Match List - I with List - II.
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List – I |
List – II |
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(A) \(\Lambda _m\) of \(KCl\) increases on dilution |
(I) is a linear graph |
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(B) \(\Lambda _m\) of \(CH_3COOH\) increases on dilution |
(II) is a non linear graph |
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(C) \(\Lambda _m\) of \(KCl\) versus (molarity)1/2 |
(III) due to increased degree of ionisation |
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(D) \(\Lambda _m\) of \(CH_3COOH\) versus (molarity)1/2 |
(IV) due to weakening of interionic attractions |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A)-(IV), (B)-(III), (C)-(I), (D)-(II)
Molar conductivity (Λm) increases on dilution for all electrolytes, but for different reasons. A strong electrolyte such as KCl is already fully ionised; on dilution only the interionic attractions weaken, Λm rises slowly and follows Λm = Λ°m − A c½. A weak electrolyte such as \( \ce{CH3COOH} \) ionises more and more on dilution, so Λm rises steeply, especially at low concentration.
(A) Λm of KCl increases on dilution — This matches (IV) due to weakening of interionic attractions. The ions move farther apart, are less held back by oppositely charged ions and move faster.
(B) Λm of \( \ce{CH3COOH} \) increases on dilution — This matches (III) due to increased degree of ionisation. More acetic acid molecules ionise, so the number of ions per mole rises.
(C) Λm of KCl versus (molarity)1/2 — This matches (I) is a linear graph. Λm = Λ°m − A c½ is a straight line with intercept Λ°m and slope −A.
(D) Λm of \( \ce{CH3COOH} \) versus (molarity)1/2 — This matches (II) is a non linear graph. Λm rises sharply near zero concentration, so the curve cannot be extrapolated to find Λ°m.
Shortcut: (A)-(IV) appears only in Option (2).
NCERT (2026-27 edition):
Variation of Conductivity and Molar Conductivity with Concentration – …
Note: The same/similar question has been asked in different years by NTA as per the details given below:
| 2026 | 2025 | 2024 | 2023 | 2022 |
|---|---|---|---|---|
| – | – | – | 10-06 S1 07-06 S3 | – |