JEE Main 2023 — Chemistry Physical Chemistry

2023integerhard

If the degree of dissociation of aqueous solution of weak monobasic acid is determined to be $0.3$ , then the observed freezing point will be _____ $%$ higher than the expected/theoretical freezing point. (Nearest integer).

Official previous-year question

Held on 10 Apr 2023 · Verified 6 Jul 2026.

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Solution

$\underset{1-\alpha }{\mathrm{HA}}\rightleftharpoons \underset{\alpha }{{H}^{+}}+\underset{\alpha }{{A}^{-}}$

Van't Hoff factor, $i=1+\alpha (n-1)$

$=1+0.3(2-1)$

$=1+0.3$

$=1.3$

$\Delta {T}_{f}$ without considering dissociation $={k}_{f}\times$ molality

$\Delta {T}_{f}$ without considering dissociation $={\mathrm{ik}}_{f}\times$ molality

$={\Delta T}_{f}^{'}$

${\Delta T}_{f}^{'}-{\Delta T}_{f}=0.3$ ( ${k}_{f}\times$ molality)

$\frac{{\Delta T}_{f}^{1}-{\Delta T}_{f}}{{\Delta T}_{f}}=\frac{0.3({k}_{f}\times \mathrm{molality})}{{k}_{f}\times \mathrm{molality}}=0.3$

$%$ value $=30$

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JEE Main Physical Chemistry in other years

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JEE Main 2023 — Chemistry Physical Chemistry

2023integerhard

Official previous-year question

Held on 10 Apr 2023 · Verified 6 Jul 2026.

Did you get this right?

Solution

$\underset{1-\alpha }{\mathrm{HA}}\rightleftharpoons \underset{\alpha }{{H}^{+}}+\underset{\alpha }{{A}^{-}}$

Van't Hoff factor, $i=1+\alpha (n-1)$

$=1+0.3(2-1)$

$=1+0.3$

$=1.3$

$\Delta {T}_{f}$ without considering dissociation $={k}_{f}\times$ molality

$\Delta {T}_{f}$ without considering dissociation $={\mathrm{ik}}_{f}\times$ molality

$={\Delta T}_{f}^{'}$

${\Delta T}_{f}^{'}-{\Delta T}_{f}=0.3$ ( ${k}_{f}\times$ molality)

$\frac{{\Delta T}_{f}^{1}-{\Delta T}_{f}}{{\Delta T}_{f}}=\frac{0.3({k}_{f}\times \mathrm{molality})}{{k}_{f}\times \mathrm{molality}}=0.3$

$%$ value $=30$

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

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Solution

Your note

JEE Main Physical Chemistry in other years

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Organic Chemistry

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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