Chapter Exam

Chapter-2 Electrochemistry — Online MCQ Test

Q: Who developed the Nernst equation?

Answer: B. Walther Nernst — The Nernst equation was developed by German chemist Walther Nernst in 1889 to relate cell potential to concentration.

Q: Calculate the cell potential using Nernst equation at 25°C when Q = K (equilibrium state):

Answer: B. E_cell = 0 V — At equilibrium, Q = K, and the Nernst equation gives E_cell = E°_cell - (0.0592/n)log(K) = 0, since log(K) = log(K).

Q: For the reaction: Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s), if E° = 1.1 V at 25°C, the Gibbs free energy change (ΔG°) is approximately:

Answer: A. -212 kJ/mol — Using ΔG° = -nFE° = -(2)(96485)(1.1) ≈ -212 kJ/mol. The negative value confirms the reaction is spontaneous.

CHEMISTRY · Grade 12 · CBSE(NCERT)

Practice Chapter-2 Electrochemistry with a free chapter-wise online MCQ test for CBSE(NCERT) Grade 12 CHEMISTRY. This chapter covers: galvanic cells - Nernst equation - conductance - fuel cells. AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter-2 Electrochemistry — Important Questions & Answers (FAQ)

Frequently asked questions from CBSE(NCERT) Grade 12 CHEMISTRY — Chapter-2 Electrochemistry, with answers and explanations. These are sample questions; the exam has its own separate question set.

What is a galvanic cell?

A. A device that converts electrical energy into chemical energy
B. A device that converts chemical energy into electrical energy ✓
C. A device used only for electroplating
D. A device that stores only thermal energy

Answer: B. A device that converts chemical energy into electrical energy
A galvanic cell spontaneously converts chemical energy from redox reactions into electrical energy through electron flow.

Who developed the Nernst equation?

A. Michael Faraday
B. Walther Nernst ✓
C. Alessandro Volta
D. Antoine Lavoisier

Answer: B. Walther Nernst
The Nernst equation was developed by German chemist Walther Nernst in 1889 to relate cell potential to concentration.

Calculate the cell potential using Nernst equation at 25°C when Q = K (equilibrium state):

A. E_cell = 1 V
B. E_cell = 0 V ✓
C. E_cell = 0.06 V
D. E_cell = -1 V

Answer: B. E_cell = 0 V
At equilibrium, Q = K, and the Nernst equation gives E_cell = E°_cell - (0.0592/n)log(K) = 0, since log(K) = log(K).

For the reaction: Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s), if E° = 1.1 V at 25°C, the Gibbs free energy change (ΔG°) is approximately:

A. -212 kJ/mol ✓
B. -424 kJ/mol
C. +212 kJ/mol
D. +424 kJ/mol

Answer: A. -212 kJ/mol
Using ΔG° = -nFE° = -(2)(96485)(1.1) ≈ -212 kJ/mol. The negative value confirms the reaction is spontaneous.

A fuel cell has several advantages over combustion engines EXCEPT:

A. Higher efficiency (60-70% vs. 30-40%)
B. Lower operating temperatures
C. Produces only water as emission (in H₂-O₂ cells)
D. Can operate at high pressures with explosive risk comparable to petrol engines ✓

Answer: D. Can operate at high pressures with explosive risk comparable to petrol engines
While fuel cells have many advantages, hydrogen fuel cells do carry explosion risks at high pressure, which is a potential disadvantage (not an exception to advantages).