JEE Main 2021ChemistrySolutionsEasyNumerical

JEE Main 2021 — Solutions Question with Solution

JEE Main 2021 (26 Feb Shift 2)

Question

When 12.2 g of benzoic acid is dissolved in 100 g of water, the freezing point of solution was found to be -0.93 °CKfH2O=1.86 K kg mol-1. The number n of benzoic acid molecules associated (assuming 100% association) is _.

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Show full solutionCorrect answer: 2
Correct answer
2

Step-by-step explanation

ΔTf=i×kf×m

0--0.93=i×1.86×12.2122×100×1000

i=0.931.86=0.5

i=1+1n-1α

12=1+1n-1×1

n=2

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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.