The depression in freezing point observed for a formic acid solution of concentration $0.5\ \mathrm{mL\,L^{-1}}$ is $0.0405^\circ$C. Density of formic acid is $1.05\ \mathrm{g\,mL^{-1}}$. The Van't Hoff factor of the formic acid solution is nearly : (Given for water $k_f=1.86\ \mathrm{k\,kg\,mol^{-1}}$)

JEE Main 2022 · ChemistryMultiple choiceSingle correctMediumCalculation

JEE Main 25 July 2022, Shift 1, Chemistry Q63

Question 63 of 90 in this shift, Chemistry question 3 of 30, Section A.

The depression in freezing point observed for a formic acid solution of concentration

0.5\ \mathrm{mL\,L^{-1}}

0.0405^\circ

C. Density of formic acid is

1.05\ \mathrm{g\,mL^{-1}}

. The Van't Hoff factor of the formic acid solution is nearly : (Given for water

k_f=1.86\ \mathrm{k\,kg\,mol^{-1}}

)

(1) $0.8$
(2) $1.1$
(3) $1.9$ Official answer
(4) $2.4$

Official answer

Option 3

NTA final key (2022 Session 2).

Chapter: Solutions
Topic: Colligative Properties
Idea tested: Van't Hoff Factor (i)

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Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 42 of the 174 JEE Main shifts held from 2017 to 2026.