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Electrolytic and galvanic cells; electrodes and potentials: NEET MCQs with answers

90 questions on this topic of Redox Reactions and Electrochemistry (NEET 2027 syllabus). Here are 12; tap one to see its answer and explanation.

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easy

1. Standard electrode potential of SHE:

  1. 1.0V
  2. 0.0V
  3. -1.0V
  4. 0.5V
Show answer and explanation

Answer: (B) 0.0V

SHE = 0.00 V by definition. All others measured relative to it.

Quick tip: SHE = 0V. +E° = better oxidizing agent. -E° = better reducing agent.

NCERT Class 12, Chapter 3, page 77

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2. Standard reduction potentials: E°(Mg²⁺/Mg) = -2.37 V and E°(Cu²⁺/Cu) = 0.34 V. The standard emf of the galvanic cell made from these electrodes is:

  1. 0.34 V
  2. 2.03 V
  3. 2.71 V
  4. 2.37 V
Show answer and explanation

Answer: (C) 2.71 V

The electrode with the higher reduction potential (Cu²⁺/Cu) is the cathode. E°cell = E°cathode − E°anode = 0.34 − (-2.37) = 2.71 V.

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3. A current of 10 A is passed through a solution of Zn²⁺ ions for 10 minutes. The mass of zinc deposited (molar mass 65.4 g/mol; F = 96500 C/mol) is:

  1. 2.03 g
  2. 1.02 g
  3. 0.0339 g
  4. 4.07 g
Show answer and explanation

Answer: (A) 2.03 g

Charge Q = 10 × 600 = 6000 C. Mass = QM/(nF) = 6000 × 65.4/(2 × 96500) = 2.03 g.

easy

4. In a Daniell cell (Zn | Zn²⁺(aq) || Cu²⁺(aq) | Cu), an opposing external potential (E_ext) is applied across the two electrodes. Which of the following statements is correct when E_ext > 1.1 V?

  1. Electrons flow from Zn to Cu and current flows from Cu to Zn.
  2. Zinc dissolves at the zinc electrode and copper deposits at the copper electrode.
  3. No chemical reaction occurs and current ceases to flow.
  4. Electrons flow from Cu to Zn and zinc deposits at the zinc electrode.
Show answer and explanation

Answer: (D) Electrons flow from Cu to Zn and zinc deposits at the zinc electrode.

When E_ext > 1.1 V, the cell functions as an electrolytic cell. The direction of current is reversed: electrons flow from Cu to Zn, copper dissolves at the copper electrode, and zinc deposits at the zinc electrode.

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5. Standard reduction potentials: E°(Al³⁺/Al) = -1.66 V and E°(Ag⁺/Ag) = 0.8 V. The standard emf of the galvanic cell made from these electrodes is:

  1. 2.46 V
  2. 0.8 V
  3. 0.86 V
  4. 1.66 V
Show answer and explanation

Answer: (A) 2.46 V

The electrode with the higher reduction potential (Ag⁺/Ag) is the cathode. E°cell = E°cathode − E°anode = 0.8 − (-1.66) = 2.46 V.

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6. Standard reduction potentials: E°(Ni²⁺/Ni) = -0.25 V and E°(Pb²⁺/Pb) = -0.13 V. The standard emf of the galvanic cell made from these electrodes is:

  1. 0.13 V
  2. 0.38 V
  3. 0.12 V
  4. 0.25 V
Show answer and explanation

Answer: (C) 0.12 V

The electrode with the higher reduction potential (Pb²⁺/Pb) is the cathode. E°cell = E°cathode − E°anode = -0.13 − (-0.25) = 0.12 V.

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7. A current of 10 A is passed through a solution of Ag⁺ ions for 60 minutes. The mass of silver deposited (molar mass 108 g/mol; F = 96500 C/mol) is:

  1. 0.672 g
  2. 20.1 g
  3. 80.6 g
  4. 40.3 g
Show answer and explanation

Answer: (D) 40.3 g

Charge Q = 10 × 3600 = 36000 C. Mass = QM/(nF) = 36000 × 108/(1 × 96500) = 40.3 g.

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8. Given reduction potentials E°cathode = 0.8 V and E°anode = -0.2 V, the standard EMF of the cell is:

  1. 0.6 V
  2. 1 V
  3. -1 V
  4. 0.5 V
Show answer and explanation

Answer: (B) 1 V

E°cell = E°cathode − E°anode = 0.8 − (-0.2) = 1 V.

Quick tip: When both values are reduction potentials: cathode minus anode.

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9. Given reduction potentials E°cathode = 1.5 V and E°anode = -0.3 V, the standard EMF of the cell is:

  1. -1.8 V
  2. 1.8 V
  3. 1.2 V
  4. 0.9 V
Show answer and explanation

Answer: (B) 1.8 V

E°cell = E°cathode − E°anode = 1.5 − (-0.3) = 1.8 V.

Quick tip: When both values are reduction potentials: cathode minus anode.

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10. A current of 2 A is passed through a solution of Zn²⁺ ions for 30 minutes. The mass of zinc deposited (molar mass 65.4 g/mol; F = 96500 C/mol) is:

  1. 1.22 g
  2. 0.61 g
  3. 2.44 g
  4. 0.0203 g
Show answer and explanation

Answer: (A) 1.22 g

Charge Q = 2 × 1800 = 3600 C. Mass = QM/(nF) = 3600 × 65.4/(2 × 96500) = 1.22 g.

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11. Standard reduction potentials: E°(Zn²⁺/Zn) = -0.76 V and E°(Pb²⁺/Pb) = -0.13 V. The standard emf of the galvanic cell made from these electrodes is:

  1. 0.13 V
  2. 0.76 V
  3. 0.63 V
  4. 0.89 V
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Answer: (C) 0.63 V

The electrode with the higher reduction potential (Pb²⁺/Pb) is the cathode. E°cell = E°cathode − E°anode = -0.13 − (-0.76) = 0.63 V.

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12. A galvanic cell has E°cathode = 0.7 V and E°anode = -0.1 V, both quoted as reduction potentials. The standard cell potential is:

  1. 0.8 V
  2. 0.6 V
  3. -0.8 V
  4. 0.4 V
Show answer and explanation

Answer: (A) 0.8 V

E°cell = E°cathode − E°anode = 0.7 − (-0.1) = 0.8 V.

Quick tip: When both values are reduction potentials: cathode minus anode.

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