Chemistry carries the highest scoring potential in JEE for anyone who keeps the three branches separate in revision. This set covers physical chemistry numericals, organic reaction mechanisms and named reactions, and inorganic chemistry including periodic trends, chemical bonding and coordination compounds. Organic questions show the mechanism arrow by arrow, so the reasoning transfers to reactions you have not seen before.
Which of the following is a primary cell (non-rechargeable)?
Answer: B
A dry cell or Leclanche cell is a primary cell that cannot be recharged. Lead-acid and Ni-Cd are secondary cells; Li-ion is rechargeable.
Q.322Easy
In electroplating, the object to be plated is connected to which terminal?
Answer: B
In electroplating, the object to be plated is made the cathode (negative terminal) where reduction occurs, causing metal deposition.
Q.323Medium
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.324Medium
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.325Medium
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.326Medium
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.327Medium
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.328Medium
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.329Medium
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.330Medium
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.331Hard
The standard reduction potential for Zn²⁺/Zn is -0.76 V and for Cu²⁺/Cu is +0.34 V. For the cell Zn-Cu, E°cell is:
Answer: B
E°cell = E°cathode - E°anode = (+0.34) - (-0.76) = +1.10 V. Cu²⁺ is reduced (cathode), Zn is oxidized (anode).
Q.332Hard
An electrochemical cell requires 193,700 C of charge to deposit 19.6 g of a metal X. The valency of metal X is:
Answer: B
Charge = 193,700 C; moles of electrons = 193,96700,500 = 2. If 19.6 g = ? mol; then valency n = (moles of e⁻)/(moles of metal). Assuming atomic mass from calculation gives valency = 3 (like Al).
Q.333Hard
At 25°C, for a cell reaction: Zn(s) + 2Ag⁺(aq) → Zn²⁺(aq) + 2Ag(s), if [Zn²⁺] = 1 M and [Ag⁺] = 0.1 M, and E°cell = 1.56 V, the Ecell is approximately:
The conductivity of a solution containing 0.1 M NaCl is 1.29 S·m⁻¹. The molar conductivity is:
Answer: A
Λm = κ/C, where κ = 1.29 S·m⁻¹ = 0.0129 S·cm⁻¹ and C = 0.1 M. Λm = 0.00129.1 = 0.129 S·cm²·mol⁻¹ = 12.9 S·cm²·mol⁻¹.
Q.335Medium
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.336Easy
In a galvanic cell, oxidation occurs at which electrode?
Answer: B
In a galvanic cell, oxidation occurs at the anode. The anode is the negative electrode where electrons are released and the species loses electrons.
Q.337Easy
The Faraday constant (F) is approximately equal to:
Answer: A
Faraday constant (F) = 96485 Coulombs per mole of electrons. This represents the charge carried by one mole of electrons.
Q.338Easy
Which statement is correct regarding electrode potentials?
Answer: B
By international convention, the standard reduction potential of H⁺/H₂ couple is taken as 0.00 V at 25°C. This serves as the reference electrode for all other electrode potentials.
Q.339Easy
For a spontaneous electrochemical cell, the cell potential (E°cell) should be:
Answer: C
For a spontaneous cell reaction, E°cell > 0 (positive). When E°cell is negative, the reaction is non-spontaneous. E°cell = E°cathode - E°anode.
Q.340Medium
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).
