NCERT Class 11 Chemistry Chapter 8 Redox Reactions Multiple Choice Questions

NCERT Solutions For Class 11 Chemistry Chapter 8 Redox Reactions Multiple Choice Questions

Question 1. Oxidation numbers of S in peroxonosulphric and peroxonosulphric acids respectively are-

1. +3 and +3
2. +4 and +6
3. +6 and +6
4. +8 and +7

Answer: 2. +4 and +6

Question 2. The oxidation number of pyrophosphoriqaeid is-

1. +1
2. +3
3. +4
4. +5

Answer: 4. +5

Question 3. When SO₂ gas is passed through an acidic solution of K₂Gr₂O₇, the oxidation number of S changes by

1. 2 unit
2. 3 unit
3. 4 unit
4. 6 unit

Answer: 1. 2 unit

Question 4. When manganous salt is fused with KNO₃ and solid NaOH, the oxidation number changes from

1. +2 to +3
2. +2 to +4
3. +2 to +6
4. +2 to +7

Answer: 3. +2 to +6

Question 5. Which ofthe following reactions is not a redox reaction

1. 2CuSO₄ + 4KI→ Cu₂I₂ + 2K₂SO₄ + I₂
2. SO₂ + H₂O→H₂SO₃
3. CuSO₄ + 4NH₃→ [Cu(NH₃)4]SO₄
4. 4KClO₃ →3KC1O₄ + KCl

Answer: 3. CuSO₄ + 4NH₃→ [Cu(NH₃)4]SO₄

Question 6. Which of the following reactions does the reaction, Ag²⁺ + Ag→Ag⁺, belong to

1. Reduction
2. Oxidation
3. Comproportionation
4. Disproportionation

Answer: 3. Comproportionation

Question 7. In the following reaction, the oxidation half-reaction gives, 2KMnO₄ + 5H₂C₂O₄ + 3H₂SO₄ →  K₂SO₄ + 2MnSO₄+ 10CO₂ + 8H₂O

1. MnSO₄
2. CO₂
3. K₂SO₄
4. H₂O

Answer: 2. CO₂

Question 8. The amount of electrons required to reduce 1 mol of nitrate ions to hydrazine is-

1. 7 mol
2. 6 mol
3. 5 mol
4. 4 mol

Answer: 1. 7 mol

Question 9. The reaction of ClO₂ with H₂O₂ in an alkaline medium results in O₂ and Cl^– ions. In this reaction, ClO₂ acts as an oxidant. The number of mol of H₂O₂ oxidized by 1 mol of ClO₂ is

1. 1.0
2. 1.2
3. 2.5
4. 2.8

Answer: 3. 2.5

Question 10. In the balanced equation of the reaction,

⇒  \(\mathrm{Zn}+\mathrm{NO}_3^{-}+\mathrm{OH}^{-} \rightarrow \mathrm{ZnO}_2^{2-}+\mathrm{NH}_3\), the coefficients of Zn, NO₃ and OH^– respectively are—

1. 1,4 and 8
2. 8,3 and 2
3. 4,1 and 7
4. 5,2 and 8

Answer: 3. 4,1 and 7

Question 11. The amount of iodine that liberates in the reaction of 0.1 mol of K₂Cr₂O? with an excess of K₃ in an acidic solution is

1. 0.1 mol
2. 0.2 mol
3. 0.3 mol
4. 0.4 mol

Answer: 3. 0.3 mol

Question 12. In a strong alkaline solution, the equivalent mass of KMnO₄ (molecular mass =M) is—

1. M/5
2. M/2
3. M/2
4. M

Answer: 4. M

Question 13. In the balanced equation for the reaction,

⇒ \(\mathrm{As}_2 \mathrm{~S}_3+a \mathrm{ClO}_3^{-}+b \mathrm{OH}^{-}\) →  \(x \mathrm{AsO}_4^{3-}+y \mathrm{ClO}^{-} \div z \mathrm{SO}_4^{2-} \div 6 \mathrm{H}_2 \mathrm{O}\) the values of a and b respectively are-

1. 3 and 7
2. 8 and 3
3. 5 and 2
4. 6 and 8

Answer: 2. 8 and 3

Question 14. In the reaction of KMnO₄ with ferrous ions in an acidic medium, KMnO₄ oxidizes ferrous ions to ferric ions and itself gets reduced to manganous salt. The number of ferrous ions oxidized by 100 mL of 0.2(N) KMnO₄ solution is

1. 1.117 g
2. 1.562 g
3. 2.173 g
4. 1.934 g

Answer: 1. 1.117 g

Question 15. The oxidation number of B in NaBH₄ is 

1. -3
2. +3
3. +2
4. -4

Answer: 2. +3

Question 16. The equivalent mass of the oxidant in the reaction, 3Cl₂ + 6NaOH→5NaCl + NaClO₃ + 3H₂O is

1. 71
2. 14.2
3. 7.1
4. 35.5

Answer: 3. 7.1

Question 17. \(\mathrm{Cr}(\mathrm{OH})_3+\mathrm{IO}_3^{-}+\mathrm{OH}^{-} \rightarrow \mathrm{CrO}_4^{2-}+\mathrm{H}_2 \mathrm{O}+\mathrm{I}_2\) In the balanced equation of this reaction, the coefficient of H₂O is-

1. 2
2. 3
3. 4
4. 5

Answer: 4. 5

Question 18. In the balanced equation for the reaction-

⇒ \(\mathrm{As}_2 \mathrm{~S}_3+a \mathrm{ClO}_3^{-}+b \mathrm{OH}^{-}\)→ \( x \mathrm{AsO}_4^{3-}+y \mathrm{ClO}^{-}+z \mathrm{SO}_4^{2-}+6 \mathrm{H}_2 \mathrm{O}\)

1. x+y+z=a
2. a+x+z=b
3. a-x-z=y
4. b-a=y-z

Answer: 2. a+x+z=b

Question 19. In the reaction, Fe₃O₄ + KMnO₄ → Fe₂O₃ +MnO₂, the equivalent mass of Fe₃O₄ is

1. 116
2. 232
3. 773
4. 154.6

Answer: 2. 232

Question 20. Which of the following requires an oxidant

1. Cu²⁺→ Cu

2. Cu₃P₂→2PH₃

3. \(2 \mathrm{~S}_2 \mathrm{O}_3^{2-} \rightarrow \mathrm{S}_4 \mathrm{O}_6^{2-}\)

4. \(\mathrm{SO}_3 \rightarrow \mathrm{SO}_4^{2-}\)

Answer: 3. \(2 \mathrm{~S}_2 \mathrm{O}_3^{2-} \rightarrow \mathrm{S}_4 \mathrm{O}_6^{2-}\)

Question 21. In the presence of HCl(aq), K₂Cr₂O₇ oxidizes tin (Sn) into Sn⁴⁺ ions. The amount of that will be oxidisedby1 mol K₂Cr₂O₇ is 

1. 1.0 mol
2. 1.5 mol
3. 2.0 mol
4. 2.5 mol

Answer: 2. 1.5 mol

Question 22. The amount of Na₂S₂O₃ required for reducing iodine produced by the reaction of mol ofKI with H₂O₂ in an acid medium is

1. 0.5 mol
2. 1 mol
3. 2 mol
4. 2.5 mol

Answer: 3. 2 mol

Question 23. The ratio of equivalent masses of KMnO₄ in acidic, strong alkaline, and neutral solutions is

1. 3:5:15
2. 3:15:5
3. 5:5:3
4. 3:3:5

Answer: 2. 3:15:5

Question 24. The amount of H₂O₂ required for decolorizing 1 mol of KMnO₄ in an acid solution is

1. 1.5 mol
2. 2.0 mol
3. 2.5 mol
4. 3.0 mol

Answer: 3. 2.5 mol

Question 25. Fe has the lowest oxidation state in

1. FeSO₄(NH₄)₂SO₄.6H₂O
2. K₄[Fe(CN)g]
3. Fe(CO)₅
4. Fe_0.94O

Answer: 3. Fe(CO)₅

Question 26. A compound of Xe and F is found to have 53.5% Xe. What is the oxidation number of Xein in this compound?

1. -4
2. 0
3. +4
4. +6

Answer: 4. +6

Question 27. A disproportionation reaction is not possible for

1. ASH₃
2. SF₄
3. H₅IO₆
4. PCl₃

Answer: 3. PCl₃

Question 28. When lmol of KClO₃ accepts 4 t nol of electrons, the expected product is

1. ClO^–₂
2. ClO^–₄
3. OCl^–
4. Cl^–

Answer: 3.  OCl^–

Question 29. \(\mathrm{M}^{x+}+\mathrm{MnO}_4^{-} \rightarrow \mathrm{MO}_3^{-}+\mathrm{Mn}^{2+}+\frac{1}{2} \mathrm{O}_2\) If 1 mol of MnO₄ oxidises 2.5 mol of M-v+, then the value of X is 

1. 5
2. 3
3. 4
4. 1

Answer: 4. 1

Question 30. During the reaction between KClO₃ and (COOH)₂ in an acidic medium, the tire element that undergoes a maximum change in the oxidation number is

1. K
2. O
3. Cl
4. C

Answer: 3. Cl

Question 31. If the oxidation numbers of Cr in CrOg, K₂CrO₄  K,Cr₂O^– and [Cr(NH₃)₄Cl₂]Cl are +a, +b, +c and +d respectively, then

1. a>c>b>d
2. a=x>b>d
3. a=b>c>d
4. a=b=c>d

Answer: 2. a=x>b>d

Question 32. The oxidation number of Pt in [Pt(C₂H₄)Cl₃]^– is

1. +3
2. +4
3. +2
4. O

Answer: 3. +2

Question 34. For the reaction:

⇒  \(\mathrm{H}_2 \mathrm{O}_2+x \mathrm{ClO}_2 \rightarrow x \mathrm{Cl}^{-}+y \mathrm{O}_2+\mathrm{H}_2 \mathrm{O}\) the value of y/x is

1. 2.0
2. 2.5
3. 1.0
4. 1.5

Answer: 2. 2.5

Question 35. The oxidation number of Ba(H₂PO₂)₂ is

1. +3
2. +2
3. +1
4. -1

Answer: 3. +1

Question 36. \(a \mathrm{Mn}^{2+}+b \mathrm{BiO}_3^{-}+c \mathrm{H}^{+}=\mathrm{I}^{-} \mathrm{MnO}_4^{-}+b \mathrm{Bi}^{3+}+d \mathrm{H}_2 \mathrm{O}\)

1. a = 3
2. b = 5
3. c =10
4. d = 6

Answer: 2. b = 5

Question 37. The mixture of NaOH solution and white P on heating produces PH₃ gas and Na₂H₂PO₂. The above reaction is an example of

1. Oxidation reaction
2. Reduction reaction
3. Comproportionation reaction
4. Disproportionation reaction

Answer: 4. Disproportionation reaction

Question 38. For the reaction:

⇒ \(\mathrm{Zn}(\mathrm{s})+\mathrm{HNO}_3(a q) \longrightarrow\) \(\mathrm{Zn}\left(\mathrm{NO}_3\right)_2(a q)+\mathrm{NH}_4 \mathrm{NO}_3(a q)+\mathrm{H}_2 \mathrm{O}(l)\)

The change in oxidation number per mole HNO₃ is

1. Increases by 6 unit
2. Decreases by 4 unit
3. Decreases by 8 unit
4. Decreases by 6 unit

Answer: 3. Decreases by 8 unit

Question 39. To balance the chemical equation

⇒ \(\mathrm{Cl}_2 \mathrm{O}_7(\mathrm{~g})+\mathrm{H}_2 \mathrm{O}(l)+x e \rightarrow \mathrm{ClO}_2^{-}(a q)+\mathrm{OH}^{-}(a q)\) the value of x should be-

1. 8
2. 6
3. 5
4. 4

Answer: 2. 6

Question 40. Find the equivalent mass of Na₂S₂O₃ for the reaction

⇒ \(2 \mathrm{Na}_2 \mathrm{~S}_2 \mathrm{O}_3(a q)+\mathrm{I}_2(\mathrm{~s}) \rightarrow \mathrm{Na}_2 \mathrm{~S}_4 \mathrm{O}_6(a q)+\mathrm{NaI}(a q)\)

[Assume that the molecular mass of Na₂S₂O₃ is M]

1. M/8
2. M
3. M/2
4. M/4

Answer: 2. M