Top 1000+ Solved Chemistry MCQ Questions Answer
Q. 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.
Q. 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
Q. 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
Q. 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
Q. 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
Q. 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
Q. 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
Q. 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
Q. 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
Q. Photo chemical smog is a result-ant 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
Q. 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
Q. 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
Q. 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
Q. 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
Q. 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