JEE Main 2022 — Chemistry Physical Chemistry

2022integereasy

$4.0L$ of an ideal gas is allowed to expand isothermally into vacuum until the total volume is $20L$ . The amount of heat absorbed in this expansion is $L$ atm.

Official previous-year question

Held on 28 Jun 2022 · Verified 6 Jul 2026.

Did you get this right?

Solution

In case of expansion, work is done by system.

Now, as we know that,

$W=-{P}_{\mathrm{ext}.}\Delta V$

As the gas is expanding into vacuums which has no pressure, i.e.,

${P}_{\mathrm{ext}.}=0$

$\therefore W=0$

Hence, no work is done.

From first law of thermodynamics,

$\Delta U=q+W$

As the system is working at constant temperature, i.e., isothermally.

$\therefore \Delta U=0$

Hence $q=-W=0$

Your note

JEE Main Physical Chemistry in other years

Physical Chemistry 2026 Physical Chemistry 2025 Physical Chemistry 2024 Physical Chemistry 2023 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 2022 — Chemistry Physical Chemistry

2022integereasy

$4.0L$ of an ideal gas is allowed to expand isothermally into vacuum until the total volume is $20L$ . The amount of heat absorbed in this expansion is $L$ atm.

Official previous-year question

Held on 28 Jun 2022 · Verified 6 Jul 2026.

Did you get this right?

Solution

In case of expansion, work is done by system.

Now, as we know that,

$W=-{P}_{\mathrm{ext}.}\Delta V$

As the gas is expanding into vacuums which has no pressure, i.e.,

${P}_{\mathrm{ext}.}=0$

$\therefore W=0$

Hence, no work is done.

From first law of thermodynamics,

$\Delta U=q+W$

As the system is working at constant temperature, i.e., isothermally.

$\therefore \Delta U=0$

Hence $q=-W=0$

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 2022 — 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 2022 — 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