Oxidation and reduction - Jamb Chemistry Past Questions and Answers

Question 6:

• JAMB 1979

The reaction of zinc with copper (ll) ions in aqueous solution can be represented as follows: Cu ²⁺(aq) +Zn (s) → Cu(s) + Zn ²⁺(aq).Which of the following is the most complete description of this reaction?

A. Cpper (ll) ions are being reduced
B. Zinc is being oxidized.
C. Copper (ll) ions and zinc are being reduced
D. Copper (ll) ions and zinc are being oxidized
E. Copper(ll) ions are being reduced and zinc oxidized

Question 7:

• JAMB 1979

The oxidation state of manganese in potassium permanganate is

A. +7
B. +5
C. +3
D. +2
E. +1

Question 8:

• JAMB 1979

Which of the following statements is true? When the potassium atom forms its ion

A. It gains one electron and becomes neutral
B. Its atomic number decreases
C. It achieves electronic configuration of orgon
D. It loses one proton
E. It loses one neutron

Question 9:

• JAMB 1979

In which of the following reactions is sulphur dioxide acting as an oxidizing agent?

A. SO ₂ + 2HNO₃ →H₂SO₄ + NO₂ + Heat
B. 2SO₂ + 2H₂O + O₂→ 2H₂SO₄
C. SO₂ + 2H₂O + CI₂→ H₂SO₄ + 2HCI
D. SO₂ + 2H₂S → 3S + 2H₂O
E. SO₂ + H₂O → H₂SO₃

Question 10:

• JAMB 1980

In which of the following is the oxidation state of oxygen different from its value in water?

A. OH^-
B. H₃O⁺
C. O^-
D. H₂O₂
E. SO₂