JEE Main 2017ChemistrySolutionsMediumMCQ

JEE Main 2017 — Solutions Question with Solution

JEE Main 2017 (02 Apr)

Question

The freezing point of benzene decreases by 0.45°C on adding 0.2 g of acetic acid to 20 g of benzene. If acetic acid associates to form a dimer in benzene, then what is the percentage association of acetic acid in benzene?

Kf for benzene=5.12 K kg mol-1 

Choose an option

Show full solutionCorrect option: C
Correct answer
C94.6%

Step-by-step explanation

2CH3COOH⇌CH3COOH21-αα2

i=1-α2

ΔTf=i×Kf×m

0.45=i×5.12×0.2×100060×20

i=0.527=1-α2 

⇒α=0.946 or 94.6%

Practice this on the real CBT interface

Solve this JEE Main question (and the rest of the Solutions chapter) on PrepSharp's TCS iON-style CBT player — with timer, bookmarks and session analytics.

Solve interactively →

About this question

This is a previous-year question from JEE Main 2017, 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.