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