A metal X is more easily oxidized than metal Y. If X and Y form a galvanic cell, which metal acts as the anode?
Answer: A
The metal that is more easily oxidized (more reactive) acts as the anode. Metal X, being more reactive, loses electrons and acts as the anode (negative electrode).
Q.2Medium
The standard cell potential for a reaction is -0.5 V. What can be concluded about this reaction?
Answer: D
A negative E° (E°cell < 0) indicates a non-spontaneous reaction under standard conditions. ΔG° = -nFE°, so negative E° gives positive ΔG°.
Q.3Medium
In the Daniel cell, the half-cell potentials are: Cu²⁺ + 2e⁻ → Cu, E° = +0.34 V and Zn²⁺ + 2e⁻ → Zn, E° = -0.76 V. Calculate E°cell:
Answer: C
E°cell = E°cathode - E°anode = 0.34 - (-0.76) = 0.34 + 0.76 = 1.10 V. Cu²⁺ is reduced (cathode) and Zn is oxidized (anode).
Q.4Medium
Which of the following has the highest reduction potential?
Answer: A
Fluorine has the highest reduction potential among the halogens, approximately +2.87 V. Reduction potentials decrease down the halogen group: F₂ > Cl₂ > Br₂ > I₂.
Q.5Medium
What is the relationship between ΔG° and E°cell?
Answer: B
The Gibbs free energy change is related to cell potential by ΔG° = -nFE°cell, where n is the number of electrons transferred, F is Faraday's constant, and E° is the standard cell potential.
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Q.6Medium
In electroplating of iron with copper, the cathode is made of:
Answer: B
In electroplating iron with copper, iron (the object to be plated) acts as the cathode where Cu²⁺ ions are reduced and deposit as copper metal. The anode is made of copper.
Q.7Medium
The conductivity of a solution decreases with dilution because:
Answer: C
Upon dilution, the number of ions per unit volume decreases (concentration effect) and ionic mobility also increases slightly due to reduced ion-ion interactions, but overall conductivity decreases because the decrease in ion concentration dominates.
Q.8Medium
What is the relationship between ΔG° and E°cell at 25°C?
Answer: A
The fundamental relationship is ΔG° = -nFE°cell, where n is number of electrons, F is Faraday constant (96485 C/mol), and E°cell is standard cell potential.
Q.9Medium
A cell has E°cell = +0.34 V. Which statement is correct?
Answer: C
When E°cell > 0, the cell reaction is spontaneous. ΔG° = -nFE°cell is negative, indicating spontaneity.
Q.10Medium
The molar conductivity of an electrolyte increases upon dilution because:
Answer: B
Upon dilution, the degree of ionization increases due to reduced ion-ion interactions (interionic forces), leading to more free ions and higher molar conductivity.
Q.11Medium
During the electrolysis of molten NaCl, the cathode product is:
Answer: B
In molten NaCl electrolysis, Na⁺ is reduced at cathode to Na metal. Cl⁻ is oxidized to Cl₂ at anode. Water is absent, so no oxygen evolution.
Q.12Medium
Which of the following solutions has the highest conductivity?
Answer: B
HCl is a strong electrolyte with complete ionization. NaCl is also strong but HCl has higher molar conductivity. CH₃COOH and NH₃ are weak electrolytes with low ionization.
Q.13Medium
The equivalent conductivity of a strong electrolyte at infinite dilution (Λ∞) for HCl is approximately:
Answer: A
Λ∞ for HCl ≈ 426 S·cm²·mol⁻¹ (sum of Λ∞H⁺ ≈ 350 and Λ∞Cl⁻ ≈ 76). This is higher than monovalent salts due to high mobility of H⁺.
Q.14Medium
In a concentration cell, the EMF depends on:
Answer: B
In a concentration cell, E°cell = 0, so EMF = (RT/nF)ln(C₁/C₂), depending only on the concentration ratio, temperature, and number of electrons transferred.
Q.15Medium
Calculate the number of Faradays required to deposit 3.2 g of Cu (atomic mass 64) from CuSO₄ solution:
Answer: A
Cu²⁺ + 2e⁻ → Cu. Moles of Cu = 3.642 = 0.05 mol. Charge = 0.05 × 2 = 0.1 F (since 1 F = 1 mole of electrons).
Q.16Medium
In the electrolysis of dilute H₂SO₄ with inert electrodes, the cathode reaction is:
Answer: A
In dilute H₂SO₄, H⁺ is preferentially reduced over water at the cathode (less negative reduction potential), producing H₂ gas.
Q.17Medium
The Nernst equation relates cell potential to which of the following?
Answer: C
The Nernst equation: E = E° - (RT/nF)ln(Q) shows that cell potential depends on both temperature (T) and concentration (through Q, the reaction quotient).
Q.18Medium
In the electrolysis of aqueous KCl solution with inert electrodes, which gas is produced at the cathode?
Answer: B
At the cathode in KCl solution, H⁺ ions (from water) are preferentially reduced to H₂ gas because water reduction potential (-0.83 V) is higher than K⁺ reduction potential (-2.93 V).
Q.19Medium
The cell potential at 25°C for the reaction: Cu(s) + 2Ag⁺(aq) → Cu²⁺(aq) + 2Ag(s) is 0.46 V. Calculate ΔG°:
Answer: B
ΔG° = -nFE°cell = -2 × 96485 × 0.46 = -88,766 J/mol ≈ -88.7 kJ/mol. The negative value confirms spontaneity.
Q.20Medium
Which metal cannot be obtained by electrolysis of its aqueous salt solution?
Answer: C
Sodium has a very negative reduction potential (-2.71 V). Water is preferentially reduced instead. Sodium is obtained by electrolysis of molten NaCl. Copper, silver, and gold can be obtained from aqueous solutions.
