MCQ Questions

Chapter

Question No. 1

Give one word for each of these descriptions.

Answer :

a) The chemical process in which there is a transfer of electrons

b) The chemical process that occurs when the oxidation number of an atom decreases

c) The chemical process that occurs when an atom loses electrons

d) The substance that loses electrons in a redox reaction

e) The state that indicates the relative richness in electrons of a substance.

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Question No. 2

Choose the correct words: A reducing agent is (a) oxidised/reduced and (b) gains/loses electrons during a reaction. An oxidising agent is (c) oxidised/reduced and (d) gains/loses electrons during a reaction. Oxidation occurs when the atom (e) loses/gains electrons and when the oxidation number (f) increases/decreases.

Answer :

Question No. 3

Explain the meaning of oxidation numbers.

Answer :

Question No. 4

Assign oxidation numbers to the atoms in the following molecules:

Answer :

a) Iron in FeO; FeCl₃; Fe; FeBr₂

b) Copper in Cu₂O; CuCl₂; Cu; CuO; CuCl

c) Carbon in C; CO; CO₂; HCO₃⁻

d) Chlorine in Cl₂; ClF; Cl₂O; ClO₃⁻; HCl; HOCl

Question No. 5

A student prepares sulphur dioxide gas by adding concentrated sulphuric acid to copper metal filings. The balanced equation for the reaction is: Cu(s) + 2H₂SO₄(ℓ) → SO₂(g) + CuSO₄(aq) + 2H₂O(ℓ)

Answer :

a) Using oxidation numbers, identify the oxidising and reducing agents in this reaction. Show your working.

b) Write down the oxidation half-reaction.

Question No. 6

Use the following redox reactions to answer the questions: Cu(s) + 2KBr(aq) → Br₂(l) + CuBr₂(aq); CuSO₄(aq) + Zn(s) → Cu(s) + ZnSO₄(aq); Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)

Answer :

a) Identify the oxidising and reducing agents in each reaction.

b) Name the spectator ions in each reaction.

c) Describe what happens at each electrode during the reactions.