10-minute Quiz : Chapter 32 Electrolysis

In the electrolysis of molten potassium chloride, the potassium ions are attracted to the

• A. positive electrode where they undergo oxidation.
• B. negative electrode where they undergo oxidation.
• C. positive electrode where they undergo reduction.
• D. negative electrode where they undergo reduction.

The diagram shows a set-up used in an electrolysis experiment. All the electrodes are made of platinum. Which of the combinations about the substances formed at each electrode is correct?

• A
• B
• C
• D

Consider the set-up as shown. No current flows when the sodium bromide is in the solid state. The ammeter shows a non-zero reading when the solid sodium bromide is heated to molten. Which of the following correctly explains the observations?

• A. A high temperature is needed to initiate the electrolysis.
• B. The ionic bonds between sodium ions and bromide ions are strong.
• C. The oxidation of bromide ions produces electrons.
• D. When sodium bromide is melted, the ions become mobile.

Consider the set-up as shown for performing electrolysis of copper(II) sulphate solution. Which of the following statements is INCORRECT?

• A. Cu²⁺(aq) ions are produced at the anode.

• B. Copper is deposited on the cathode.
• C. Reduction occurs at the positive electrode.
• D. The colour intensity of the copper(II) sulphate solution remains unchanged.

When concentrated potassium iodide solution with a few drops of phenolphthalein is electrolysed, what will be the colour observed at each electrode?

• A. A brown colour is observed at the cathode and a pink colour is observed at the anode.
• B. A red colour is observed at the cathode and a pink colour is observed at the anode.
• C. A pink colour is observed at the cathode and a brown colour is observed at the anode.
• D. A brown colour is observed at the anode and there is no colour change at the cathode.

The electrolysis of substance X produces gases at both electrodes. Which of the following substances can X be?

• A. Silver nitrate solution
• B. Potassium chloride solution
• C. Molten sodium hydroxide
• D. Molten copper(II) chloride

Refer to the electrolytic cell as shown. Which of the graphs correctly shows the change in mass of the graphite electrode A during electrolysis?

• A
• B
• C
• D

Which of the following equations represents the overall reaction occurred when concentrated sodium chloride solution is electrolysed using a mercury cathode and a graphite anode?

• A. 2NaCl(aq) + 2H₂O(l) → H₂(g) + Cl₂(g) + 2Na⁺(aq) + 2OH⁻(aq)
• B. 2Hg(l) + 2Na⁺(aq) + 2Cl⁻(aq) → 2Na/Hg(l) + Cl₂(g)
• C. 2H⁺(aq) + 2Cl⁻(aq) → H₂(g) + Cl₂(g)
• D. 2H₂O(l) → 2H₂(g) + O₂(g)

On which of the iron nails will a layer of copper by plated?

• A
• B
• C
• D

Consider the following statements and choose the best answer:

1st statement

During the electrolysis of concentrated sodium chloride solution using inert electrodes, hydrogen is produced at the anode and chlorine is produced at the cathode.

2nd statement

Ions are attracted to the oppositely charged electrodes.

• A. Both statements are true and the 2nd statement is a correct explanation of the 1st statement.
• B. Both statements are true but the 2nd statement is NOT a correct explanation of the 1st statement.
• C. The 1st statement is false but the 2nd statement is true.
• D. Both statements are false.