JEE Main · 2019 · Shift-ImediumEC-111

Consider the statements S1 and S2: S1: Conductivity always increases with decrease in the concentration of electrolyte.…

Electrochemistry · Class 12 · JEE Main Previous Year Question

Question

Consider the statements S1 and S2:

S1: Conductivity always increases with decrease in the concentration of electrolyte. S2: Molar conductivity always increases with decrease in the concentration of electrolyte.

The correct option among the following:

Options
  1. a

    S1 is wrong and S2 is correct

  2. b

    S1 is correct and S2 is wrong

  3. c

    Both S1 and S2 are correct

  4. d

    Both S1 and S2 are wrong

Correct Answera

S1 is wrong and S2 is correct

Detailed Solution

Strategy: Define and distinguish specific conductan\ce (κ\kappa) and molar conductivity (Λm\Lambda_m). Recall how each changes when concentration decreases (dilution).

Analysis:

  • S1 (Conductan\ce): Decrease in concentration (dilution) means there are fewer ions in a fixed volume (like 1 cm31 \text{ cm}^3). Therefore, κ\kappa decreases. Statement S1 is false.
  • S2 (Molar Conductivity): Λm\Lambda_m accounts for the total conductivity of 1 mole of electrolyte. Even if κ\kappa drops, the effect of redu\ced inter-ionic interferen\ce (strong) or increased dissociation (weak) makes the total molar conductan\ce increase. Statement S2 is correct.

Answer: (a) S1 is wrong and S2 is correct\boxed{\text{Answer: (a) S1 is wrong and S2 is correct}}

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