it away.
[12] Acid rain is caused by, the pollution of environment by -
A.
carbon dioxide and nitrogen
B.
carbon monoxide and carbon dioxide
C.
ozone and carbon dioxide
D.
nitrous oxide and sulphur dioxide
Ans:
carbon dioxide and nitrogen
Explanation :
0
[13] The enormous amount of energy released in an explosion of an atomic bomb is due to the -
A.
conversion of mass into energy
B.
conversion of chemical energy into heat energy
C.
conversion of mechnical energy into nuclear energy
D.
conversion of neutrons into protons
Ans:
conversion of neutrons into protons
Explanation :
The enormous amount of energy released in an explosion of an atomic bomb is due to the converson of neutrons into protons. When, a neutron strikes the nucleus of an atom of the isotopes uranium 235 or plutonium 239, it causes that nucleus to split into two fragmens, each of which is a nucleus with about half the protons and neutrons of the original nucleus.
[14] Organic food is supposed to be better for human consumption because –
A.
It is grown in glass house air tight environment
B.
It is grown without the use of chemicals & synthetic pesticides
C.
It depends on chemicals & fertilizers
D.
It is too expensive to buy
Ans:
It is grown without the use of chemicals & synthetic pesticides
Explanation :
There are at least two good arguments for eating organic: fewer pesticides and more nutrients. In the absence of pesticides and fertilizers, plants boost their production of the phytochernicals (vitamins and antioxidants) that strengthen their resistance to bugs and weeds. A major new study has found that organic foods contain higher levels of antioxidants and less harmful chemicals than conventionally farmed pro-duce.
[15] Nitrogen fixation is a process of -
A.
Assimilation of nitrate
B.
Utilisation of nitrogen gas
C.
Conversion of organic nitrogen to proteins
D.
Conversion of molecular nitrogen to ammonia
Ans:
Conversion of molecular nitrogen to ammonia
Explanation :
Nitrogen fixation is a process by which nitrogen in the Earth's atmosphere is converted into ammonia (NH3) or other molecules available to living organisms. Atmospheric nitrogen or molecular dinitrogen (N2) is relatively inert: it does not easily react with other chemicals to form new compounds. The fixation process frees nitrogen atoms from their triply bonded diatomic form, to be used by plants as nutrients. The conversion of organic nitrogen to proteins is achieved in Nitrogen cycle.
[16] What are soaps?
A.
Salts of silicates
B.
Ester of heavy fatty acids
C.
Sodium or potassium salts of heavier fatty acids
D.
Mixture of glycerol and alcohol
Ans:
Sodium or potassium salts of heavier fatty acids
Explanation :
0
[17] Electrolysis of an aqueous solution of copper sulphate using copper electrodes gives -
A.
Copper at eathode and oxygen at anode.
B.
Copper at anode and oxygen at cathode.
C.
Copper at cathode and anodes dissolve to give copper.
D.
Hydrogen at cathode and oxygen at anode.
Ans:
Copper at eathode and oxygen at anode.
Explanation :
Copper is deposited at the cathode and is dissolved at the anode. Consequently the concentration of copper ions in solution remains constant. This can be used as a method of purification of copper as only pure copper is deposited at the cathode
[18] Phosphorus is kept in water because –
A.
its ignition temperature is very high
B.
its ignition temperature is very low
C.
its critical temperature is high
D.
its critical temperature is low
Ans:
its ignition temperature is very low
Explanation :
The allotropic form of Phosphorus (white phosphorus) is less stable and therefore highly reactive because of angular strain in P4 molecule where the angles are only 600.
[19] The relation between bond length and bond energy is -
A.
Lower the bond energy, shorter the bond length
B.
They are not related
C.
Higher the bond energy, shorter the bond length
D.
Higher the bond energy, longer the bond length
Ans:
Higher the bond energy, shorter the bond length
Explanation :
Generally, the shorter the bond, the stronger the bond and the higher the dissociation energy. Bond energy is a measure of the strength in a chemical bond.
[20] In an atomic explosion enormous energy is released which is due to the -
A.
Conversions of neutrons into protons
B.
Conversion of chemical energy into nuclear energy
C.
Conversion of mechanical energy into nuclear energy
D.
Conversion of mass into energy
Ans:
Conversion of mass into energy
Explanation :
0
[21] Sea water is saltier than rain water because –
A.
Sea animals are salt producing
B.
The air around the sea is saltish
C.
Rivers wash away salts from earth and pour them into the sea
D.
Sea beds have salt producing mines
Ans:
Rivers wash away salts from earth and pour them into the sea
Explanation :
Seawater is salty because rainwater dissolves the salt minerals found in soil and rocks as it travels through rivers arid streams en route to the sea The rain that falls on the land contains some dissolved carbon dioxide from the surrounding air.
[22] Refrigerators keep food unspoiled because –
A.
at its low temperature, bacteria and moulds are inactive
B.
at its low temperature, the germs are killed
C.
at its low temperature, the germs are frozen
D.
it sterilizes the food
Ans:
at its low temperature, bacteria and moulds are inactive
Explanation :
Bacteria and moulds find conditions of low pH, moisture, or temperature and high salt or sugar unfavorable for their operation. This is the principle why refrigerators keep food unspoiled for a long time. Bacterial action is severely impaired at temperatures at or below 4 degree Celsius.
[23] Why is water not suitable for putting out a petrol fire?
A.
The oxygen content of water is isolated by petrol and thus it helps in burning
B.
Petrol is too inflammable to be extinguished by water
C.
The heat required for combustion of petrol is very low
D.
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Ans:
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Explanation :
Water is not effective on petrol fire because it has higher density than petrol as a result of which it sinks to the bottom, while petrol stays afloat and keeps burning. Petro-chemical fires are nearly always extinguished with chemical foam which forms a blanket over the flames and cuts off the oxygen supply.
[24] All isotopes of the same element have _.
A.
different atomic numbers and different atomic mass
B.
different atomic numbers and the same atomic mass
C.
the same atomic number but different atomic masses
D.
the same atomic number and the atomic mass
Ans:
the same atomic number but different atomic masses
Explanation :
Isotopes are forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei. So they have the same atomic number, but differ in relative atomic mass.
[25] Sodium vapour lamps glow with yellow colour. This is due to -
A.
sublimation of sodium to emit yellow colour
B.
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
C.
the low ionisation energy of sodium
D.
its ability to absorb all other colours except yellow
Ans:
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
Explanation :
Sodium Vapour Lamps glow with yellow colour due to the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum.
Explanation :
Synthetic detergents are prepared from hydrocarbons of petroleum. They are sodium salts of long chain benzene sulphonic acids or sodium salts of long chain alkyl hydrogen sulphates. Calcium and magnesium salts of detergents are soluble in water. Therefore cleansing action of detergents remains unaffected in hard water.
[10] Metals have .
A.
High melting and boiling point
B.
Low melting and boiling point
C.
High melting and low boiling point
D.
Low melting and high boiling point
Ans:
High melting and boiling point
Explanation :
As metals are giant lattice structures, the number of electrostatic forces to be broken is extremely large, and so metals have high melting and boiling points. This means that the melting point and boiling point of metals are more similar to those for ionic compounds than for covalent substances.
[11] Soap helps in better cleaning of clothes because -
A.
Soap acts like catalyst
B.
It reduces the surface tension of solution
C.
It gives strength to solution
D.
It absorbs the dirt
Ans:
It reduces the surface tension of solution
Explanation :
Soaps are effective cleaners because they can dissolve and the oil and grease that holds dirt in place. They reduce the surface tension of the solution and enable it to wet things more uniformly. The surfactants in detergents improve water's ability to wet things, spread over surfaces, and seep into dirty clothes fibers. The surfactant molecules help water to get a hold of grease, break it up, and wash it away.
[12] Acid rain is caused by, the pollution of environment by -
A.
carbon dioxide and nitrogen
B.
carbon monoxide and carbon dioxide
C.
ozone and carbon dioxide
D.
nitrous oxide and sulphur dioxide
Ans:
carbon dioxide and nitrogen
Explanation :
0
[13] The enormous amount of energy released in an explosion of an atomic bomb is due to the -
A.
conversion of mass into energy
B.
conversion of chemical energy into heat energy
C.
conversion of mechnical energy into nuclear energy
D.
conversion of neutrons into protons
Ans:
conversion of neutrons into protons
Explanation :
The enormous amount of energy released in an explosion of an atomic bomb is due to the converson of neutrons into protons. When, a neutron strikes the nucleus of an atom of the isotopes uranium 235 or plutonium 239, it causes that nucleus to split into two fragmens, each of which is a nucleus with about half the protons and neutrons of the original nucleus.
[14] Organic food is supposed to be better for human consumption because –
A.
It is grown in glass house air tight environment
B.
It is grown without the use of chemicals & synthetic pesticides
C.
It depends on chemicals & fertilizers
D.
It is too expensive to buy
Ans:
It is grown without the use of chemicals & synthetic pesticides
Explanation :
There are at least two good arguments for eating organic: fewer pesticides and more nutrients. In the absence of pesticides and fertilizers, plants boost their production of the phytochernicals (vitamins and antioxidants) that strengthen their resistance to bugs and weeds. A major new study has found that organic foods contain higher levels of antioxidants and less harmful chemicals than conventionally farmed pro-duce.
[15] Nitrogen fixation is a process of -
A.
Assimilation of nitrate
B.
Utilisation of nitrogen gas
C.
Conversion of organic nitrogen to proteins
D.
Conversion of molecular nitrogen to ammonia
Ans:
Conversion of molecular nitrogen to ammonia
Explanation :
Nitrogen fixation is a process by which nitrogen in the Earth's atmosphere is converted into ammonia (NH3) or other molecules available to living organisms. Atmospheric nitrogen or molecular dinitrogen (N2) is relatively inert: it does not easily react with other chemicals to form new compounds. The fixation process frees nitrogen atoms from their triply bonded diatomic form, to be used by plants as nutrients. The conversion of organic nitrogen to proteins is achieved in Nitrogen cycle.
[16] What are soaps?
A.
Salts of silicates
B.
Ester of heavy fatty acids
C.
Sodium or potassium salts of heavier fatty acids
D.
Mixture of glycerol and alcohol
Ans:
Sodium or potassium salts of heavier fatty acids
Explanation :
0
[17] Electrolysis of an aqueous solution of copper sulphate using copper electrodes gives -
A.
Copper at eathode and oxygen at anode.
B.
Copper at anode and oxygen at cathode.
C.
Copper at cathode and anodes dissolve to give copper.
D.
Hydrogen at cathode and oxygen at anode.
Ans:
Copper at eathode and oxygen at anode.
Explanation :
Copper is deposited at the cathode and is dissolved at the anode. Consequently the concentration of copper ions in solution remains constant. This can be used as a method of purification of copper as only pure copper is deposited at the cathode
[18] Phosphorus is kept in water because –
A.
its ignition temperature is very high
B.
its ignition temperature is very low
C.
its critical temperature is high
D.
its critical temperature is low
Ans:
its ignition temperature is very low
Explanation :
The allotropic form of Phosphorus (white phosphorus) is less stable and therefore highly reactive because of angular strain in P4 molecule where the angles are only 600.
[19] The relation between bond length and bond energy is -
A.
Lower the bond energy, shorter the bond length
B.
They are not related
C.
Higher the bond energy, shorter the bond length
D.
Higher the bond energy, longer the bond length
Ans:
Higher the bond energy, shorter the bond length
Explanation :
Generally, the shorter the bond, the stronger the bond and the higher the dissociation energy. Bond energy is a measure of the strength in a chemical bond.
[20] In an atomic explosion enormous energy is released which is due to the -
A.
Conversions of neutrons into protons
B.
Conversion of chemical energy into nuclear energy
C.
Conversion of mechanical energy into nuclear energy
D.
Conversion of mass into energy
Ans:
Conversion of mass into energy
Explanation :
0
[21] Sea water is saltier than rain water because –
A.
Sea animals are salt producing
B.
The air around the sea is saltish
C.
Rivers wash away salts from earth and pour them into the sea
D.
Sea beds have salt producing mines
Ans:
Rivers wash away salts from earth and pour them into the sea
Explanation :
Seawater is salty because rainwater dissolves the salt minerals found in soil and rocks as it travels through rivers arid streams en route to the sea The rain that falls on the land contains some dissolved carbon dioxide from the surrounding air.
[22] Refrigerators keep food unspoiled because –
A.
at its low temperature, bacteria and moulds are inactive
B.
at its low temperature, the germs are killed
C.
at its low temperature, the germs are frozen
D.
it sterilizes the food
Ans:
at its low temperature, bacteria and moulds are inactive
Explanation :
Bacteria and moulds find conditions of low pH, moisture, or temperature and high salt or sugar unfavorable for their operation. This is the principle why refrigerators keep food unspoiled for a long time. Bacterial action is severely impaired at temperatures at or below 4 degree Celsius.
[23] Why is water not suitable for putting out a petrol fire?
A.
The oxygen content of water is isolated by petrol and thus it helps in burning
B.
Petrol is too inflammable to be extinguished by water
C.
The heat required for combustion of petrol is very low
D.
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Ans:
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Explanation :
Water is not effective on petrol fire because it has higher density than petrol as a result of which it sinks to the bottom, while petrol stays afloat and keeps burning. Petro-chemical fires are nearly always extinguished with chemical foam which forms a blanket over the flames and cuts off the oxygen supply.
[24] All isotopes of the same element have _.
A.
different atomic numbers and different atomic mass
B.
different atomic numbers and the same atomic mass
C.
the same atomic number but different atomic masses
D.
the same atomic number and the atomic mass
Ans:
the same atomic number but different atomic masses
Explanation :
Isotopes are forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei. So they have the same atomic number, but differ in relative atomic mass.
[25] Sodium vapour lamps glow with yellow colour. This is due to -
A.
sublimation of sodium to emit yellow colour
B.
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
C.
the low ionisation energy of sodium
D.
its ability to absorb all other colours except yellow
Ans:
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
Explanation :
Sodium Vapour Lamps glow with yellow colour due to the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum.
Explanation :
Soaps are effective cleaners because they can dissolve and the oil and grease that holds dirt in place. They reduce the surface tension of the solution and enable it to wet things more uniformly. The surfactants in detergents improve water's ability to wet things, spread over surfaces, and seep into dirty clothes fibers. The surfactant molecules help water to get a hold of grease, break it up, and wash it away.
[12] Acid rain is caused by, the pollution of environment by -
A.
carbon dioxide and nitrogen
B.
carbon monoxide and carbon dioxide
C.
ozone and carbon dioxide
D.
nitrous oxide and sulphur dioxide
Ans:
carbon dioxide and nitrogen
Explanation :
0
[13] The enormous amount of energy released in an explosion of an atomic bomb is due to the -
A.
conversion of mass into energy
B.
conversion of chemical energy into heat energy
C.
conversion of mechnical energy into nuclear energy
D.
conversion of neutrons into protons
Ans:
conversion of neutrons into protons
Explanation :
The enormous amount of energy released in an explosion of an atomic bomb is due to the converson of neutrons into protons. When, a neutron strikes the nucleus of an atom of the isotopes uranium 235 or plutonium 239, it causes that nucleus to split into two fragmens, each of which is a nucleus with about half the protons and neutrons of the original nucleus.
[14] Organic food is supposed to be better for human consumption because –
A.
It is grown in glass house air tight environment
B.
It is grown without the use of chemicals & synthetic pesticides
C.
It depends on chemicals & fertilizers
D.
It is too expensive to buy
Ans:
It is grown without the use of chemicals & synthetic pesticides
Explanation :
There are at least two good arguments for eating organic: fewer pesticides and more nutrients. In the absence of pesticides and fertilizers, plants boost their production of the phytochernicals (vitamins and antioxidants) that strengthen their resistance to bugs and weeds. A major new study has found that organic foods contain higher levels of antioxidants and less harmful chemicals than conventionally farmed pro-duce.
[15] Nitrogen fixation is a process of -
A.
Assimilation of nitrate
B.
Utilisation of nitrogen gas
C.
Conversion of organic nitrogen to proteins
D.
Conversion of molecular nitrogen to ammonia
Ans:
Conversion of molecular nitrogen to ammonia
Explanation :
Nitrogen fixation is a process by which nitrogen in the Earth's atmosphere is converted into ammonia (NH3) or other molecules available to living organisms. Atmospheric nitrogen or molecular dinitrogen (N2) is relatively inert: it does not easily react with other chemicals to form new compounds. The fixation process frees nitrogen atoms from their triply bonded diatomic form, to be used by plants as nutrients. The conversion of organic nitrogen to proteins is achieved in Nitrogen cycle.
[16] What are soaps?
A.
Salts of silicates
B.
Ester of heavy fatty acids
C.
Sodium or potassium salts of heavier fatty acids
D.
Mixture of glycerol and alcohol
Ans:
Sodium or potassium salts of heavier fatty acids
Explanation :
0
[17] Electrolysis of an aqueous solution of copper sulphate using copper electrodes gives -
A.
Copper at eathode and oxygen at anode.
B.
Copper at anode and oxygen at cathode.
C.
Copper at cathode and anodes dissolve to give copper.
D.
Hydrogen at cathode and oxygen at anode.
Ans:
Copper at eathode and oxygen at anode.
Explanation :
Copper is deposited at the cathode and is dissolved at the anode. Consequently the concentration of copper ions in solution remains constant. This can be used as a method of purification of copper as only pure copper is deposited at the cathode
[18] Phosphorus is kept in water because –
A.
its ignition temperature is very high
B.
its ignition temperature is very low
C.
its critical temperature is high
D.
its critical temperature is low
Ans:
its ignition temperature is very low
Explanation :
The allotropic form of Phosphorus (white phosphorus) is less stable and therefore highly reactive because of angular strain in P4 molecule where the angles are only 600.
[19] The relation between bond length and bond energy is -
A.
Lower the bond energy, shorter the bond length
B.
They are not related
C.
Higher the bond energy, shorter the bond length
D.
Higher the bond energy, longer the bond length
Ans:
Higher the bond energy, shorter the bond length
Explanation :
Generally, the shorter the bond, the stronger the bond and the higher the dissociation energy. Bond energy is a measure of the strength in a chemical bond.
[20] In an atomic explosion enormous energy is released which is due to the -
A.
Conversions of neutrons into protons
B.
Conversion of chemical energy into nuclear energy
C.
Conversion of mechanical energy into nuclear energy
D.
Conversion of mass into energy
Ans:
Conversion of mass into energy
Explanation :
0
[21] Sea water is saltier than rain water because –
A.
Sea animals are salt producing
B.
The air around the sea is saltish
C.
Rivers wash away salts from earth and pour them into the sea
D.
Sea beds have salt producing mines
Ans:
Rivers wash away salts from earth and pour them into the sea
Explanation :
Seawater is salty because rainwater dissolves the salt minerals found in soil and rocks as it travels through rivers arid streams en route to the sea The rain that falls on the land contains some dissolved carbon dioxide from the surrounding air.
[22] Refrigerators keep food unspoiled because –
A.
at its low temperature, bacteria and moulds are inactive
B.
at its low temperature, the germs are killed
C.
at its low temperature, the germs are frozen
D.
it sterilizes the food
Ans:
at its low temperature, bacteria and moulds are inactive
Explanation :
Bacteria and moulds find conditions of low pH, moisture, or temperature and high salt or sugar unfavorable for their operation. This is the principle why refrigerators keep food unspoiled for a long time. Bacterial action is severely impaired at temperatures at or below 4 degree Celsius.
[23] Why is water not suitable for putting out a petrol fire?
A.
The oxygen content of water is isolated by petrol and thus it helps in burning
B.
Petrol is too inflammable to be extinguished by water
C.
The heat required for combustion of petrol is very low
D.
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Ans:
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Explanation :
Water is not effective on petrol fire because it has higher density than petrol as a result of which it sinks to the bottom, while petrol stays afloat and keeps burning. Petro-chemical fires are nearly always extinguished with chemical foam which forms a blanket over the flames and cuts off the oxygen supply.
[24] All isotopes of the same element have _.
A.
different atomic numbers and different atomic mass
B.
different atomic numbers and the same atomic mass
C.
the same atomic number but different atomic masses
D.
the same atomic number and the atomic mass
Ans:
the same atomic number but different atomic masses
Explanation :
Isotopes are forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei. So they have the same atomic number, but differ in relative atomic mass.
[25] Sodium vapour lamps glow with yellow colour. This is due to -
A.
sublimation of sodium to emit yellow colour
B.
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
C.
the low ionisation energy of sodium
D.
its ability to absorb all other colours except yellow
Ans:
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
Explanation :
Sodium Vapour Lamps glow with yellow colour due to the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum.
Explanation :
The enormous amount of energy released in an explosion of an atomic bomb is due to the converson of neutrons into protons. When, a neutron strikes the nucleus of an atom of the isotopes uranium 235 or plutonium 239, it causes that nucleus to split into two fragmens, each of which is a nucleus with about half the protons and neutrons of the original nucleus.
[14] Organic food is supposed to be better for human consumption because –
A.
It is grown in glass house air tight environment
B.
It is grown without the use of chemicals & synthetic pesticides
C.
It depends on chemicals & fertilizers
D.
It is too expensive to buy
Ans:
It is grown without the use of chemicals & synthetic pesticides
Explanation :
There are at least two good arguments for eating organic: fewer pesticides and more nutrients. In the absence of pesticides and fertilizers, plants boost their production of the phytochernicals (vitamins and antioxidants) that strengthen their resistance to bugs and weeds. A major new study has found that organic foods contain higher levels of antioxidants and less harmful chemicals than conventionally farmed pro-duce.
[15] Nitrogen fixation is a process of -
A.
Assimilation of nitrate
B.
Utilisation of nitrogen gas
C.
Conversion of organic nitrogen to proteins
D.
Conversion of molecular nitrogen to ammonia
Ans:
Conversion of molecular nitrogen to ammonia
Explanation :
Nitrogen fixation is a process by which nitrogen in the Earth's atmosphere is converted into ammonia (NH3) or other molecules available to living organisms. Atmospheric nitrogen or molecular dinitrogen (N2) is relatively inert: it does not easily react with other chemicals to form new compounds. The fixation process frees nitrogen atoms from their triply bonded diatomic form, to be used by plants as nutrients. The conversion of organic nitrogen to proteins is achieved in Nitrogen cycle.
[16] What are soaps?
A.
Salts of silicates
B.
Ester of heavy fatty acids
C.
Sodium or potassium salts of heavier fatty acids
D.
Mixture of glycerol and alcohol
Ans:
Sodium or potassium salts of heavier fatty acids
Explanation :
0
[17] Electrolysis of an aqueous solution of copper sulphate using copper electrodes gives -
A.
Copper at eathode and oxygen at anode.
B.
Copper at anode and oxygen at cathode.
C.
Copper at cathode and anodes dissolve to give copper.
D.
Hydrogen at cathode and oxygen at anode.
Ans:
Copper at eathode and oxygen at anode.
Explanation :
Copper is deposited at the cathode and is dissolved at the anode. Consequently the concentration of copper ions in solution remains constant. This can be used as a method of purification of copper as only pure copper is deposited at the cathode
[18] Phosphorus is kept in water because –
A.
its ignition temperature is very high
B.
its ignition temperature is very low
C.
its critical temperature is high
D.
its critical temperature is low
Ans:
its ignition temperature is very low
Explanation :
The allotropic form of Phosphorus (white phosphorus) is less stable and therefore highly reactive because of angular strain in P4 molecule where the angles are only 600.
[19] The relation between bond length and bond energy is -
A.
Lower the bond energy, shorter the bond length
B.
They are not related
C.
Higher the bond energy, shorter the bond length
D.
Higher the bond energy, longer the bond length
Ans:
Higher the bond energy, shorter the bond length
Explanation :
Generally, the shorter the bond, the stronger the bond and the higher the dissociation energy. Bond energy is a measure of the strength in a chemical bond.
[20] In an atomic explosion enormous energy is released which is due to the -
A.
Conversions of neutrons into protons
B.
Conversion of chemical energy into nuclear energy
C.
Conversion of mechanical energy into nuclear energy
D.
Conversion of mass into energy
Ans:
Conversion of mass into energy
Explanation :
0
[21] Sea water is saltier than rain water because –
A.
Sea animals are salt producing
B.
The air around the sea is saltish
C.
Rivers wash away salts from earth and pour them into the sea
D.
Sea beds have salt producing mines
Ans:
Rivers wash away salts from earth and pour them into the sea
Explanation :
Seawater is salty because rainwater dissolves the salt minerals found in soil and rocks as it travels through rivers arid streams en route to the sea The rain that falls on the land contains some dissolved carbon dioxide from the surrounding air.
[22] Refrigerators keep food unspoiled because –
A.
at its low temperature, bacteria and moulds are inactive
B.
at its low temperature, the germs are killed
C.
at its low temperature, the germs are frozen
D.
it sterilizes the food
Ans:
at its low temperature, bacteria and moulds are inactive
Explanation :
Bacteria and moulds find conditions of low pH, moisture, or temperature and high salt or sugar unfavorable for their operation. This is the principle why refrigerators keep food unspoiled for a long time. Bacterial action is severely impaired at temperatures at or below 4 degree Celsius.
[23] Why is water not suitable for putting out a petrol fire?
A.
The oxygen content of water is isolated by petrol and thus it helps in burning
B.
Petrol is too inflammable to be extinguished by water
C.
The heat required for combustion of petrol is very low
D.
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Ans:
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Explanation :
Water is not effective on petrol fire because it has higher density than petrol as a result of which it sinks to the bottom, while petrol stays afloat and keeps burning. Petro-chemical fires are nearly always extinguished with chemical foam which forms a blanket over the flames and cuts off the oxygen supply.
[24] All isotopes of the same element have _.
A.
different atomic numbers and different atomic mass
B.
different atomic numbers and the same atomic mass
C.
the same atomic number but different atomic masses
D.
the same atomic number and the atomic mass
Ans:
the same atomic number but different atomic masses
Explanation :
Isotopes are forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei. So they have the same atomic number, but differ in relative atomic mass.
[25] Sodium vapour lamps glow with yellow colour. This is due to -
A.
sublimation of sodium to emit yellow colour
B.
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
C.
the low ionisation energy of sodium
D.
its ability to absorb all other colours except yellow
Ans:
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
Explanation :
Sodium Vapour Lamps glow with yellow colour due to the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum.
Explanation :
Nitrogen fixation is a process by which nitrogen in the Earth's atmosphere is converted into ammonia (NH3) or other molecules available to living organisms. Atmospheric nitrogen or molecular dinitrogen (N2) is relatively inert: it does not easily react with other chemicals to form new compounds. The fixation process frees nitrogen atoms from their triply bonded diatomic form, to be used by plants as nutrients. The conversion of organic nitrogen to proteins is achieved in Nitrogen cycle.
[16] What are soaps?
A.
Salts of silicates
B.
Ester of heavy fatty acids
C.
Sodium or potassium salts of heavier fatty acids
D.
Mixture of glycerol and alcohol
Ans:
Sodium or potassium salts of heavier fatty acids
Explanation :
0
[17] Electrolysis of an aqueous solution of copper sulphate using copper electrodes gives -
A.
Copper at eathode and oxygen at anode.
B.
Copper at anode and oxygen at cathode.
C.
Copper at cathode and anodes dissolve to give copper.
D.
Hydrogen at cathode and oxygen at anode.
Ans:
Copper at eathode and oxygen at anode.
Explanation :
Copper is deposited at the cathode and is dissolved at the anode. Consequently the concentration of copper ions in solution remains constant. This can be used as a method of purification of copper as only pure copper is deposited at the cathode
[18] Phosphorus is kept in water because –
A.
its ignition temperature is very high
B.
its ignition temperature is very low
C.
its critical temperature is high
D.
its critical temperature is low
Ans:
its ignition temperature is very low
Explanation :
The allotropic form of Phosphorus (white phosphorus) is less stable and therefore highly reactive because of angular strain in P4 molecule where the angles are only 600.
[19] The relation between bond length and bond energy is -
A.
Lower the bond energy, shorter the bond length
B.
They are not related
C.
Higher the bond energy, shorter the bond length
D.
Higher the bond energy, longer the bond length
Ans:
Higher the bond energy, shorter the bond length
Explanation :
Generally, the shorter the bond, the stronger the bond and the higher the dissociation energy. Bond energy is a measure of the strength in a chemical bond.
[20] In an atomic explosion enormous energy is released which is due to the -
A.
Conversions of neutrons into protons
B.
Conversion of chemical energy into nuclear energy
C.
Conversion of mechanical energy into nuclear energy
D.
Conversion of mass into energy
Ans:
Conversion of mass into energy
Explanation :
0
[21] Sea water is saltier than rain water because –
A.
Sea animals are salt producing
B.
The air around the sea is saltish
C.
Rivers wash away salts from earth and pour them into the sea
D.
Sea beds have salt producing mines
Ans:
Rivers wash away salts from earth and pour them into the sea
Explanation :
Seawater is salty because rainwater dissolves the salt minerals found in soil and rocks as it travels through rivers arid streams en route to the sea The rain that falls on the land contains some dissolved carbon dioxide from the surrounding air.
[22] Refrigerators keep food unspoiled because –
A.
at its low temperature, bacteria and moulds are inactive
B.
at its low temperature, the germs are killed
C.
at its low temperature, the germs are frozen
D.
it sterilizes the food
Ans:
at its low temperature, bacteria and moulds are inactive
Explanation :
Bacteria and moulds find conditions of low pH, moisture, or temperature and high salt or sugar unfavorable for their operation. This is the principle why refrigerators keep food unspoiled for a long time. Bacterial action is severely impaired at temperatures at or below 4 degree Celsius.
[23] Why is water not suitable for putting out a petrol fire?
A.
The oxygen content of water is isolated by petrol and thus it helps in burning
B.
Petrol is too inflammable to be extinguished by water
C.
The heat required for combustion of petrol is very low
D.
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Ans:
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Explanation :
Water is not effective on petrol fire because it has higher density than petrol as a result of which it sinks to the bottom, while petrol stays afloat and keeps burning. Petro-chemical fires are nearly always extinguished with chemical foam which forms a blanket over the flames and cuts off the oxygen supply.
[24] All isotopes of the same element have _.
A.
different atomic numbers and different atomic mass
B.
different atomic numbers and the same atomic mass
C.
the same atomic number but different atomic masses
D.
the same atomic number and the atomic mass
Ans:
the same atomic number but different atomic masses
Explanation :
Isotopes are forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei. So they have the same atomic number, but differ in relative atomic mass.
[25] Sodium vapour lamps glow with yellow colour. This is due to -
A.
sublimation of sodium to emit yellow colour
B.
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
C.
the low ionisation energy of sodium
D.
its ability to absorb all other colours except yellow
Ans:
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
Explanation :
Sodium Vapour Lamps glow with yellow colour due to the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum.
Explanation :
Copper is deposited at the cathode and is dissolved at the anode. Consequently the concentration of copper ions in solution remains constant. This can be used as a method of purification of copper as only pure copper is deposited at the cathode
[18] Phosphorus is kept in water because –
A.
its ignition temperature is very high
B.
its ignition temperature is very low
C.
its critical temperature is high
D.
its critical temperature is low
Ans:
its ignition temperature is very low
Explanation :
The allotropic form of Phosphorus (white phosphorus) is less stable and therefore highly reactive because of angular strain in P4 molecule where the angles are only 600.
[19] The relation between bond length and bond energy is -
A.
Lower the bond energy, shorter the bond length
B.
They are not related
C.
Higher the bond energy, shorter the bond length
D.
Higher the bond energy, longer the bond length
Ans:
Higher the bond energy, shorter the bond length
Explanation :
Generally, the shorter the bond, the stronger the bond and the higher the dissociation energy. Bond energy is a measure of the strength in a chemical bond.
[20] In an atomic explosion enormous energy is released which is due to the -
A.
Conversions of neutrons into protons
B.
Conversion of chemical energy into nuclear energy
C.
Conversion of mechanical energy into nuclear energy
D.
Conversion of mass into energy
Ans:
Conversion of mass into energy
Explanation :
0
[21] Sea water is saltier than rain water because –
A.
Sea animals are salt producing
B.
The air around the sea is saltish
C.
Rivers wash away salts from earth and pour them into the sea
D.
Sea beds have salt producing mines
Ans:
Rivers wash away salts from earth and pour them into the sea
Explanation :
Seawater is salty because rainwater dissolves the salt minerals found in soil and rocks as it travels through rivers arid streams en route to the sea The rain that falls on the land contains some dissolved carbon dioxide from the surrounding air.
[22] Refrigerators keep food unspoiled because –
A.
at its low temperature, bacteria and moulds are inactive
B.
at its low temperature, the germs are killed
C.
at its low temperature, the germs are frozen
D.
it sterilizes the food
Ans:
at its low temperature, bacteria and moulds are inactive
Explanation :
Bacteria and moulds find conditions of low pH, moisture, or temperature and high salt or sugar unfavorable for their operation. This is the principle why refrigerators keep food unspoiled for a long time. Bacterial action is severely impaired at temperatures at or below 4 degree Celsius.
[23] Why is water not suitable for putting out a petrol fire?
A.
The oxygen content of water is isolated by petrol and thus it helps in burning
B.
Petrol is too inflammable to be extinguished by water
C.
The heat required for combustion of petrol is very low
D.
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Ans:
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Explanation :
Water is not effective on petrol fire because it has higher density than petrol as a result of which it sinks to the bottom, while petrol stays afloat and keeps burning. Petro-chemical fires are nearly always extinguished with chemical foam which forms a blanket over the flames and cuts off the oxygen supply.
[24] All isotopes of the same element have _.
A.
different atomic numbers and different atomic mass
B.
different atomic numbers and the same atomic mass
C.
the same atomic number but different atomic masses
D.
the same atomic number and the atomic mass
Ans:
the same atomic number but different atomic masses
Explanation :
Isotopes are forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei. So they have the same atomic number, but differ in relative atomic mass.
[25] Sodium vapour lamps glow with yellow colour. This is due to -
A.
sublimation of sodium to emit yellow colour
B.
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
C.
the low ionisation energy of sodium
D.
its ability to absorb all other colours except yellow
Ans:
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
Explanation :
Sodium Vapour Lamps glow with yellow colour due to the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum.
Explanation :
Generally, the shorter the bond, the stronger the bond and the higher the dissociation energy. Bond energy is a measure of the strength in a chemical bond.
[20] In an atomic explosion enormous energy is released which is due to the -
A.
Conversions of neutrons into protons
B.
Conversion of chemical energy into nuclear energy
C.
Conversion of mechanical energy into nuclear energy
D.
Conversion of mass into energy
Ans:
Conversion of mass into energy
Explanation :
0
[21] Sea water is saltier than rain water because –
A.
Sea animals are salt producing
B.
The air around the sea is saltish
C.
Rivers wash away salts from earth and pour them into the sea
D.
Sea beds have salt producing mines
Ans:
Rivers wash away salts from earth and pour them into the sea
Explanation :
Seawater is salty because rainwater dissolves the salt minerals found in soil and rocks as it travels through rivers arid streams en route to the sea The rain that falls on the land contains some dissolved carbon dioxide from the surrounding air.
[22] Refrigerators keep food unspoiled because –
A.
at its low temperature, bacteria and moulds are inactive
B.
at its low temperature, the germs are killed
C.
at its low temperature, the germs are frozen
D.
it sterilizes the food
Ans:
at its low temperature, bacteria and moulds are inactive
Explanation :
Bacteria and moulds find conditions of low pH, moisture, or temperature and high salt or sugar unfavorable for their operation. This is the principle why refrigerators keep food unspoiled for a long time. Bacterial action is severely impaired at temperatures at or below 4 degree Celsius.
[23] Why is water not suitable for putting out a petrol fire?
A.
The oxygen content of water is isolated by petrol and thus it helps in burning
B.
Petrol is too inflammable to be extinguished by water
C.
The heat required for combustion of petrol is very low
D.
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Ans:
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Explanation :
Water is not effective on petrol fire because it has higher density than petrol as a result of which it sinks to the bottom, while petrol stays afloat and keeps burning. Petro-chemical fires are nearly always extinguished with chemical foam which forms a blanket over the flames and cuts off the oxygen supply.
[24] All isotopes of the same element have _.
A.
different atomic numbers and different atomic mass
B.
different atomic numbers and the same atomic mass
C.
the same atomic number but different atomic masses
D.
the same atomic number and the atomic mass
Ans:
the same atomic number but different atomic masses
Explanation :
Isotopes are forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei. So they have the same atomic number, but differ in relative atomic mass.
[25] Sodium vapour lamps glow with yellow colour. This is due to -
A.
sublimation of sodium to emit yellow colour
B.
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
C.
the low ionisation energy of sodium
D.
its ability to absorb all other colours except yellow
Ans:
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
Explanation :
Sodium Vapour Lamps glow with yellow colour due to the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum.
Explanation :
Seawater is salty because rainwater dissolves the salt minerals found in soil and rocks as it travels through rivers arid streams en route to the sea The rain that falls on the land contains some dissolved carbon dioxide from the surrounding air.
[22] Refrigerators keep food unspoiled because –
A.
at its low temperature, bacteria and moulds are inactive
B.
at its low temperature, the germs are killed
C.
at its low temperature, the germs are frozen
D.
it sterilizes the food
Ans:
at its low temperature, bacteria and moulds are inactive
Explanation :
Bacteria and moulds find conditions of low pH, moisture, or temperature and high salt or sugar unfavorable for their operation. This is the principle why refrigerators keep food unspoiled for a long time. Bacterial action is severely impaired at temperatures at or below 4 degree Celsius.
[23] Why is water not suitable for putting out a petrol fire?
A.
The oxygen content of water is isolated by petrol and thus it helps in burning
B.
Petrol is too inflammable to be extinguished by water
C.
The heat required for combustion of petrol is very low
D.
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Ans:
Water, being heavy, slips below petrol which thus remains in contact with air and burns
Explanation :
Water is not effective on petrol fire because it has higher density than petrol as a result of which it sinks to the bottom, while petrol stays afloat and keeps burning. Petro-chemical fires are nearly always extinguished with chemical foam which forms a blanket over the flames and cuts off the oxygen supply.
[24] All isotopes of the same element have _.
A.
different atomic numbers and different atomic mass
B.
different atomic numbers and the same atomic mass
C.
the same atomic number but different atomic masses
D.
the same atomic number and the atomic mass
Ans:
the same atomic number but different atomic masses
Explanation :
Isotopes are forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei. So they have the same atomic number, but differ in relative atomic mass.
[25] Sodium vapour lamps glow with yellow colour. This is due to -
A.
sublimation of sodium to emit yellow colour
B.
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
C.
the low ionisation energy of sodium
D.
its ability to absorb all other colours except yellow
Ans:
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
Explanation :
Sodium Vapour Lamps glow with yellow colour due to the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum.
Explanation :
Water is not effective on petrol fire because it has higher density than petrol as a result of which it sinks to the bottom, while petrol stays afloat and keeps burning. Petro-chemical fires are nearly always extinguished with chemical foam which forms a blanket over the flames and cuts off the oxygen supply.
[24] All isotopes of the same element have _.
A.
different atomic numbers and different atomic mass
B.
different atomic numbers and the same atomic mass
C.
the same atomic number but different atomic masses
D.
the same atomic number and the atomic mass
Ans:
the same atomic number but different atomic masses
Explanation :
Isotopes are forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei. So they have the same atomic number, but differ in relative atomic mass.
[25] Sodium vapour lamps glow with yellow colour. This is due to -
A.
sublimation of sodium to emit yellow colour
B.
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
C.
the low ionisation energy of sodium
D.
its ability to absorb all other colours except yellow
Ans:
the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
Explanation :
Sodium Vapour Lamps glow with yellow colour due to the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum.
Explanation :
Sodium Vapour Lamps glow with yellow colour due to the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum.