The combination of plots which does not represent isothermal expansion of an ideal gas is $(A)$ ![JEE Main 2019 Chemistry, Thermodynamics (C) — question figure 1](https://prepforbharat.s3.ap-south-1.amazonaws.com/exam/615f0e999476412f48314daf/Chemistry/images/Thermodynamics_C/648b5a67417cc3fb48d6693a/question_1__q_648b5a67417cc3fb48d6693a__cdn-question-pool.getmarks.app__1102d293-2946-4257-98ce-e970539b2883-image__cf8810d9e7_final_ppt_sync.png) $(B)$ ![JEE Main 2019 Chemistry, Thermodynamics (C) — question figure 2](https://prepforbharat.s3.ap-south-1.amazonaws.com/exam/615f0e999476412f48314daf/Chemistry/images/Thermodynamics_C/648b5a67417cc3fb48d6693a/question_2__q_648b5a67417cc3fb48d6693a__cdn-question-pool.getmarks.app__5ae9c384-6cb9-4ea3-b1c2-32d55c7eda55-image__fa4971a274_final_ppt_sync.png) $(C)$ ![JEE Main 2019 Chemistry, Thermodynamics (C) — question figure 3](https://prepforbharat.s3.ap-south-1.amazonaws.com/exam/615f0e999476412f48314daf/Chemistry/images/Thermodynamics_C/648b5a67417cc3fb48d6693a/question_3__q_648b5a67417cc3fb48d6693a__cdn-question-pool.getmarks.app__e39874e8-3e73-4fa0-a9cf-58d7a11f6774-image__757bcf7d48_final_ppt_sync.png) $(D)$ ![JEE Main 2019 Chemistry, Thermodynamics (C) — question figure 4](https://prepforbharat.s3.ap-south-1.amazonaws.com/exam/615f0e999476412f48314daf/Chemistry/images/Thermodynamics_C/648b5a67417cc3fb48d6693a/question_4__q_648b5a67417cc3fb48d6693a__cdn-question-pool.getmarks.app__3b813919-9505-47be-8a4d-13f37c9529c3-image__75170c7e7b_final_ppt_sync.png)

JEE Main 2019 — Chemistry Physical Chemistry

2019mcqmedium

The combination of plots which does not represent isothermal expansion of an ideal gas is

$(A)$ JEE Main 2019 Chemistry, Thermodynamics (C) — question figure 1

$(B)$ JEE Main 2019 Chemistry, Thermodynamics (C) — question figure 2

$(C)$ JEE Main 2019 Chemistry, Thermodynamics (C) — question figure 3

$(D)$ JEE Main 2019 Chemistry, Thermodynamics (C) — question figure 4

Official previous-year question

Held on 12 Jan 2019 · Verified 6 Jul 2026.

Options

A
$(A)$ and $(D)$
B
$(B)$ and $(C)$
C
$(B)$ and $(D)$
D
$(A)$ and $(C)$

Did you get this right?

Solution

JEE Main 2019 Chemistry, Thermodynamics (C) — solution figure 1

$\mathrm{PV}=$ constant (isothermal expansion)

$P\propto \frac{1}{V}$ . The graph will be a straight line, $y=\mathrm{mx}+c$ . So, the above graph is correct.

JEE Main 2019 Chemistry, Thermodynamics (C) — solution figure 2

$\mathrm{PV}=$ constant (isothermal expansion)

On increasing or decreasing $P$ , $\mathrm{PV}$ becomes constant. So, the above graph is correct.

$(A, C)$ graphs are correct.

JEE Main 2019 Chemistry, Thermodynamics (C) — solution figure 3

$\mathrm{PV}=$ constant (isothermal expansion)

$P\propto \frac{1}{V}$ . The graph will be a straight line, $y=\mathrm{mx}+c$ . So, the above graph is incorrect.

JEE Main 2019 Chemistry, Thermodynamics (C) — solution figure 4

$\Delta U={\mathrm{nC}}_{v}\mathrm{dT}$

and for isothermal process, $\Delta U=0.$ So, the above graph is incorrect.

Options $B,D$ are incorrect.

Your note

JEE Main Physical Chemistry in other years

Physical Chemistry 2026 Physical Chemistry 2025 Physical Chemistry 2024 Physical Chemistry 2023 Physical Chemistry 2022 Physical Chemistry 2021 Physical Chemistry 2020 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 2019 — Chemistry Physical Chemistry

2019mcqmedium

The combination of plots which does not represent isothermal expansion of an ideal gas is

$(A)$ JEE Main 2019 Chemistry, Thermodynamics (C) — question figure 1

$(B)$ JEE Main 2019 Chemistry, Thermodynamics (C) — question figure 2

$(C)$ JEE Main 2019 Chemistry, Thermodynamics (C) — question figure 3

$(D)$ JEE Main 2019 Chemistry, Thermodynamics (C) — question figure 4

Official previous-year question

Held on 12 Jan 2019 · Verified 6 Jul 2026.

Options

A
$(A)$ and $(D)$
B
$(B)$ and $(C)$
C
$(B)$ and $(D)$
D
$(A)$ and $(C)$

Did you get this right?

Solution

JEE Main 2019 Chemistry, Thermodynamics (C) — solution figure 1

$\mathrm{PV}=$ constant (isothermal expansion)

$P\propto \frac{1}{V}$ . The graph will be a straight line, $y=\mathrm{mx}+c$ . So, the above graph is correct.

JEE Main 2019 Chemistry, Thermodynamics (C) — solution figure 2

$\mathrm{PV}=$ constant (isothermal expansion)

On increasing or decreasing $P$ , $\mathrm{PV}$ becomes constant. So, the above graph is correct.

$(A, C)$ graphs are correct.

JEE Main 2019 Chemistry, Thermodynamics (C) — solution figure 3

$\mathrm{PV}=$ constant (isothermal expansion)

$P\propto \frac{1}{V}$ . The graph will be a straight line, $y=\mathrm{mx}+c$ . So, the above graph is incorrect.

JEE Main 2019 Chemistry, Thermodynamics (C) — solution figure 4

$\Delta U={\mathrm{nC}}_{v}\mathrm{dT}$

and for isothermal process, $\Delta U=0.$ So, the above graph is incorrect.

Options $B,D$ are incorrect.

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 2019 — 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

JEE Main 2019 — 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