[1] Photo chemical smog is a resultant of the reaction among –
A.
High concentration of NO2, O3, and CO in the evening
B.
CO, CO2 and NO2 at low temperature
C.
CO, O2 and peroxy acetyl nitrate in the presence of Sunlight
D.
NO2, O3 and peroxy acetyl nitrate in the presence of Sunlight
Ans:
NO2, O3 and peroxy acetyl nitrate in the presence of Sunlight
Explanation :
Photochemical smog is a unique type of air pollution which is caused by reactions between sunlight and pollutants like hydrocarbons and nitrogen dioxide (NO and NO2).
[2] During the formation of a chemical bond -
A.
energy decreases
B.
energy increases
C.
energy of the system does not change
D.
electron-electron repulsion becomes more than the nucleus-electron attraction
Ans:
energy decreases
Explanation :
0
[3] Cyanide poisoning causes death in seconds because -
A.
It denatures enzymes of the heart/muscle
B.
It breaks the electron transport chain
C.
It causes Lysis of red blood cells
D.
It causes cardiac arrest
Ans:
It causes cardiac arrest
Explanation :
Cyanide poisoning occurs on exposure to a com-pound that produces cyanide ions when dissolved in water. The cyanide ion halts cellular respiration by inhibiting an enzyme in the mitochondria called cytochrome c oxidase. If cyanide is inhaled it causes a coma with seizures, apnea, and cardiac arrest, with death following in a matter of seconds.
[4] 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. Petrochemical fires are nearly always extinguished with chemical foam.
[5] Iron and manganese present as pollutants in water cannot be re-moved by -
A.
oxidation followed by settling and filtration
B.
chlorination
C.
ion exchange process
D.
lime soda process or manganese zeolite process
Ans:
chlorination
Explanation :
Water chlorination is the process of adding chlorine or hypochlorite to water. This method is used to kill certain bacteria and other microbes in tap water as chlorine is highly toxic. In particular, chlorination is used to prevent the spread of waterborne diseases such as cholera, dysentery, typhoid etc.
[6] Which among the following is false about acids?
A.
They give H+ ions in aqueous solution
B.
Most acids contain hydrogen
C.
They turn blue litmus red
D.
They are bad conductor of electricity in aqueous solution
Ans:
They are bad conductor of electricity in aqueous solution
Explanation :
Acids are good conductors of electric current in aqueous solution. When acids come in contact with water, they liberate OH ions, resulting in conduction of electricity.
[7] What are isobars?
A.
Elements with same atomic number but different mass number
B.
Elements with different atomic number but same mass number
C.
Elements with different atomic number and different mass number
D.
Elements with same atomic number and same mass number
Ans:
Elements with different atomic number but same mass number
Explanation :
Isobars are atoms of different chemical elements that have the same number of n cleons. Correspondingly, isobars differ in atomic number (number of protons) but have the same mass number.
[8] Which of the following statements is true about Methane?
A.
It is widely used as a fuel.
B.
It is a major component of bio-gas and Compressed Natural Gas.
C.
It has a formula CH4.
D.
All of the above
Ans:
All of the above
Explanation :
All the statements mentioned above are correct. Furthermore, Hydrogen has a valency of 1 while Carbon has four valence electrons. In order to achieve noble gas configuration, carbon shares these electrons with four atoms of hydrogen resulting in formation of methane- CH4.
[9] Sulphur dioxide level in the atmosphere can be reduced by using -
A.
more efficient car engines
B.
catalytic converters in industry
C.
static electricity to attract it in factory chimneys
D.
low - sulphur fuels
Ans:
low - sulphur fuels
Explanation :
The main source of sulphur dioxide into the atmosphere is from the burning of fossil fuels. Sulphur dioxide can damage plants and reduce crop yields.
[10] Chlorine atom and chloride ions -
A.
Have an equal number of protons
B.
Have an equal number of electrons
C.
Unequal number neutrons
D.
reacts spontaneously with water
Ans:
Have an equal number of protons
Explanation :
0
[11] An atom of an element with mass number 23 and atomic number 11 will have-
A.
11 neutrons, 12 protons and 11 electrons
B.
11 protons, 12 neutrons and 11 electrons
C.
11 protons, 12 electrons and 11 neutrons
D.
23 protons and 11 electrons
Ans:
11 protons, 12 neutrons and 11 electrons
Explanation :
0
[12] Atoms of different elements have -
A.
same atomic number and same electronic configuration
B.
different atomic number and same eletronic configuration
C.
different atomic number and different number of valence electrons
D.
same number of electrons and neutrons
Ans:
different atomic number and different number of valence electrons
Explanation :
Each element's atoms have a different number of protons, neutrons, and electrons, which is why they have different atomic numbers, difference in valence electrons and other properties. Their reactivity also varies because of the number and activeness of the electrons in the atom.
[13] The molecular mass of a has is –
A.
twice its vapour pressure
B.
equal to its vapour pressure
C.
half its vapour pressure
D.
not related to its vapour pressure
Ans:
twice its vapour pressure
Explanation :
The molecular weight (molar mass) of any gas is the mass of one particle of that gas multiplie d by Avogadro's number. It is twice its vapor pressure since the molecular mass of any gas is twice its density in relation to hydrogen which has 2 atoms in one molecule. - --
[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 :
Photochemical smog is a unique type of air pollution which is caused by reactions between sunlight and pollutants like hydrocarbons and nitrogen dioxide (NO and NO2).
[2] During the formation of a chemical bond -
A.
energy decreases
B.
energy increases
C.
energy of the system does not change
D.
electron-electron repulsion becomes more than the nucleus-electron attraction
Ans:
energy decreases
Explanation :
0
[3] Cyanide poisoning causes death in seconds because -
A.
It denatures enzymes of the heart/muscle
B.
It breaks the electron transport chain
C.
It causes Lysis of red blood cells
D.
It causes cardiac arrest
Ans:
It causes cardiac arrest
Explanation :
Cyanide poisoning occurs on exposure to a com-pound that produces cyanide ions when dissolved in water. The cyanide ion halts cellular respiration by inhibiting an enzyme in the mitochondria called cytochrome c oxidase. If cyanide is inhaled it causes a coma with seizures, apnea, and cardiac arrest, with death following in a matter of seconds.
[4] 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. Petrochemical fires are nearly always extinguished with chemical foam.
[5] Iron and manganese present as pollutants in water cannot be re-moved by -
A.
oxidation followed by settling and filtration
B.
chlorination
C.
ion exchange process
D.
lime soda process or manganese zeolite process
Ans:
chlorination
Explanation :
Water chlorination is the process of adding chlorine or hypochlorite to water. This method is used to kill certain bacteria and other microbes in tap water as chlorine is highly toxic. In particular, chlorination is used to prevent the spread of waterborne diseases such as cholera, dysentery, typhoid etc.
[6] Which among the following is false about acids?
A.
They give H+ ions in aqueous solution
B.
Most acids contain hydrogen
C.
They turn blue litmus red
D.
They are bad conductor of electricity in aqueous solution
Ans:
They are bad conductor of electricity in aqueous solution
Explanation :
Acids are good conductors of electric current in aqueous solution. When acids come in contact with water, they liberate OH ions, resulting in conduction of electricity.
[7] What are isobars?
A.
Elements with same atomic number but different mass number
B.
Elements with different atomic number but same mass number
C.
Elements with different atomic number and different mass number
D.
Elements with same atomic number and same mass number
Ans:
Elements with different atomic number but same mass number
Explanation :
Isobars are atoms of different chemical elements that have the same number of n cleons. Correspondingly, isobars differ in atomic number (number of protons) but have the same mass number.
[8] Which of the following statements is true about Methane?
A.
It is widely used as a fuel.
B.
It is a major component of bio-gas and Compressed Natural Gas.
C.
It has a formula CH4.
D.
All of the above
Ans:
All of the above
Explanation :
All the statements mentioned above are correct. Furthermore, Hydrogen has a valency of 1 while Carbon has four valence electrons. In order to achieve noble gas configuration, carbon shares these electrons with four atoms of hydrogen resulting in formation of methane- CH4.
[9] Sulphur dioxide level in the atmosphere can be reduced by using -
A.
more efficient car engines
B.
catalytic converters in industry
C.
static electricity to attract it in factory chimneys
D.
low - sulphur fuels
Ans:
low - sulphur fuels
Explanation :
The main source of sulphur dioxide into the atmosphere is from the burning of fossil fuels. Sulphur dioxide can damage plants and reduce crop yields.
[10] Chlorine atom and chloride ions -
A.
Have an equal number of protons
B.
Have an equal number of electrons
C.
Unequal number neutrons
D.
reacts spontaneously with water
Ans:
Have an equal number of protons
Explanation :
0
[11] An atom of an element with mass number 23 and atomic number 11 will have-
A.
11 neutrons, 12 protons and 11 electrons
B.
11 protons, 12 neutrons and 11 electrons
C.
11 protons, 12 electrons and 11 neutrons
D.
23 protons and 11 electrons
Ans:
11 protons, 12 neutrons and 11 electrons
Explanation :
0
[12] Atoms of different elements have -
A.
same atomic number and same electronic configuration
B.
different atomic number and same eletronic configuration
C.
different atomic number and different number of valence electrons
D.
same number of electrons and neutrons
Ans:
different atomic number and different number of valence electrons
Explanation :
Each element's atoms have a different number of protons, neutrons, and electrons, which is why they have different atomic numbers, difference in valence electrons and other properties. Their reactivity also varies because of the number and activeness of the electrons in the atom.
[13] The molecular mass of a has is –
A.
twice its vapour pressure
B.
equal to its vapour pressure
C.
half its vapour pressure
D.
not related to its vapour pressure
Ans:
twice its vapour pressure
Explanation :
The molecular weight (molar mass) of any gas is the mass of one particle of that gas multiplie d by Avogadro's number. It is twice its vapor pressure since the molecular mass of any gas is twice its density in relation to hydrogen which has 2 atoms in one molecule. - --
[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 :
Cyanide poisoning occurs on exposure to a com-pound that produces cyanide ions when dissolved in water. The cyanide ion halts cellular respiration by inhibiting an enzyme in the mitochondria called cytochrome c oxidase. If cyanide is inhaled it causes a coma with seizures, apnea, and cardiac arrest, with death following in a matter of seconds.
[4] 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. Petrochemical fires are nearly always extinguished with chemical foam.
[5] Iron and manganese present as pollutants in water cannot be re-moved by -
A.
oxidation followed by settling and filtration
B.
chlorination
C.
ion exchange process
D.
lime soda process or manganese zeolite process
Ans:
chlorination
Explanation :
Water chlorination is the process of adding chlorine or hypochlorite to water. This method is used to kill certain bacteria and other microbes in tap water as chlorine is highly toxic. In particular, chlorination is used to prevent the spread of waterborne diseases such as cholera, dysentery, typhoid etc.
[6] Which among the following is false about acids?
A.
They give H+ ions in aqueous solution
B.
Most acids contain hydrogen
C.
They turn blue litmus red
D.
They are bad conductor of electricity in aqueous solution
Ans:
They are bad conductor of electricity in aqueous solution
Explanation :
Acids are good conductors of electric current in aqueous solution. When acids come in contact with water, they liberate OH ions, resulting in conduction of electricity.
[7] What are isobars?
A.
Elements with same atomic number but different mass number
B.
Elements with different atomic number but same mass number
C.
Elements with different atomic number and different mass number
D.
Elements with same atomic number and same mass number
Ans:
Elements with different atomic number but same mass number
Explanation :
Isobars are atoms of different chemical elements that have the same number of n cleons. Correspondingly, isobars differ in atomic number (number of protons) but have the same mass number.
[8] Which of the following statements is true about Methane?
A.
It is widely used as a fuel.
B.
It is a major component of bio-gas and Compressed Natural Gas.
C.
It has a formula CH4.
D.
All of the above
Ans:
All of the above
Explanation :
All the statements mentioned above are correct. Furthermore, Hydrogen has a valency of 1 while Carbon has four valence electrons. In order to achieve noble gas configuration, carbon shares these electrons with four atoms of hydrogen resulting in formation of methane- CH4.
[9] Sulphur dioxide level in the atmosphere can be reduced by using -
A.
more efficient car engines
B.
catalytic converters in industry
C.
static electricity to attract it in factory chimneys
D.
low - sulphur fuels
Ans:
low - sulphur fuels
Explanation :
The main source of sulphur dioxide into the atmosphere is from the burning of fossil fuels. Sulphur dioxide can damage plants and reduce crop yields.
[10] Chlorine atom and chloride ions -
A.
Have an equal number of protons
B.
Have an equal number of electrons
C.
Unequal number neutrons
D.
reacts spontaneously with water
Ans:
Have an equal number of protons
Explanation :
0
[11] An atom of an element with mass number 23 and atomic number 11 will have-
A.
11 neutrons, 12 protons and 11 electrons
B.
11 protons, 12 neutrons and 11 electrons
C.
11 protons, 12 electrons and 11 neutrons
D.
23 protons and 11 electrons
Ans:
11 protons, 12 neutrons and 11 electrons
Explanation :
0
[12] Atoms of different elements have -
A.
same atomic number and same electronic configuration
B.
different atomic number and same eletronic configuration
C.
different atomic number and different number of valence electrons
D.
same number of electrons and neutrons
Ans:
different atomic number and different number of valence electrons
Explanation :
Each element's atoms have a different number of protons, neutrons, and electrons, which is why they have different atomic numbers, difference in valence electrons and other properties. Their reactivity also varies because of the number and activeness of the electrons in the atom.
[13] The molecular mass of a has is –
A.
twice its vapour pressure
B.
equal to its vapour pressure
C.
half its vapour pressure
D.
not related to its vapour pressure
Ans:
twice its vapour pressure
Explanation :
The molecular weight (molar mass) of any gas is the mass of one particle of that gas multiplie d by Avogadro's number. It is twice its vapor pressure since the molecular mass of any gas is twice its density in relation to hydrogen which has 2 atoms in one molecule. - --
[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 :
Water chlorination is the process of adding chlorine or hypochlorite to water. This method is used to kill certain bacteria and other microbes in tap water as chlorine is highly toxic. In particular, chlorination is used to prevent the spread of waterborne diseases such as cholera, dysentery, typhoid etc.
[6] Which among the following is false about acids?
A.
They give H+ ions in aqueous solution
B.
Most acids contain hydrogen
C.
They turn blue litmus red
D.
They are bad conductor of electricity in aqueous solution
Ans:
They are bad conductor of electricity in aqueous solution
Explanation :
Acids are good conductors of electric current in aqueous solution. When acids come in contact with water, they liberate OH ions, resulting in conduction of electricity.
[7] What are isobars?
A.
Elements with same atomic number but different mass number
B.
Elements with different atomic number but same mass number
C.
Elements with different atomic number and different mass number
D.
Elements with same atomic number and same mass number
Ans:
Elements with different atomic number but same mass number
Explanation :
Isobars are atoms of different chemical elements that have the same number of n cleons. Correspondingly, isobars differ in atomic number (number of protons) but have the same mass number.
[8] Which of the following statements is true about Methane?
A.
It is widely used as a fuel.
B.
It is a major component of bio-gas and Compressed Natural Gas.
C.
It has a formula CH4.
D.
All of the above
Ans:
All of the above
Explanation :
All the statements mentioned above are correct. Furthermore, Hydrogen has a valency of 1 while Carbon has four valence electrons. In order to achieve noble gas configuration, carbon shares these electrons with four atoms of hydrogen resulting in formation of methane- CH4.
[9] Sulphur dioxide level in the atmosphere can be reduced by using -
A.
more efficient car engines
B.
catalytic converters in industry
C.
static electricity to attract it in factory chimneys
D.
low - sulphur fuels
Ans:
low - sulphur fuels
Explanation :
The main source of sulphur dioxide into the atmosphere is from the burning of fossil fuels. Sulphur dioxide can damage plants and reduce crop yields.
[10] Chlorine atom and chloride ions -
A.
Have an equal number of protons
B.
Have an equal number of electrons
C.
Unequal number neutrons
D.
reacts spontaneously with water
Ans:
Have an equal number of protons
Explanation :
0
[11] An atom of an element with mass number 23 and atomic number 11 will have-
A.
11 neutrons, 12 protons and 11 electrons
B.
11 protons, 12 neutrons and 11 electrons
C.
11 protons, 12 electrons and 11 neutrons
D.
23 protons and 11 electrons
Ans:
11 protons, 12 neutrons and 11 electrons
Explanation :
0
[12] Atoms of different elements have -
A.
same atomic number and same electronic configuration
B.
different atomic number and same eletronic configuration
C.
different atomic number and different number of valence electrons
D.
same number of electrons and neutrons
Ans:
different atomic number and different number of valence electrons
Explanation :
Each element's atoms have a different number of protons, neutrons, and electrons, which is why they have different atomic numbers, difference in valence electrons and other properties. Their reactivity also varies because of the number and activeness of the electrons in the atom.
[13] The molecular mass of a has is –
A.
twice its vapour pressure
B.
equal to its vapour pressure
C.
half its vapour pressure
D.
not related to its vapour pressure
Ans:
twice its vapour pressure
Explanation :
The molecular weight (molar mass) of any gas is the mass of one particle of that gas multiplie d by Avogadro's number. It is twice its vapor pressure since the molecular mass of any gas is twice its density in relation to hydrogen which has 2 atoms in one molecule. - --
[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 :
Isobars are atoms of different chemical elements that have the same number of n cleons. Correspondingly, isobars differ in atomic number (number of protons) but have the same mass number.
[8] Which of the following statements is true about Methane?
A.
It is widely used as a fuel.
B.
It is a major component of bio-gas and Compressed Natural Gas.
C.
It has a formula CH4.
D.
All of the above
Ans:
All of the above
Explanation :
All the statements mentioned above are correct. Furthermore, Hydrogen has a valency of 1 while Carbon has four valence electrons. In order to achieve noble gas configuration, carbon shares these electrons with four atoms of hydrogen resulting in formation of methane- CH4.
[9] Sulphur dioxide level in the atmosphere can be reduced by using -
A.
more efficient car engines
B.
catalytic converters in industry
C.
static electricity to attract it in factory chimneys
D.
low - sulphur fuels
Ans:
low - sulphur fuels
Explanation :
The main source of sulphur dioxide into the atmosphere is from the burning of fossil fuels. Sulphur dioxide can damage plants and reduce crop yields.
[10] Chlorine atom and chloride ions -
A.
Have an equal number of protons
B.
Have an equal number of electrons
C.
Unequal number neutrons
D.
reacts spontaneously with water
Ans:
Have an equal number of protons
Explanation :
0
[11] An atom of an element with mass number 23 and atomic number 11 will have-
A.
11 neutrons, 12 protons and 11 electrons
B.
11 protons, 12 neutrons and 11 electrons
C.
11 protons, 12 electrons and 11 neutrons
D.
23 protons and 11 electrons
Ans:
11 protons, 12 neutrons and 11 electrons
Explanation :
0
[12] Atoms of different elements have -
A.
same atomic number and same electronic configuration
B.
different atomic number and same eletronic configuration
C.
different atomic number and different number of valence electrons
D.
same number of electrons and neutrons
Ans:
different atomic number and different number of valence electrons
Explanation :
Each element's atoms have a different number of protons, neutrons, and electrons, which is why they have different atomic numbers, difference in valence electrons and other properties. Their reactivity also varies because of the number and activeness of the electrons in the atom.
[13] The molecular mass of a has is –
A.
twice its vapour pressure
B.
equal to its vapour pressure
C.
half its vapour pressure
D.
not related to its vapour pressure
Ans:
twice its vapour pressure
Explanation :
The molecular weight (molar mass) of any gas is the mass of one particle of that gas multiplie d by Avogadro's number. It is twice its vapor pressure since the molecular mass of any gas is twice its density in relation to hydrogen which has 2 atoms in one molecule. - --
[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 main source of sulphur dioxide into the atmosphere is from the burning of fossil fuels. Sulphur dioxide can damage plants and reduce crop yields.
[10] Chlorine atom and chloride ions -
A.
Have an equal number of protons
B.
Have an equal number of electrons
C.
Unequal number neutrons
D.
reacts spontaneously with water
Ans:
Have an equal number of protons
Explanation :
0
[11] An atom of an element with mass number 23 and atomic number 11 will have-
A.
11 neutrons, 12 protons and 11 electrons
B.
11 protons, 12 neutrons and 11 electrons
C.
11 protons, 12 electrons and 11 neutrons
D.
23 protons and 11 electrons
Ans:
11 protons, 12 neutrons and 11 electrons
Explanation :
0
[12] Atoms of different elements have -
A.
same atomic number and same electronic configuration
B.
different atomic number and same eletronic configuration
C.
different atomic number and different number of valence electrons
D.
same number of electrons and neutrons
Ans:
different atomic number and different number of valence electrons
Explanation :
Each element's atoms have a different number of protons, neutrons, and electrons, which is why they have different atomic numbers, difference in valence electrons and other properties. Their reactivity also varies because of the number and activeness of the electrons in the atom.
[13] The molecular mass of a has is –
A.
twice its vapour pressure
B.
equal to its vapour pressure
C.
half its vapour pressure
D.
not related to its vapour pressure
Ans:
twice its vapour pressure
Explanation :
The molecular weight (molar mass) of any gas is the mass of one particle of that gas multiplie d by Avogadro's number. It is twice its vapor pressure since the molecular mass of any gas is twice its density in relation to hydrogen which has 2 atoms in one molecule. - --
[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
[12] Atoms of different elements have -
A.
same atomic number and same electronic configuration
B.
different atomic number and same eletronic configuration
C.
different atomic number and different number of valence electrons
D.
same number of electrons and neutrons
Ans:
different atomic number and different number of valence electrons
Explanation :
Each element's atoms have a different number of protons, neutrons, and electrons, which is why they have different atomic numbers, difference in valence electrons and other properties. Their reactivity also varies because of the number and activeness of the electrons in the atom.
[13] The molecular mass of a has is –
A.
twice its vapour pressure
B.
equal to its vapour pressure
C.
half its vapour pressure
D.
not related to its vapour pressure
Ans:
twice its vapour pressure
Explanation :
The molecular weight (molar mass) of any gas is the mass of one particle of that gas multiplie d by Avogadro's number. It is twice its vapor pressure since the molecular mass of any gas is twice its density in relation to hydrogen which has 2 atoms in one molecule. - --
[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 molecular weight (molar mass) of any gas is the mass of one particle of that gas multiplie d by Avogadro's number. It is twice its vapor pressure since the molecular mass of any gas is twice its density in relation to hydrogen which has 2 atoms in one molecule. - --
[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.