JEE Main 2023 — Chemistry Physical Chemistry

2023integermedium

The vapour pressure of $30%(w/v)$ , aqueous solution of glucose is ________ $\mathrm{mm}\mathrm{Hg}$ at ${25}^{\circ }C$ .

[Given: The density of $30%(w/v)$ , aqueous solution of glucose is $1.2g{\mathrm{cm}}^{–3}$ and vapour pressure of pure water is $24\mathrm{mm}\mathrm{Hg}$ .]

(Molar mass of glucose is $180g{\mathrm{mol}}^{–1}$ )

Official previous-year question

Held on 15 Apr 2023 · Verified 6 Jul 2026.

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Solution

To calculate the vapour pressure of the $30%$ (w/v) aqueous solution of glucose, we can use Raoult's law, which states that the vapour pressure of a component in an ideal solution is directly proportional to its mole fraction in the solution.

Weight of solution $=100\times 1.2=120\mathrm{gm}$

Weight of water $=120-30=90\mathrm{gm}$

Now using formula

$\frac{{P}_{0}-P}{P}=\frac{\mathrm{moles}\mathrm{of}glucose}{\mathrm{moles}\mathrm{of}water}$

$\frac{24-P}{P}=\frac{\frac{30}{180}}{\frac{90}{18}}=\frac{3}{90}$

$24\times 90-P\times 90=3P$

$\Rightarrow P=23.22$

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JEE Main 2023 — Chemistry Physical Chemistry

2023integermedium

The vapour pressure of $30%(w/v)$ , aqueous solution of glucose is ________ $\mathrm{mm}\mathrm{Hg}$ at ${25}^{\circ }C$ .

[Given: The density of $30%(w/v)$ , aqueous solution of glucose is $1.2g{\mathrm{cm}}^{–3}$ and vapour pressure of pure water is $24\mathrm{mm}\mathrm{Hg}$ .]

(Molar mass of glucose is $180g{\mathrm{mol}}^{–1}$ )

Official previous-year question

Held on 15 Apr 2023 · Verified 6 Jul 2026.

Did you get this right?

Solution

Weight of solution $=100\times 1.2=120\mathrm{gm}$

Weight of water $=120-30=90\mathrm{gm}$

Now using formula

$\frac{{P}_{0}-P}{P}=\frac{\mathrm{moles}\mathrm{of}glucose}{\mathrm{moles}\mathrm{of}water}$

$\frac{24-P}{P}=\frac{\frac{30}{180}}{\frac{90}{18}}=\frac{3}{90}$

$24\times 90-P\times 90=3P$

$\Rightarrow P=23.22$

Your note

JEE Main Physical Chemistry in other years

Keep practicing Physical Chemistry

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

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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

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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