Organic Chemistry Questions and Answers – Redox Reactions

This set of Organic Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Redox Reactions”.

1. KMnO₄ reacts with oxalic acid according to the equation given below. Here 20 mL of 0.1 M KMnO₄ is equivalent to how many mL and molarity of H₂C₂O₄?
2MnO₄^– + 5C2O₄^– + 16H⁺ → 2Mn⁺¹ + 10CO₂ + 8H₂O
a) 20 mL of 0.5 M H₂C₂O₄
b) 50 mL of 0.5 M H₂C₂O₄
c) 50 mL of 0.1 M H₂C₂O₄
d) 20 mL of 0.1 M H₂C₂O₄
View Answer

2. Excess of KI reacts with CuSO₄ solution and then Na₂S₂O₃ solution is added to it. Which of the statement is incorrect for this reaction?
a) Na₂S₂O₃ is oxidized
b) CuI₂ is formed
c) Cu₂I₂ is formed
d) Evolved I₂ is reduced
View Answer

3. How many number of moles of KMnO₄ will react with 180 gm H₂C₂O₄ according to given reaction?
KMnO₄ + H₂C₂O₄ → 2C0₂ + Mn²⁺
a) 4/5
b) 2/5
c) 1/5
d) 4/3
View Answer

4. What is the mass of K₂Cr₂O₇ required to produce 254 gm I₂ from KI solution? Given: K₂Cr₂O₇ + 2KI → 2Cr₃₊ + I₂
a) 49 g
b) 98 g
c) 9.8 g
d) 4.9 g
View Answer

Answer: b
Explanation:

n_eqK₂Cr₂O₇ = n_eqI₂
n × n_f = n × n_f
^w⁄_M × 6 = ^w⁄_M × 2
w/294 × 6= 254/254 × 2
w = 98g.

5. What is the volume of 0.05 M KMnO₄ which will react with 50 ml of 0.1 M H₂S in acidic medium (H₂S → S0₂)?
a) 60 ml
b) 6 ml
c) 12 ml
d) 120 ml
View Answer

Answer: d
Explanation:

n_eqKMnO₄ = n_eq H₂S
M × V × n_f = M × V × n_f
0.05 × V × 5 = 0.1 × 50 × 6
V = 120 mL.

6. What is the mass of Fe304 if it reacts completely with 25 ml of 0.3m K₂Cr₂O₇?
a) 1 .44 g
b) 10.44 g
c) 104.4 g
d) 14.4 g
View Answer

Answer: b
Explanation:

n_eqFe₃O₄ = n_eq K₂Cr₂O₇
^w⁄_M × n_f = 0.3 * 25 * 6
w = (0.3×25×6×232)/1
w = 10.44 g.

7. What is the concentration of H₂O₂ solution of 20 ml of H₂O₂ solution which will react completely with 10 ml of 2 M KMnO₄ in acidic medium?
a) 1.25 M
b) 5 M
c) 2.5 M
d) 25 M
View Answer

Answer: c
Explanation:

n_eq (H₂O₂) = n_eq (KMnO₄)
M × 20 × 2 = 2 × 10 × 5
Ans = 2.5 M.

8. How many moles of KCI are required to produce 10 mol Cl₂ by the reaction with KCIO₃?
a) 1.66 mole
b) 13.33 mole
c) 0.66 mole
d) 16.66 mole
View Answer

Answer: d
Explanation:

9. How many moles of KMnO₄ are required for complete oxidation of 1.25 mol Cu₂S?
Cu₂S → Cu⁺² + SO₂
a) 1 mole
b) 3 moles
c) 2 moles
d) 5 moles
View Answer

Answer: c
Explanation:

n_eq (KMnO₄) = n_eq (Cu₂S)
n × 5 = 1.25 × 8
n = 2.

10. What is the volume strength of H₂O₂ of its 11.2 ml requires 30 ml of 0.5 M ₂Cr₂O₇?
a) 35
b) 55
c) 25
d) 45
View Answer

Answer: d
Explanation: Volume strength of H₂O₂ = 11.2 × M H₂O₂ = 5.6 × N H₂O₂

n_eq (H₂O₂) = n_eq (KMnO₄)
M × 11.2 × 2 = 0.5 × 30 × 6
M = 4.017. Therfore, Volume strength = 11.2 × 4 = 45.

Sanfoundry Global Education & Learning Series – Organic Chemistry.

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