10th class Chemistry, Chapter 16: Electrochemistry MCQs

1. The oxidation number of Mn in K₂MnO₄:

1. (A) +7
2. (B) +5
3. (C) +6 ✓
4. (D) -6

2. Which element in the reaction 4HBr + MnO₂ → MnBr₂ + Br₂ + 2H₂O is being reduced?

1. (A) Br
2. (B) Mn ✓
3. (C) H
4. (D) Both Mn and H

3. During electrolysis of dilute solution of H₂SO₄, using Pt electrodes, which process takes place at the cathode?

1. (A) Reduction ✓
2. (B) Neither oxidation nor reduction
3. (C) Oxidation
4. (D) First oxidation and then reduction

4. Which product you will get at the anode when an aqueous solution of CuSO₄ is electrolysed using copper electrodes?

1. (A) Cu
2. (B) O₂
3. (C) H₂
4. (D) No product, instead copper metal will go into the solution as Cu²⁺. ✓

5. Which of the following statements is NOT correct about Zn-Cu electrochemical cell?

1. (A) Anode is negatively charged
2. (B) Reduction occurs at anode ✓
3. (C) Cathode is positively charged
4. (D) Reduction occurs at cathode

6. Which product will be obtained at the anode when a concentrated solution of NaCl will be electrolysed?

1. (A) Cl₂ ✓
2. (B) O₂
3. (C) More O₂ and less Cl₂
4. (D) More Cl₂ and less O₂

7. When a dilute aqueous solution of ZnCl₂ is electrolysed which product you will get at the cathode?

1. (A) H₂ ✓
2. (B) Zn
3. (C) O₂
4. (D) Zn and O₂

8. What is produced at the cathode in hydrogen-oxygen fuel cell?

1. (A) H⁺
2. (B) O²⁻
3. (C) H₂O
4. (D) OH⁻ ✓

9. Which of the following metals is highest in the electrochemical series?

1. (A) Tin
2. (B) Iron
3. (C) Magnesium ✓
4. (D) Zinc

10. The oxidation number is the:

1. (A) real charge on an atom
2. (B) number of neutrons
3. (C) apparent charge on an atom in a compound or an ion ✓
4. (D) number of electrons in the nucleus

11. The oxidation number of an atom in a free element is:

1. (A) +1
2. (B) -1
3. (C) 0 ✓
4. (D) +2

12. The oxidation number of oxygen in ozone (O₃) is:

1. (A) -2
2. (B) 0 ✓
3. (C) +2
4. (D) -1

13. For monoatomic ions, the oxidation number is equal to the:

1. (A) number of protons
2. (B) charge on the ion ✓
3. (C) atomic mass
4. (D) group number

14. Fluorine, being the most electronegative atom, is always given the oxidation number:

1. (A) -1 ✓
2. (B) +1
3. (C) 0
4. (D) -2

15. The oxidation number of hydrogen in sodium hydride (NaH) is:

1. (A) +1
2. (B) 0
3. (C) +2
4. (D) -1 ✓

16. The oxidation number of oxygen in most of its compounds is:

1. (A) +2
2. (B) -2 ✓
3. (C) -1
4. (D) 0

17. The sum of the oxidation numbers of all atoms in a neutral compound is:

1. (A) +1
2. (B) -1
3. (C) zero ✓
4. (D) equal to the group number

18. The oxidation number of sulphur in SO₄²⁻ is:

1. (A) +2
2. (B) +4
3. (C) +8
4. (D) +6 ✓

19. The oxidation number of manganese in KMnO₄ is:

1. (A) +7 ✓
2. (B) +2
3. (C) +4
4. (D) +6

20. The oxidation number of Fe in Fe₂O₃ is:

1. (A) +2
2. (B) +3 ✓
3. (C) +6
4. (D) -3