JEE Main 2023 — Chemistry Physical Chemistry

2023integermedium

$20%$ of acetic acid is dissociated when its $5g$ is added to $500\mathrm{mL}$ of water. The depression in freezing point of such water is $_____\times {10}^{-3}C\circ$ . Atomic mass of $C,H$ and $O$ are $12,1$ and $16$ a.m.u. respectively.

[Given : Molal depression constant and density of water are $1.86K\mathrm{kg}{\mathrm{mol}}^{-1}$ and $1g{\mathrm{cm}}^{-3}$ respectively.

Official previous-year question

Held on 1 Feb 2023 · Verified 6 Jul 2026.

Did you get this right?

Solution

Van't Hoff factor (i) for dissociation of acetic acid can be written as follows,

$i=1+(n-1)\alpha$

$n=$ Number of ions

$\alpha =$ Degree of dissociation

$(i=1+0.2(2-1)=1.2$

${\Delta T}_{f}={\mathrm{iK}}_{f}m {\Delta T}_{f}=\mathrm{Depression}\mathrm{in}\mathrm{freezing}\mathrm{point} {K}_{f}=\mathrm{Molar}\mathrm{depression}\mathrm{constant} m=\mathrm{molality}$

${\Delta T}_{f}=1.2\times 1.86\times \frac{5\times 1000}{60\times 500}$

${\Delta T}_{f}=0.372$

$\Delta {T}_{f}=372\times {10}^{-3}$

Your note

JEE Main Physical Chemistry in other years

Physical Chemistry 2026 Physical Chemistry 2025 Physical Chemistry 2024 Physical Chemistry 2022 Physical Chemistry 2021 Physical Chemistry 2020 Physical Chemistry 2019 Physical Chemistry 2018 Physical Chemistry 2017 Physical Chemistry 2016 Physical Chemistry 2015 Physical Chemistry 2014

Keep practicing Physical Chemistry

Work through every JEE Main Physical Chemistry PYQ, year by year.

Browse all Chemistry topics

JEE Main 2023 — Chemistry Physical Chemistry

2023integermedium

[Given : Molal depression constant and density of water are $1.86K\mathrm{kg}{\mathrm{mol}}^{-1}$ and $1g{\mathrm{cm}}^{-3}$ respectively.

Official previous-year question

Held on 1 Feb 2023 · Verified 6 Jul 2026.

Did you get this right?

Solution

Van't Hoff factor (i) for dissociation of acetic acid can be written as follows,

$i=1+(n-1)\alpha$

$n=$ Number of ions

$\alpha =$ Degree of dissociation

$(i=1+0.2(2-1)=1.2$

${\Delta T}_{f}={\mathrm{iK}}_{f}m {\Delta T}_{f}=\mathrm{Depression}\mathrm{in}\mathrm{freezing}\mathrm{point} {K}_{f}=\mathrm{Molar}\mathrm{depression}\mathrm{constant} m=\mathrm{molality}$

${\Delta T}_{f}=1.2\times 1.86\times \frac{5\times 1000}{60\times 500}$

${\Delta T}_{f}=0.372$

$\Delta {T}_{f}=372\times {10}^{-3}$

Your note

JEE Main Physical Chemistry in other years

Keep practicing Physical Chemistry

Work through every JEE Main Physical Chemistry PYQ, year by year.

Browse all Chemistry topics

JEE Main 2023 — Chemistry Physical Chemistry

Did you get this right?

Solution

Your note

JEE Main Physical Chemistry in other years

More JEE Main Physical Chemistry questions

Other Chemistry topics for JEE Main

Organic Chemistry

Inorganic Chemistry

Keep practicing Physical Chemistry

JEE Main 2023 — Chemistry Physical Chemistry

Did you get this right?

Solution

Your note

JEE Main Physical Chemistry in other years

More JEE Main Physical Chemistry questions

Other Chemistry topics for JEE Main

Organic Chemistry

Inorganic Chemistry

Keep practicing Physical Chemistry