Hydrogen(12th Grade > Chemistry ) Questions and answers for exam Preparation

Question 1. The electrolysis of which of the following solution produces hydrogen peroxide?

0.2 N Na OH
50%H2SO4
2%H2SO4
5% NaCl

Explanation:-

Answer: Option B. -> 50%H2SO4
:
B
50

%

Sulphuric acid is used for large scale manufacture of

H_{2} O_{2}

Question 2.

H_{2} O_{2}

turns acidified solution of the following to orange red

TiO2
BaO2
PbO2
Na2O2

Explanation:-

Answer: Option A. -> TiO2
:
A

T i O_{2} + 2 H_{2} S O_{4} \to T i (S O_{4})_{2} + 2 H_{2} O

H_{2} O_{2} + T i (S O_{4})_{2} . 2 H_{2} O \to H_{2} T i O_{4} + 2 H_{2} S O_{4}

Orange red

Question 3. Protium differs from deuterium in

Electronic configuration
Chemical properties
Bond length
Nuclear radius

Explanation:-

Answer: Option D. -> Nuclear radius
:
D
The number of neutrons differ hence the nuclear radius

Question 4. The critical temperature of water is higher than that of

O_{2}

because

H_{2} O

molecule has

Fewer electrons than oxygen
Two covalent bonds
V-shape
Dipole moment

Explanation:-

Answer: Option D. -> Dipole moment
:
D
Critical temperature of water is more than

O_{2}

due to its dipole moment
(Dipole moment of water = 1.84 D; Dipole moment of

O_{2}

=zero D).

Question 5. Which of the following has high melting point?

H2
D2
T2
Both A and B

Explanation:-

Answer: Option C. -> T2
:
C
As atomic mass is more.

Question 6. Temporary hardness of water is due to the presence of

Magnesium bicarbonate
Calcium chloride
Magnesium sulphate
Calcium carbonate

Explanation:-

Answer: Option A. -> Magnesium bicarbonate
:
A
Chlorides and sulphates of Mg and Ca produces permanent hardness whereas bicarbonates of Mg and Ca produces temporary hardness.

Question 7.

D_{2} O

is used more in

Chemical industry
Nuclear reactor
Pharmaceutical preparations
Insecticide preparation

Explanation:-

Answer: Option B. -> Nuclear reactor
:
B
Heavy water is used in nuclear reactors to slow down fast moving neutrons and hence ensures that a certain minimum number of radioactive fission reactions can take place.

Question 8. Hydrogen will not reduce

Heated cupric oxide
Heated ferric oxide
Heated stannic oxide
Heated aluminium oxide

Explanation:-

Answer: Option D. -> Heated aluminium oxide
:
D

H_{2}

will not reduce heated

A l_{2} O_{3}

as aluminium is more reactive than hydrogen.

Question 9. The raw materials used for the preparation of permutit are

Soda ash, alumina, silica
Lime, silica, caustic soda
Zeolite, sand
Lime stone, alumina, sand

Explanation:-

Answer: Option A. -> Soda ash, alumina, silica
:
A
Permutit is sodium aluminium silicate

Question 10. Decomposition of

H_{2}

O_{2}

is a

Oxidation
Reduction
Hydrolysis
Disproportionation

Explanation:-

Answer: Option D. -> Disproportionation
:
D
Decomposition of

H_{2}

O_{2}

is Disproportionate reaction