Electrochemistry NEET PYQs (Previous Year Questions)
Below are important NEET previous year questions from Electrochemistry with answers and explanations to help you understand concepts clearly.
Q1. In the electrochemical cell Zn | ZnSO4 (0.01 M) || CuSO4 (1.0 M) | Cu, the emf is E1. When the concentrations are reversed, emf becomes E2. What is the correct relation?
(NEET 2017)
- (A) E1 < E2
- (B) E1 > E2
- (C) E1 = E2
- (D) E2 = 0
Show Answer
(B)
Show Explanation
According to Nernst equation, emf decreases when reaction quotient increases. Reversing concentrations increases Q, hence E1 > E2.
Q2. The molar conductivity of 0.5 M NaCl solution having conductivity 0.144 S m−1 is:
(NEET 2016)
- (A) 2.88
- (B) 11.52
- (C) 0.086
- (D) 28.8
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(D)
Show Explanation
Λm = κ × 1000 / C = 0.144 × 1000 / 0.5 = 28.8 S cm2 mol−1.
Q3. Time required to produce 0.10 mol Cl2 during electrolysis of molten NaCl using 3 A current is:
(NEET 2016)
- (A) 55 min
- (B) 110 min
- (C) 220 min
- (D) 330 min
Show Answer
(B)
Show Explanation
0.1 mol Cl2 requires 0.2 F = 19300 C.
Time = Q/I = 19300 / 3 ≈ 110 minutes.
Q4. Zinc is coated on iron to produce galvanized iron because:
(NEET 2016)
- (A) Zinc is lighter
- (B) Zinc has lower melting point
- (C) Zinc has lower reduction potential
- (D) Zinc has higher negative reduction potential
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(D)
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Zinc has more negative reduction potential than iron, so it acts as a sacrificial anode and protects iron.
Q5. A device that converts chemical energy of fuel directly into electrical energy is called:
(NEET 2015)
- (A) Dynamo
- (B) Ni-Cd cell
- (C) Fuel cell
- (D) Electrolytic cell
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(C)
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Fuel cells convert chemical energy directly into electrical energy without combustion.
Q6. Quantity of electricity required to oxidise 0.1 mol Fe2+ to Fe3+ is:
(NEET 2014)
- (A) 96500 C
- (B) 9650 C
- (C) 96.5 C
- (D) 19300 C
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(B)
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Oxidation of 0.1 mol Fe2+ requires 0.1 F = 0.1 × 96500 = 9650 C.
Q7. Weight of silver displaced when 5600 mL of O2 is liberated at STP is:
(NEET 2014)
- (A) 5.4 g
- (B) 10.8 g
- (C) 54 g
- (D) 108 g
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(D)
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5600 mL O2 = 0.25 mol O2 = 1 F.
1 F deposits 108 g of Ag.
Q8. Degree of ionisation of NH4OH at 0.1 M if Λm = 9.54 and Λm∞ = 238 is:
(NEET 2013)
- (A) 4.008%
- (B) 40.8%
- (C) 2.08%
- (D) 20.8%
Show Answer
(A)
Show Explanation
Degree of ionisation α = Λm / Λm∞ = 9.54 / 238 ≈ 0.040 = 4.0%.
Q9. The EMF of a button cell with given half-cell potentials is:
(NEET 2013)
- (A) 0.84 V
- (B) 1.10 V
- (C) 1.34 V
- (D) 0.42 V
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(C)
Show Explanation
EMF = E°(cathode) − E°(anode).
Q10. Oxidation potential of hydrogen electrode at pH = 2 is:
(NEET 2013)
- (A) 0.118 V
- (B) 1.18 V
- (C) 0.059 V
- (D) 0.59 V
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(A)
Show Explanation
E = 0.059 × pH = 0.059 × 2 = 0.118 V.
Q11. The strongest oxidising agent is the one having:
(NEET 2012)
- (A) Lowest E°
- (B) Highest E°
- (C) Zero E°
- (D) Negative E°
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(B)
Show Explanation
Higher standard reduction potential means stronger oxidising agent.
Q12. Increase in equivalent conductance of strong electrolyte on dilution is due to:
(NEET 2010)
- (A) Increase in ions
- (B) Increase in ionic mobility
- (C) Increase in ionisation
- (D) Decrease in ions
Show Answer
(B)
Show Explanation
Strong electrolytes are already fully ionised; dilution increases mobility.
Q13. At infinite dilution, each ion contributes independently to conductance. This law is:
(NEET 2008)
- (A) Faraday’s law
- (B) Kohlrausch’s law
- (C) Ohm’s law
- (D) Nernst equation
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(B)
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This is Kohlrausch’s law of independent migration of ions.
Q14. EMF of an electrochemical cell depends on:
(NEET 1998)
- (A) Temperature
- (B) Concentration
- (C) Nature of electrodes
- (D) All of these
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(D)
Show Explanation
EMF depends on temperature, concentration, and electrode nature.
Q15. Product at anode during electrolysis of dilute H2SO4 using Pt electrode is:
(NEET 1992)
- (A) H2
- (B) O2
- (C) SO2
- (D) H2S
Show Answer
(B)
Show Explanation
Water is oxidised at the anode producing oxygen gas.
Q16. For a spontaneous electrochemical reaction, ΔG is:
- (A) Positive
- (B) Zero
- (C) Negative
- (D) Infinite
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(C)
Show Explanation
ΔG = −nFE; for spontaneous reaction ΔG is negative.
Q17. Relationship between ΔG° and E° is:
- (A) ΔG° = nFE°
- (B) ΔG° = −nFE°
- (C) ΔG° = RT ln E°
- (D) ΔG° = −RT ln E°
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(B)
Show Explanation
Standard relation: ΔG° = −nFE°.
Q18. Unit of molar conductivity is:
- (A) S m−1
- (B) S m2 mol−1
- (C) ohm cm
- (D) ohm−1
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(B)
Show Explanation
Molar conductivity = conductivity × area / mol.
Q19. In Daniell cell, oxidation occurs at:
- (A) Copper electrode
- (B) Zinc electrode
- (C) Both
- (D) Salt bridge
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(B)
Show Explanation
Zinc undergoes oxidation at the anode.
Q20. Standard hydrogen electrode has standard potential value:
- (A) 1 V
- (B) 0 V
- (C) −1 V
- (D) 0.059 V
Show Answer
(B)
Show Explanation
Standard hydrogen electrode is assigned zero potential.
👉 Also check Electrochemistry Notes