Class 11 Chemistry Chapter 9 Hydrogen MCQs

Class 11 chemistry MCQs with answers are provided here for chapter 9 Hydrogen. These MCQs are based on the CBSE board curriculum and correspond to the most recent Class 11 chemistry syllabus. By practising these Class 11 Multiple choice questions, students will be able to quickly review all of the ideas covered in the chapter and prepare for the Class 11 Annual examinations as well as other entrance exams such as NEET and JEE.

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Class 11 Hydrogen MCQs

1. Hardness of water is due to the pair of ions

(a) Ca²⁺ and K⁺

(b) Mg²⁺ and K⁺

(c) Ca²⁺ and Mg²⁺

(d) Ba²⁺ and Zn²⁺

Ans: (c)

Solution: Ca²⁺ and Mg²⁺ ions cause the hardness of water.

2. Nascent hydrogen consists of

(a) Hydrogen atoms with excess energy

(b) Hydrogen molecules with excess energy

(c) Hydrogen ions within the excited state

(d) Solvated protons

Ans: (a)

Solution: Nascent hydrogen [H] consists of hydrogen atoms with excess energy.

3. Moist H₂O₂ cannot be dried over conc. H₂SO₄ because:

(a) it can catch fire

(b) it is reduced by H₂SO₄

(c) it is oxidised by H₂SO₄

(d) None of these is true

Ans: (c)

Solution: Moist H₂O₂ cannot be dried over conc. H₂SO₄ because it is oxidised by H₂SO₄

4. The adsorption of hydrogen by palladium is called ———–

(a) Hydrogenation

(b) Hydration

(c) Reduction

(d) Occlusion

Ans: (d)

Solution: Adsorption of  gas on the metal surface is called occlusion.

5. Which is used as a moderator in a nuclear reactor?

(a) H₂O

(b) Alum

(c) D₂O

(d) Any of these

Ans: (c)

Solution: D₂O (Heavy water) is used as a moderator in nuclear reactors.

6. Zeolite used to soften hardness of water is hydrated:

(a) Potassium aluminium borate

(b) Sodium aluminium silicate

(c) Calcium aluminium silicate

(d) Zinc aluminium borate

Ans: (b)

Solution: Zeolite used to soften the hardness of water is hydrated sodium aluminium silicate.

7. Permanent hardness from water can be removed by adding ————-

(a) Na₂CO₃

(b) K

(c) Ca(OCl)Cl

(d) Cl₂

Ans: (a)

Solution: Na₂CO₃ removes permanent hardness from water

8. The reagent(s) used for softening the temporary hardness of water is(are) ———-

(a) Ca₃(PO₄)₂

(b) Ca(OH)₂

(c) Na₂CO₃

(d) Cl₂

Ans: (b, c)

Solution: Both Ca(OH)₂ and Na₂CO₃ can remove temporary hardness from water.

9. Which of the following statements about hydrogen is incorrect?

(a) Hydronium ion, H₃O⁺ exists freely in solution.

(b) Dihydrogen does not act as a reducing agent.

(c) Hydrogen has three isotopes of which tritium is the most common.

(d) Hydrogen never acts as a cation in ionic salts.

Ans: (b , c)

Solution: Dihydrogen can act as a powerful reducing agent.

Example CuO + H₂ → Cu + H₂O.

Out of three isotopes, protium (₁H¹) is the most common.

10. Water softening by Clarke’s process uses:

(a) Calcium bicarbonate

(b) Sodium bicarbonate

(c) potash alum

(d) Calcium hydroxide

Ans: (d)

Solution: Water softening by Clarke’s process uses calcium hydroxide.