Chemistry Questions and Answers – Electrolytic Cells and Electrolysis

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This set of Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Electrolytic Cells and Electrolysis”.

1. The electrolyte in electrolysis is always in molten or liquid state.
a) True
b) False
View Answer

Answer: a
Explanation: Electrolysis is a process of passing a direct current through the electrodes to achieve a chemical reaction. It is not possible to achieve a chemical reaction when the chosen electrolyte is in a solid-state.
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2. What is the composition of aqua regia?
a) 1:3 of HCl and HNO3
b) 1:3 of HNO3 and HCl
c) 1:3 of HCl and H2SO4
d) 1:3 of H2SO4 and HCl
View Answer

Answer: b
Explanation: Aqua regia also known as royal water is a yellow-orange mixture of concentrated nitric acid and hydrochloric acid in the ratio 1:3. It is used by an alchemist to dissolve noble metals like gold and silver.

3. What is the preferred electrode when it is not allowed to take part in the chemical reaction?
a) Gold
b) Silver
c) Copper
d) Graphite
View Answer

Answer: d
Explanation: Electrodes which do not take part in the chemical reaction during electrolysis are known as inert electrodes. Gold, silver and graphite do not take part in the process, but graphite is preferred because gold and silver electrodes are expensive.
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4. What is the product formed at the cathode in the electrolysis of molten NaCl?
a) Chlorine gas
b) Sodium metal
c) Hydrogen gas
d) Oxygen gas
View Answer

Answer: b
Explanation: In the electrolysis of NaCl, if the electrolyte is molten NaCl, then the only ions formed after dissociation are Na+ and Cl ions. The cathode being a negatively charged electrode attracts the positive Na+ ions and neutralizes it to form Sodium metal.

5. What is the product formed at the cathode in the electrolysis of aqueous Na2SO4?
a) Sodium metal
b) Oxygen gas
c) Hydrogen gas
d) Sulphur
View Answer

Answer: c
Explanation: Na2SO4 dissociates into Na+ and SO42- ions in the electrolysis of aqueous Na2SO4. Na+ has much lower reduction potential than water and hence Na+ ions are not reduced at the cathode. Instead, reduction of water occurs giving out hydrogen gas at the cathode.
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6. What is the product formed at the cathode in the electrolysis of aqueous CuSO4?
a) Copper metal
b) Oxygen gas
c) Hydrogen gas
d) Sulphur
View Answer

Answer: a
Explanation: In the electrolysis of aqueous CuSO4, Cu2+, SO42+, H+ and OH are the ions formed after dissociation. Copper ions have much higher reduction potential than water. Hence, these ions are easily reduced and deposited as Cu at the cathode.

7. In electroplating, the metal is dissolved from the cathode and plated on the anode.
a) True
b) False
View Answer

Answer: b
Explanation: Electroplating is a process that uses direct electric current to carry metal ions from anode and carry them through the electrolyte containing the metal ion to the cathode to get a coherent metal coating.
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8. What is the electrolyte used in the electroplating of gold?
a) Molten gold
b) [AgCN2]
c) AuCN
d) AuCl3
View Answer

Answer: c
Explanation: The electrolyte in electrolysis should contain the metal to be coated, gold in this case. AuCN is used because it is exceptionally stable and doesn’t resist the flow of Au+ ions from anode to cathode.

9. What are the two electrodes used in Daniell cell?
a) Pt and Cu
b) Al and Zn
c) Al and Pt
d) Zn and Cu
View Answer

Answer: d
Explanation: The two electrodes that are used in a Daniell cell are zinc (as anode) and copper (as cathode) electrodes which are dipped in a solution containing its own ions, generally zinc sulphate and copper sulphate.
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10. The voltage of the electrochemical cell depends on the distance between the two electrodes.
a) True
b) False
View Answer

Answer: a
Explanation: Yes, the distance between the electrodes is directly proportional to the resistance between them. As the distance between the two electrodes increases, the resistance offered by the electrolyte increases and therefore reduces the voltage between them.

Sanfoundry Global Education & Learning Series – Chemistry – Class 12.

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