Redox Reactions MCQ Questions and Answers for Practice

1. The colorless solution of silver nitrate slowly turns brown on adding copper chips to it because of

1. Dissolution of Copper
2. Oxidation of Ag⁺ -> Ag
3. Reduction of Cu²⁺ ions
4. Oxidation of Cu atoms

2. The oxidation process involves

1. Increase in oxidation number
2. Decrease in oxidation number
3. No change in oxidation number
4. none of the above

3. The oxidation number of Mn is maximum in

1. MnO₂
2. K₂MnO₄
3. Mn₃O₄
4. KMnO₄

4. KMnO₄ reacts with oxalic acid according to the equation 2MnO₄^- + 5C₂O₄^2- + 16H⁺ -> 2Mn₂+ +10CO₂ + 8H₂O , Here 20 mL of 0.1 M KMnO₄ is equivalent to

1. 50 mL of 0.5 M C₂H₂O₄
2. 20 mL of 0.1 M C₂H₂O₄
3. 20 mL of 0.5 M C₂H₂O₄
4. 50 mL of 0.1 M C₂H₂O₄

5. Which of the following reactions does not involve either oxidation or reduction?

1. VO₂⁺ -> V₂O₃
2. Na -> Na⁺
3. CrO₂^-4 -> Cr₂O₇^2-
4. Zn²⁺ -> Zn

6. The number of moles of KMnO₄ reduced by one mole of KI in alkaline medium is

1. One
2. Two
3. Five
4. One fifth

7. Which of the following processes does not involve oxidation of iron?

1. Formation of Fe (CO)₅ from Fe.
2. Liberation of H₂ from steam by iron at high temperature.
3. Rusting of iron sheets.
4. Decolorization of blue CuSO₄ solution by iron.

8. The oxidation state of Cr in Cr (CO)₆ is

1. 0
2. 2
3. 4
4. 6

9. Which of the following processes does not involve either oxidation or reduction?

1. Formation of slaked lime from quick lime
2. Heating Mercuric Oxide
3. Formation of Manganese Chloride from Manganese oxide
4. Formation of Zinc from Zinc blende

10. The oxidation number of Cl in Cl₂O₇ is

1. +7
2. 5
3. 3
4. -7

11. A metal ion M³⁺ loses 3 electrons, its oxidation number will be

1. 3
2. 6
3. -3

12. The oxidation number of Sulphur in Na₂S₄O₆ is

1. 1.5
2. 2.5
3. 3
4. 2

13. In oxygen di fluoride the oxidation number of oxygen is

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

14. Which of the following is a redox reaction?

1. NaCl + KNO₃ -> NaNO₃ + KCl
2. CaC₂O₄ + 2HCl -> CaCl₂ + H₂C₂O₄
3. Mg (OH)₂ + 2NH₄Cl -> MgCl₂ + 2NH₄OH
4. Zn + 2AgCN -> 2Ag + Zn (CN)₂

15. Which reaction is not feasible?

1. 2KI + Br₂ -> 2KBr + I₂
2. 2KBr + I₂ -> 2KI + Br₂
3. 2KBr + Cl₂ -> 2KCl+Br₂
4. 2H₂O + 2F₂ -> 4HF+O₂