JEE Main 2019 — Solutions Question with Solution
From: JEE Main 2019 (Online) 12th January Evening Slot
Question
Molecules of benzoic acid (C6H5COOH) dimerise in benzene. 'w' g of the acid dissolved in 30 g of benzene shows a depression in freezing point equal to 2K. If the percentage association of the acid to form dimmer in the solution is 80, then w is – (Its given that Kf = 5 K kg mol–1, Molar mass of benzoic acid = 122 g mol–1)
Choose an option
Show full solutionCorrect option: D
Correct answer
D2.4 g
Step-by-step explanation
We know,
Tf = i Kf
i = 1 +
Here Benzoic acid dimerise, so value of n = 2
i = 1 + 0.8
= 1 0.4
= 0.6
2 = 0.6 5
w = 2.44 g
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