Class 11 Chemistry Chapter 8 Redox Reactions MCQs

Class 11 chemistry MCQs with answers are provided here for chapter 8 Redox Reactions. These MCQs are based on the CBSE board curriculum and correspond to the most recent Class 11 chemistry syllabus. By practicing 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.

Download Chapter 8 Redox Reactions MCQs PDF by clicking on the button below.
Download PDF

Class 11 Redox Reactions MCQs

1. Which of the following is not a redox reaction?

(a) Burning of candle

(b) Rusting of iron

(c) Dissolving salt in water

(d) Dissolving Zinc in dil. H₂SO₄

Ans: (c)

Solution: Dissolving salt in water is not a redox reaction.

2. The oxidation number of Cr in Cr(CO)₆ is —————–

(a) 0

(b) +2

(c) -2

(d) +6

Ans: (a)

Solution: CO is a neutral ligand whose charge is zero. In Cr(CO)6 complex, oxidation number of Cr is zero.

3. Which of the following is not a redox reaction?

(a) CaCO₃ → CaO + CO₂

(b) O₂ + 2H₂ → 2H₂O

(c) Na + H₂O → NaOH + 1/2H₂

(d) MnCl₃ → MnCl₂ + 1/2 Cl₂

Ans: (a)

Solution: CaCO₃ → CaO + CO₂

This is not a redox reaction because no element undergoes a change in oxidation number.

4. In the reaction

3Br₂ + 6CO₃^2- + 3H₂O → 5Br ^– + BrO₃^– + 6HCO₃^–

(a) Bromine is oxidised and carbonate is reduced.

(b) Bromine is reduced and water is oxidised.

(c) Bromine is neither reduced nor oxidised.

(d) Bromine is both reduced and oxidised.

Ans: (d)

Solution: In this reaction, Br₂ undergoes both decrease as well as increase in an oxidation number, it is both reduced and oxidised.

5. The most powerful oxidising agent among the following is:

(a) H₂SO₄

(b) H₃BO₃

(c) HPO₃

(d) H₃PO₄

Ans: (a)

Solution: H₂SO₄ is the most powerful oxidising agent.

6. The oxidation number of Cr in K₂Cr₂O₇ is:

(a) -6

(b) +6

(c) +2

(d) -2

Ans: (b)

Solution: In the K₂Cr₂O₇ complex, let the oxidation number of Cr be x.

Then 2(+1) + 2(x) + 7 (-2) = 0 ⇒ 2x = +12 ⇒ x = +6

7. Consider the following reaction:

Zn + Cu²⁺ → Zn²⁺ + Cu

With reference to the above, which one of the following is the correct statement?

(a) Zn is reduced to Zn²⁺ ions.

(b) Zn is oxidised to Zn²⁺ ions.

(c) Zn²⁺ ions are oxidised to Zn.

(d) Cu²⁺ ions are oxidized to Cu.

Ans: (b)

Solution: Zn is oxidised to Zn²⁺ ions by releasing electrons.

8. Oxidation number of P in PO₄^3-, of S in SO₄^2- and that of Cr in Cr₂O₇^2- are respectively:

(a) +3, +6 and +5

(b) +5, +3 and +6

(c) +3, +6 and +6

(d) +5, +6 and +6

Ans: (d)

Solution: PO₄^3- : x + 4 (-2) = -3 ⇒ x = +5

SO₄^2- : x + 4 (-2) = -2 ⇒ x = +6

Cr₂O₇^2- : 2x + 7(-2) = -2 ⇒ x = +6

9. In the reaction:

2Ag + 2H₂SO₄ → Ag₂SO₄ + 2H₂O + SO₂

Sulphuric acid acts as:

(a) Oxidising agent

(b) Reducing agent

(c) Catalyst

(d) Acid as well as oxidant

Ans: (d)

Solution: Sulphuric acid acts as acid as well as oxidant.

10. Reduction never involves:

(a) gain of electrons

(b) decrease in oxidation number

(c) loss of electrons

(d) decrease in valency of electropositive component

Ans: (c)

Solution: Reduction never involves loss of electrons

Recommended Videos