JEE Main 2020 — Chemistry Physical Chemistry

2020mcqmedium

At $35{}^{o}C,$ the vapour pressure of $C{S}_{2},$ is $512mm$ Hg and that of acetone is $144mmHg.$ A solution of $C{S}_{2}$ in acetone has a total vapour pressure of $600 mmHg$ . The false statement amongst the following is:

Official previous-year question

Held on 7 Jan 2020 · Verified 6 Jul 2026.

Options

A
Raoult's law is not obeyed by this system
B
a mixture of $100mL{CS}_{2}$ and $100mL$ acetone has a volume $<200mL$
C
${CS}_{2}$ and acetone are less attracted to each other than to themselves
D
heat must be absorbed in order to produce the solution at ${35}^{o}C$

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Solution

${\text{P}}_{ \text{observed}} =600$

${\text{P}}_{ \text{Cal}} ={\text{P}}_{\text{A}}^{\text{0}} {\text{x}}_{\text{A}} { \text{+P}}_{\text{B}}^{\text{0}} {\text{x}}_{\text{B}}$

$=512\text{x}+344-344\text{x}$

$=168\text{x}+344$

$=512$ (If $\text{x}=1$ for maximum value)

Thus, ${\text{P}}_{ \text{cal}} <{\text{P}}_{ \text{observed}}$

Thus' the process is deviated from Raoult's law, showing positive deviation from Raoult's law.

$\Delta H>0,$ i.e., is absorbed

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Options

Raoult's law is not obeyed by this system

a mixture of $100mL{CS}_{2}$ and $100mL$ acetone has a volume $<200mL$

${CS}_{2}$ and acetone are less attracted to each other than to themselves

heat must be absorbed in order to produce the solution at ${35}^{o}C$

Solution

${\text{P}}_{ \text{observed}} =600$

${\text{P}}_{ \text{Cal}} ={\text{P}}_{\text{A}}^{\text{0}} {\text{x}}_{\text{A}} { \text{+P}}_{\text{B}}^{\text{0}} {\text{x}}_{\text{B}}$

$=512\text{x}+344-344\text{x}$

$=168\text{x}+344$

$=512$ (If $\text{x}=1$ for maximum value)

Thus, ${\text{P}}_{ \text{cal}} <{\text{P}}_{ \text{observed}}$

Thus' the process is deviated from Raoult's law, showing positive deviation from Raoult's law.

$\Delta H>0,$ i.e., is absorbed

JEE Main 2020 — Chemistry Physical Chemistry

Options

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Solution

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JEE Main Physical Chemistry in other years

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JEE Main 2020 — Chemistry Physical Chemistry

Options

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