Refrigeration helps in food preservation by

1)  greatly reducing the rates by biochemical reaction

2)  sealing the food with a layer of ice

3)  destroying enzyme action

4)  killing the germs

In the experiment for determining the percentage of water absorbed by raisins, we do the final weighing of the raisins after keeping them dipped in water for about one hour. For the accuracy of the result, the extra water from the surface of the soaked raisins is removed by :

1) rubbing with cotton cloth

2) hot air blower

3) dry cotton wool

4) filter paper

The maximum number of isomers (including stereoisomers) that are possible on monochlorination of the following compound, is


1) 4
2) 7
3) 6
4) 8

Which of the following is correctly matched?

1) C - C bond length --- >0.077nm
2) Ionic radius of Na+ ---> 0.136 nm
3) C - Cl bond length --- >0.176 nm
4) Ionic radius of F- --- >0.095 nm

Amines behave as :

1) Lewis acids
2) Lewis bases
3) Amphoteric compounds
4) Neutral compounds

Styrene can be purified by:

1) Simple distillation

2) Fractional distillation

3) Vacuum distillation

4) Steam distillation

Benzene is unreactive because :

 1) It has carbon - carbon single bonds
2) It has double bonds
3) p electrons are delocalised
4) Carbons are sp2 hybridised

Leaching of Ag₂S is carried out by heating it with a dilute solution of:

1) NaCN only
2) HCl
3) NaOH
4) NaCN in presence of O₂

At temperature TK, K_p for the reaction of CO₂ with excess of hot graphite to form CO is 9 atm. Calculate the mole% of CO in the equilibrium mixture of gases at a pressure of 4 atm?

1) 55%
2) 25%
3) 30%
4) 75%

Magnesium reacts with acids producing hydrogen and corresponding magnesium salts. In such reactions Mg undergoes.

1) Reduction
2) Oxidation
3) Neither oxidation nor reduction
4) Simple dissolution