Chemistry Questions and Answers

1.

Water always contains hydrogen and oxygen in the ratio 1:8 by weight.This is in accordance with the 

   A.) Law of Conservation of mass
   B.) Law of Multiple Proportions
   C.) Law of Definite Proportion
   D.) Law of Reciprocal Proportions

Answer: Option 'C'

The Law of Definite Proportion states that the same compound, wherever found or however made, always contains the same elements combined together in the same fixede ratio by weight.

2.

PAS  is a drug used in the treatment of 

   A.) tuberculosis
   B.) Cancer
   C.) typhoid
   D.) malaria

Answer: Option 'A'

Para-amino salicyclic acid (PAS) is used in the treatment of Tuberculosis.

3.

The difference between a nuclear reactor and atomic bomb is that ___________

   A.) no chain reaction takes place in nuclear reactor while in the atomic bomb there is a chain reaction
   B.) the chain reaction in nuclear reactor is controlled
   C.) the chain reaction in nuclear reactor is not controlled
   D.) no-chain reaction takes place in atomic bomb while it takes place in nuclear reactor

Answer: Option 'B'

the chain reaction in nuclear reactor is controlled

4.

Which of the following is a Decomposition Reaction?

   A.) 2HgO ----> 2Hg + O2
   B.) 6NaNO3 ----> 6NaNO2 + 3O2
   C.) ZnCO3 ----> ZnO + CO2
   D.) All the above

Answer: Option 'D'

All the given reactions are Decomposition reactions.

Decomposition reaction is a reaction in which only one reactant is splitted into two or more products.

5.

Sodium carbonate crystal lose water molecules this property is called

   A.) efflorescence
   B.) hygroscopy
   C.) deliquescence
   D.) None of these

Answer: Option 'A'

efflorescence

6.

Among the following the maximum covalent character is shown by the compound

(1)MgCl2

(2)FeCl2

(3)SnCl2

(4) AlCl3

   A.) Option 1
   B.) Option 2
   C.) Option 3
   D.) Option 4

Answer: Option 'D'

According to Fajans rule, cation with greater charge and smaller size favours covalency.

7.

What are long chains of Carbon Molecules called

   A.) Polymers
   B.) Hydrocarbons
   C.) Ribosomes
   D.) None of these

Answer: Option 'A'

Polymers

8.

Alum is used 

   A.) as an analgesic
   B.) in the purification of water
   C.) as a fertilizer
   D.) as a disinfectant

Answer: Option 'B'

​in the purification of water

9.

If people sleep in closed rooms where charcoal fire is burning , they die due to 

   A.) carbon monoxide
   B.) carbon dioxide
   C.) methane
   D.) phosgene

Answer: Option 'A'

A closed room is aplace where charcoal is burnt in limited supply of air. There is every chance for the formation of the deadly poisonous carbon monoxide, which when inhaled, reacts with the iron in haemoglobin of blood and prevents the supply of oxygen. It is said to be treacherous as there can be no previous warning of its presence because it is an odourless and colourless gas.

10.

A mixture of ethyl alcohol  and water can be seperated  by 

   A.) using a seperating funnel
   B.) fractional distillation
   C.) sublimation
   D.) evaporation

Answer: Option 'B'

Fractional distillation is the process of seperation of a mixture of two or more liquids into the different fractions, which differ fairly widely in their boiling points. The liquid with a lower boiling point will be vaporized first and hence would be the distillate (first fraction). Eg. Ethyl alcohol has a boiling point of 78.1ºC and water 100ºC. When a mixture of these two liquids is heated, alcohol vaporizes first and is collected separately as the distillate. 

11.

The soaps used in shaving cream are 

   A.) soft soaps
   B.) Calcium soaps
   C.) lead soaps
   D.) hard soaps

Answer: Option 'A'

soft soaps

12.

In addition to nitric acid, another acid which may render iron passive is 

   A.) chromic acid
   B.) oxalic acid
   C.) citric acid
   D.) acetic acid

Answer: Option 'A'

Passivity of iron is due to formation of an extremely thin and impervious film of ferrosoferric oxide [Fe3(O4)]Fe3O4on the surface of iron. Chromic acid, being a powerful oxidising agent (like nitric acid ) renders iron passive. 

13.

Harmful bacteria in drinking water cannot be destroyed by 

   A.) Chlorination
   B.) ozonisation
   C.) adding caustic soda
   D.) boiling

Answer: Option 'C'

Water containing caustic soda cannot be used for drinking

14.

Alum is used 

   A.) as an analgesic
   B.) in the purification of water
   C.) as a fertilizer
   D.) as a disinfectant

Answer: Option 'B'

in the purification of water 

15.

Cutting and peeling of onion brings tears to the eyes because of the presence of _____ ?

   A.) Carbon
   B.) Sulfur
   C.) Amino acid
   D.) Fat

Answer: Option 'B'

Cutting and Peeling of onion brings Tears to the eyes because of presence of Sulphur in the cell.

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