JEE Main 2020 — Chemistry Physical Chemistry

2020integermedium

The elevation of boiling point of $0.10m$ aqueous ${\mathrm{CrCl}}_{3}.{\mathrm{xNH}}_{3}$ solution is two times that of $0.05m$ aqueous ${\mathrm{CaCl}}_{2}$ solution. The value of $x$ is $\ldots \ldots \ldots \ldots ..$

[Assume $100%$ ionisation of the complex and ${\mathrm{CaCl}}_{2},$ coordination number of $\mathrm{Cr}$ as $6,$ and that all ${\mathrm{NH}}_{3}$ molecules are present inside the coordination sphere]

Official previous-year question

Held on 6 Sept 2020 · Verified 6 Jul 2026.

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Solution

$0.05m$ aqueous ${\mathrm{CaCl}}_{2}$ $=0.15$ molal solution of non electrolyte

Since the elevation in boiling point is double so the molality of given solution of complex $=0.3m$

Hence the complex must be producing three ions in the solution, so its formula $=[\mathrm{Cr}{({\mathrm{NH}}_{3})}_{5}\mathrm{Cl}]{\mathrm{Cl}}_{2}$

SO $X=5$

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JEE Main Physical Chemistry in other years

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JEE Main 2020 — Chemistry Physical Chemistry

2020integermedium

[Assume $100%$ ionisation of the complex and ${\mathrm{CaCl}}_{2},$ coordination number of $\mathrm{Cr}$ as $6,$ and that all ${\mathrm{NH}}_{3}$ molecules are present inside the coordination sphere]

Official previous-year question

Held on 6 Sept 2020 · Verified 6 Jul 2026.

Did you get this right?

Solution

$0.05m$ aqueous ${\mathrm{CaCl}}_{2}$ $=0.15$ molal solution of non electrolyte

Since the elevation in boiling point is double so the molality of given solution of complex $=0.3m$

Hence the complex must be producing three ions in the solution, so its formula $=[\mathrm{Cr}{({\mathrm{NH}}_{3})}_{5}\mathrm{Cl}]{\mathrm{Cl}}_{2}$

SO $X=5$

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 2020 — Chemistry Physical Chemistry

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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 2020 — 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