JEE Main 2021ChemistrySolutionsEasyNumerical

JEE Main 2021 — Solutions Question with Solution

JEE Main 2021 (25 Feb Shift 2)

Question

If a compound AB dissociates to the extent of 75% in an aqueous solution, the molality of the solution which shows a 2.5 K rise in the boiling point of the solution is ___ molal. (Rounded-off to the nearest integer) Kb=0.52K kg mol-1.

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Show full solutionCorrect answer: 3
Correct answer
3

Step-by-step explanation

α=0.75,n=2

i=1-α+nα=1-0.75+2×0.75=1.75

ΔTb=ikbm

or 2.5=1.75×0.52×m

or, m=2.51.75×0.52=2.74

∴ nearest integer answer will be 3

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About this question

This is a previous-year question from JEE Main 2021, covering the Solutions chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.