The molar conductivity of a weak electrolyte increases with dilution because:
Answer: B
At higher dilutions, weak electrolytes ionize more completely, increasing degree of ionization and thus molar conductivity
Q.91Easy
Which of the following best explains why diamond is harder than graphite?
Answer: B
Diamond has a 3D tetrahedral covalent network structure with C-C bonds in all directions, while graphite has layered structure with weak van der Waals forces between layers
Q.92Medium
For the reaction 2A(g) ⇌ B(g) + C(g), if initial pressure is 2 atm and degree of dissociation is 0.5, what is the total pressure at equilibrium?
Answer: A
Initial: 2 atm of A. At equilibrium with α = 0.5: A dissociates to (1-0.5)×2 = 1 atm, producing B and C each at 0.5 atm. Total = 1 + 0.5 + 0.5 = 2 atm × (1 + α) = 2 × 1.5 = 3 atm
Q.93Easy
Which of the following factors does NOT affect the value of the equilibrium constant Kc?
Answer: C
Kc depends only on temperature. Pressure, concentration changes, and catalysts do not alter Kc value—they shift equilibrium position but not the constant itself.
Q.94Medium
A solution contains 0.1 M weak acid HA (Ka = 1×10⁻⁵). The degree of ionization is approximately:
Answer: D
For weak acid: α = √(Ka/C) = √(1×10⁻⁵/0.1) = √(1×10⁻⁴) = 0.01 or 1%. Using exact formula: α ≈ 0.0316 (3.16%)
Q.95Hard
At 298 K, ΔG° for a reaction is -20 kJ/mol. The reaction quotient Q = 0.01 when Kp = 1000. Which statement is true?
Answer: A
ΔG° = -20 kJ/mol (negative, spontaneous). Since Q (0.01) < Kp (1000), reaction shifts forward. ΔG = ΔG° + RTlnQ = -20 + 8.314×298×ln(0.01) will be more negative, confirming forward reaction.
Q.96Easy
The molar heat capacity at constant pressure (Cp) for an ideal gas is 29 J/(mol·K). Its molar heat capacity at constant volume (Cv) is approximately:
Answer: A
Cp - Cv = R = 8.314 J/(mol·K). Therefore, Cv = 29 - 8.314 ≈ 20.7 ≈ 20.8 J/(mol·K). This indicates a diatomic gas (Cp = 27 R, Cv = 25 R).
Q.97Easy
In a first-order reaction, if the half-life is 10 minutes, the time taken for the concentration to reduce to 41th of initial value is:
Answer: B
For first-order reaction, each half-life reduces concentration by 50%. After 1st half-life (10 min): 50% remains. After 2nd half-life (20 min): 25% remains = 41th. Total time = 2 × 10 = 20 minutes.