10-minute Quiz : Chapter 30 Redox reactions

Which of the following processes does NOT involve a redox reaction?

• A. Burning of a candle
• B. Rusting of iron
• C. Neutralizing excess acid in the stomach by taking antacids
• D. Dissolving zinc in dilute sulphuric acid

What is the oxidation number of Cr in Cr(CO)₆?

• A. 0
• B. +2
• C. +3
• D. +6

Consider the following reaction.

3Br₂ + 6CO₃²⁻ + 3H₂O → 5Br⁻ + BrO₃⁻ + 6HCO₃⁻

Which of the following statements concerning the reaction is correct?

• A. Bromine is oxidized and carbonate ion is reduced.
• B. Bromine is reduced and water is oxidized.
• C. Bromine is neither reduced nor oxidized.
• D. Bromine is reduced and oxidized at the same time.

1 mol of N₂H₄ loses 10 mol of electrons to form a new compound X. It is known that all the nitrogen appears in X and there is no change in oxidation number of hydrogen. What is the oxidation number of nitrogen in X?

• A. +3
• B. +5
• C. −1
• D. −3

Consider the following reaction.

2Ag + 2H₂SO₄ → Ag₂SO₄ + 2H₂O + SO₂

The sulphuric acid acts as

(1) an oxidizing agent.

(2) a reducing agent.

(3) a dehydrating agent.

• A. (1) only
• B. (2) only
• C. (1) and (3) only
• D. (2) and (3) only

Equal volumes of 1 M KMnO₄(aq) and 1 M K₂Cr₂O₇(aq) are allowed to react with excess Fe²⁺(aq) under acidic conditions in two beakers respectively. Which of the following statements is/are correct?

(1) The amount of Fe²⁺(aq) reacted will be larger with KMnO₄(aq).

(2) The amount of Fe²⁺(aq) reacted will be larger with K₂Cr₂O₇(aq).

(3) A colour change is observed in both beakers.

• A. (1) only
• B. (2) only
• C. (1) and (3) only
• D. (2) and (3) only

In an alkaline medium, potassium permanganate solution is mixed with potassium iodide solution. Permanganate ions are reduced to manganese(IV) oxide. The following half equation represents the oxidation of iodide.

I⁻ + 6OH⁻ → IO₃⁻ + 3H₂O + 6e⁻

How many moles of KMnO₄ will be reduced by one mole of KI in the alkaline medium?

• A. 1
• B. 2
• C. 3
• D. 6

Colourless silver nitrate solution slowly turns blue when copper chips are added to it. The observation is due to

• A. the dissolution of copper atoms.
• B. the reduction of silver ions.
• C. the reduction of copper(II) ions.
• D. the oxidation of copper atoms.

Substance P can decolourize bromine water. Which of the following compounds may P be?

(1) Potassium sulphite solution

(2) Iron(III) sulphate solution

(3) Cyclohexene

• A. (1) and (2) only
• B. (1) and (3) only
• C. (2) and (3) only
• D. (1), (2) and (3)

Which of the following elements does NOT show the tendency to undergo disproportionation reactions?

• A. Oxygen
• B. Chlorine
• C. Fluorine
• D. Manganese