Chemistry Questions and Answers


Temporary hardness is due to the presence of 

   A.) magnesium sulphate
   B.) calcium bicarbonate
   C.) Calcium carbonate
   D.) calcium sulphate

Answer: Option 'B'

Temporary hardness is due to the presence of soluble bicarbonates of calcium and magnesium in water. Permanent hardness is due to the presence of sulphates and chlorides of calcium and magnesium.




Recycled plant matter is known as?

   A.) Decomposed
   B.) Carbide
   C.) Compost
   D.) None of these

Answer: Option 'C'



The freezing point of water at 760mm pressure is

   A.) 0 K
   B.) 273 K
   C.) 273 C
   D.) -273 C

Answer: Option 'B'

K is degree kelvin

Zero K corresponds to -273  K = C + 273

The freezing point of water being 0 C, on the kelvin scale it is 0 C + 273 K


Sodium carbonate crystal lose water molecules this property is called

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

Answer: Option 'A'



The substances that are composed of to or more different elements in fixed proportion by mass are called

   A.) mixture
   B.) compound
   C.) element
   D.) None of these

Answer: Option 'B'



In isotopes the number of neutrons are

   A.) same
   B.) different
   C.) both
   D.) none of these

Answer: Option 'B'



Dust particles in the air of large industrial cities are removed by

   A.) Tyndall effect
   B.) Electrophoresis
   C.) Sedimentation
   D.) Brownian movement

Answer: Option 'B'

Dust particles such as coal dust(smoke) are fine particle of a solid (carbon in the case of smoke) dispersed in air. They are colloidal systems and the particles are charged either positive or negative. In an applied electrical field, they are attracted towards the opposite electrodes. Movement of the particles towards the electrodes is known as 'electrophoresis'. Hence electrophoresis is applied to remove smoke within the chimeny itself without allowing it to escape into the air and cause nuisance.


A mixture of sand and naphthalene can be seperated by __________

   A.) Chromatography
   B.) Sublimation
   C.) Fractional distillation
   D.) Any of them

Answer: Option 'A'



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.


Rutherford's alpha-scattering experiment related to the size of the

   A.) electron
   B.) nucleus
   C.) atom
   D.) neutron

Answer: Option 'B'



The function of nitrogen in air is 

   A.) to prevent the hydrogen in air from exploding
   B.) to maintain the density of air constant
   C.) to reduce the poisonous nature of ozone in air
   D.) to make air a moderate supporter of combustion

Answer: Option 'D'

to make air a moderate supporter of combustion


Atoms Are Composed Of

   A.) Electrons and Protons
   B.) Electrons and Nuclei
   C.) Protons and Nuclei
   D.) Only Electrons

Answer: Option 'B'

Atoms are composed of Electrons, protons and Neutrons. Protons and Neutrons together called as Nuclei.


The atoms of the elements having same mass number but different atomic number are called

   A.) Isotones
   B.) Isobars
   C.) Isotopes
   D.) Isomers

Answer: Option 'B'



Heated saw dust catches fire when a drop of concentrated nitric acid is added to it. This is due to

   A.) reduction
   B.) dehydration
   C.) oxidation
   D.) dehydrogenation

Answer: Option 'C'



Acute diabets  patients smell of 

   A.) acetone
   B.) ether
   C.) ethyl alcohol
   D.) methyl alcohol

Answer: Option 'A'

Acute diabetes results in the formation of acetone in the body. Hence such patients smell of acetone.


Which one of the following laws explain the formation of carbon monoxide and carbon dioxide from carbon and oxygen

   A.) Laws of conservation of mass
   B.) Laws of multiple proportion
   C.) Laws of reciprocal proportions
   D.) Law of definite proportions

Answer: Option 'B'

Laws of multiple proportion


Which is the gas used for making vegetables and vanaspathi from vegetable oils?

   A.) Argon
   B.) Hydrogen
   C.) Nitrogen
   D.) Helium

Answer: Option 'B'

Hydrogen gas is used for making vegetables and vanaspathi from vegetable oils.

As it is colourless, odourless, tasteless, flammable gaseous substance, it is added to oils to make them more solid or spreadable.

The use of hydrogenation helps to prolong the shelf life of the food and maintain flavour stability.


The reduction potential of hydrogen half-cell will be negative if :
(1) P(H2)= 2 atm and [H+] = 2.0 M
(2) P(H2)= 1 atm and [H+] = 2.0 M
(3) P(H2)= 1 atm and [H+] = 1.0 M
(4) P(H2)= 2 atm and [H+] = 1.0 M

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

Answer: Option 'D'

Option 4


In nuclear reactor,Chain reaction is controlled by introducing

   A.) platinum rod
   B.) cadmium rod
   C.) iron rod
   D.) graphite rod

Answer: Option 'B'

cadmium rod


The purest form of iron is 

   A.) wrought iron
   B.) nickel steel
   C.) steel
   D.) pig iron

Answer: Option 'A'

Wrought Iron is the purest form of iron. It contains 0.12 to 0.25% carbonand so it is the purest form of iron.

Chemistry Questions and Answers Download Pdf