At 298 K, the limiting molar conductivity of a weak monobasic acid is $4 \times 10^{2} \mathrm{~S} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}$. At 298 K, for an aqueous solution of the acid the degree of dissociation of $\boldsymbol{\alpha}$ and the molar conductivity is $\mathbf{y} \times 10^{2} \mathrm{~S} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}$. At 298 K, upon 20 times dilution with water, the molar conductivity of the solution becomes $3 \mathbf{y} \times 10^{2} \mathrm{~S} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}$. The value of $\mathbf{y}$ is ____.

JEE Advanced · 2021 · 03 Oct 2021 · Paper 2 · Redox Reactions and Electrochemistry

At 298 K, the limiting molar conductivity of a weak monobasic acid is

4 \times 1 0^{2} S cm^{2} mol^{- 1}

. At 298 K, for an aqueous solution of the acid the degree of dissociation of

α

and the molar conductivity is

y \times 1 0^{2} S cm^{2} mol^{- 1}

. At 298 K, upon 20 times dilution with water, the molar conductivity of the solution becomes

3 y \times 1 0^{2} S cm^{2} mol^{- 1}

.

The value of

y

is ____.

Answer: 0.86

Solution

From the previous question, we found

y = 44/51

. Calculating:

y = 44 \div 51 = 0.8627...

, which rounds to 0.86.

JEE Advanced · 2021 · 03 Oct 2021 · Paper 2 · Numerical answer

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