NEET Thermodynamics PYQ practice sheet

7 previous-year NEET Physics questions from Thermodynamics, newest papers first. Thermodynamics carries 10 of the Physics questions in NEET 2020 to 2026, so this is a good place to test yourself after revising the chapter. Marking: +4 correct, −1 wrong.

1. 1.

   RE-NEET 2026

   In an adiabatic expansion, the temperature of one mole of an ideal monatomic gas ($\gamma = 5/3$) decreases from $60$ K to $50$ K. The work done by the gas in the process is: (Take the universal gas constant as $R = 8.3\ \mathrm{J\,mol^{-1}K^{-1}}$)

   • (A)
     $83\ \mathrm{J}$
   • (B)
     $124.5\ \mathrm{J}$
   • (C)
     $41.5\ \mathrm{J}$
   • (D)
     $166\ \mathrm{J}$
2. 2.

   RE-NEET 2026

   One mole of an ideal monatomic gas undergoes a cyclic process as shown in the figure. The total heat supplied to the gas is: Figure: a $P$-$V$ diagram ($P$ in $\mathrm{N/m^2}$, $V$ in $\mathrm{m^3}$) of a rectangular cycle: $a(V=2, P=300) \to b(V=5, P=300)$ (isobaric expansion), $b \to c(V=5, P=100)$ (isochoric pressure drop), $c \to d(V=2, P=100)$ (isobaric compression), $d \to a$ (isochoric pressure rise).

   • (A)
     $500$ J
   • (B)
     $600$ J
   • (C)
     $400$ J
   • (D)
     $800$ J
3. 3.

   NEET 2026

   An electric heater supplies heat to a system at a rate of 100 W. If the system performs work at a rate of 75 J/s, then the rate at which internal energy increases will be:

   • (A)
     100 W
   • (B)
     75 W
   • (C)
     125 W
   • (D)
     25 W
4. 4.

   NEET 2024

   A thermodynamic system is taken through the cycle $abcda$. The work done by the gas along the path $bc$ is: The cycle is drawn on a P–V diagram: $a$ (100 cm³, 100 kPa) $\to$ $b$ (400 cm³, 100 kPa) $\to$ $c$ (400 cm³, 300 kPa) $\to$ $d$ (100 cm³, 300 kPa) $\to$ $a$.

   • (A)
     –90 J
   • (B)
     –60 J
   • (C)
     30 J
   • (D)
     zero
5. 5.

   NEET 2023

   A Carnot engine has an efficiency of 50% when its source is at a temperature $327^\circ\mathrm{C}$. The temperature of the sink is :

   • (A)
     $200^\circ\mathrm{C}$
   • (B)
     $27^\circ\mathrm{C}$
   • (C)
     $15^\circ\mathrm{C}$
   • (D)
     $100^\circ\mathrm{C}$
6. 6.

   NEET 2022

   An ideal gas undergoes four different processes from the same initial state as shown in the figure below. Those processes are adiabatic, isothermal, isobaric and isochoric. The curve which represents the adiabatic process among 1, 2, 3 and 4 is: (Figure: a $P$-$V$ diagram with four curves labelled 1, 2, 3 and 4 all starting from the same initial point; curve 4 is the steepest falling curve, curve 1 is the least steep, with curves 2 and 3 of intermediate steepness, consistent with the four standard processes drawn from one common state.)

   • (A)
     4
   • (B)
     1
   • (C)
     2
   • (D)
     3
7. 7.

   NEET 2020

   Two cylinders A and B of equal capacity are connected to each other via a stop cock. A contains an ideal gas at standard temperature and pressure. B is completely evacuated. The entire system is thermally insulated. The stop cock is suddenly opened. The process is :

   • (A)
     isothermal
   • (B)
     adiabatic
   • (C)
     isochoric
   • (D)
     isobaric