Topic: UNIT 4: Hydrogen



Topic: UNIT 4: Hydrogen
Q.1
Which of the following statements about hydrogen is incorrect ?
A. Hydrogen ion, H3O+ exists freely in solution.
B. Dihydrogen acts as a reducing agent.
C. Hydrogen has three isotopes of which tritium is the most common.
D. Hydrogen never acts as cation in ionic salts.
Answer : Option C
Explaination / Solution:

Correct statement : Hydrogen has three isotopes of which protium is the most common.

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Q.2
Water gas is
A. H2O (g)
B. CO + H2O
C. CO + H2
D. CO + N2
Answer : Option C
Explaination / Solution:

CO + H2 - Water gas

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Q.3
Which one of the following statements is incorrect with regard to ortho and para dihydrogen ?
A. They are nuclear spin isomers
B. Ortho isomer has zero nuclear spin whereas the para isomer has one nuclear spin
C. The para isomer is favoured at low temperatures
D. The thermal conductivity of the para isomer is 50% greater than that of the ortho isomer.
Answer : Option B
Explaination / Solution:

Correct statement : Ortho isomer - one nuclear spin

Para isomer - zero nuclear spin


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Q.4
Ionic hydrides are formed by
A. halogens
B. chalogens
C. inert gases
D. group one elements
Answer : Option D
Explaination / Solution:

eg : Sodium hydride (Na+ H)

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Q.5
Tritium nucleus contains
A. 1p + 0 n
B. 2 p + 1n
C. 1p + 2n
D. none of these
Answer : Option C
Explaination / Solution:

1T3 (1e, 1p, 2n)

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Q.6
Non-stoichiometric hydrides are formed by
A. palladium, vanadium
B. carbon, nickel
C. manganese, lithium
D. nitrogen, chlorine
Answer : Option A
Explaination / Solution:
No Explaination.


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Q.7

Assertion : Permanent hardness of water is removed by treatment with washing soda.

Reason : Washing soda reacts with soluble calcium and magnesium chlorides and sulphates in hard water to form insoluble carbonates
A. Both assertion and reason are true and reason is the correct explanation of assertion.
B. Both assertion and reason are true but reason is not the correct explanation of assertion.
C. Assertion is true but reason is false
D. Both assertion and reason are false
Answer : Option A
Explaination / Solution:

Ca2+ + Na2CO3 → CaCO3 ↓ + 2Na+

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Q.8
If a body of a fish contains 1.2 g hydrogen in its total body mass, if all the hydrogen is replaced with deuterium then the increase in body weight of the fish will be
A. 1.2 g
B. 2.4 g
C. 3.6 g
D. √4.8 g
Answer : Option A
Explaination / Solution:

mass of deuterium = 2 × mass of protium

If all the 1.2 g hydrogen is replaced with deuterium, the weight will become 2.4g. Hence the increase in body weight is (2.4 – 1.2 = 1.2 g)


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Q.9
The hardness of water can be determined by volumetrically using the reagent
A. sodium thio sulphate
B. potassium permanganate
C. hydrogen peroxide
D. EDTA
Answer : Option D
Explaination / Solution:
No Explaination.


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Q.10
The cause of permanent hardness of water is due to
A. Ca(HCO3)2
B. Mg(HCO3)2
C. CaCl2
D. MgCO3
Answer : Option C
Explaination / Solution:

Permanent hardness if water is due to the presence of the chlorides, nitrates and sulphates of Ca2+ and Mg2+ ions.

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