Thermodynamics JEE Main Questions 2025: Important Practice Questions with PYQs

Thermodynamics JEE Main Questions 2025: What makes Thermodynamics different from other physics topics for JEE Mains 2025 is its very high potential for students to score marks in the JEE Mains 2025 exam. Often experts recommend candidates who are preparing for the JEE Main exam to practise Thermodynamics JEE Main Questions 2025 to successfully answer all the questions from this chapter. Moreover, solving as many questions from Thermodynamics for JEE Mains 2025 can help students to prepare well for the exams. Candidates can check this article on JEE Main 2025 Questions from Thermodynamics for more detailed knowledge.

Also Read: JEE Main Previous Year Question Paper

JEE Main 2025 Thermodynamics Important Questions - Formula Based

Candidates can check the questions along with their respective answers for the following sets of formula-based questions.

Q) A system absorbs 500 J of heat and does 200 J of work on the surroundings. What is the change in the internal energy of the system?

A)                                      Δ U =  Q - W

=  500 J - 200 J

= 300 J

Q) A 2 litre container holds an ideal gas at a pressure of 1 atm and a temperature of 300 K. If the temperature is increased to 600 K while keeping the volume constant, what will be the new pressure of the gas?

A)                            P ₁ ​ / T ₁ ​ = P ₂ ​/ T ₂ ​

P ₂ = P ₁ x T ₂ / T ₁

= 1 x 600 / 300

= 2 atm

Q) For an adiabatic process, if an ideal gas undergoes a change such that the initial pressure P ₁ ​= 2 atm, volume V ₁ ​= 4L and the final volume V ₂ ​ = 8L. Given γ = 1.4, find the final pressure P ₂ ​?

A)                                                  P ₁ V ₁ ^γ = P ₂ V ₂ ^γ

2 × 41.4 = P ₂ x 81.4

P ₂ = 0.76 atm

Q) Calculate the work done by 1 mole of an ideal gas during an isothermal expansion at 300 K from an initial volume of 1 L to a final volume of 5 L

A)                                     W = nRT ln (Vf / Vi)

= (1 mol) X (8.314 J/mol K) X (300K) ln (5/1)

= 1240 J

Q) Calculate the change in entropy when 1 mole of an ideal gas expands isothermally from a volume of 10 L to 20 L at 300 K.

A)                                         ΔS = nR ln (Vf / Vi)

= (1 mol) X (8.314 J / mol K)  ln (20 / 10)

= 5.76 J / K

Q) A Carnot engine operates between a hot reservoir at 500 K and a cold reservoir at 300 K. Calculate the efficiency of the Carnot engine.

A)                                                          η  = 1 − Tc / Th

= 1 - 300 / 500

= 0.4 or 40%

Thermodynamics JEE Main Questions 2025 - Conceptual Questions

Candidates can check the questions along with their respective answers for the following sets of conceptual questions.

Q) Which of the following statements about an isothermal process is true?

A) The internal energy of the system remains constant.

B) The temperature of the system changes.

C) The work done by the system is zero.

D) The system does not exchange heat with the surroundings.

Answer : A

Q) Which law of thermodynamics states that the entropy of an isolated system always increases over time?

A) Zeroth Law

B) First Law

C) Second Law

D) Third Law

Answer : C

Q) For an ideal gas, which of the following expressions correctly describes the relationship between heat (Q), work (W), and change in internal energy (ΔU) in a cyclic process?

A) Q = W + ΔU

B) ΔU = W + Q

C) Q = ΔU

D) ΔU = 0

Answer : D

Q) The efficiency (η) of a heat engine is given by η = 1 - (T_c / T_h), where T_c is the temperature of the cold reservoir and T_h is the temperature of the hot reservoir. What type of process is this engine operating in?

A) Isothermal

B) Adiabatic

C) Isobaric

D) Isometric

Answer : A

Q) For an ideal gas undergoing an isothermal expansion, which of the following quantities remains constant?

A) Pressure

B) Volume

C) Temperature

D) Internal Energy

Answer : C

Q) In an adiabatic process, which of the following is true about the heat transfer?

A) Heat is absorbed by the system.

B) Heat is released by the system.

C) There is no heat transfer between the system and the surroundings.

D) The heat transfer is equal to the work done by the system.

Answer : C

Practise Questions for JEE Mains 2025

Candidates must solve the following practice questions for JEE Mains 2025.

Q 1) For an ideal gas undergoing an isobaric process, which of the following is true?

A) The pressure remains constant, and the volume changes.

B) The volume remains constant, and the temperature changes.

C) The temperature remains constant, and the pressure changes.

D) The internal energy remains constant.

Q 2) The change in enthalpy ΔH during a chemical reaction is equal to:

A) The heat absorbed or released at constant volume

B) The work done by the system

C) The heat absorbed or released at constant pressure

D) The change in internal energy minus the work done

Q 3) The first law of thermodynamics is a statement of the conservation of:

A) Energy

B) Momentum

C) Mass

D) Charge

Q 4) Which of the following statements is true for an isothermal process?

A) The temperature remains constant, and internal energy remains constant.

B) The temperature remains constant, and heat is transferred into or out of the system.

C) The volume remains constant, and work is done on or by the system.

D) The pressure remains constant, and the system is isolated.

Q 5) For an ideal gas, the internal energy depends only on:

A) Pressure

B) Volume

C) Temperature

D) Pressure and Volume

Q 6) The efficiency of a heat engine is given by

A) Heat Input / Work Output

B) Work Output / Heat Input

C) Heat Output / Heat Input

D) (Heat Input - Heat Output) / Heat Input

Related Reads

Candidates can check this article to solve Thermodynamics JEE Main Questions 2025 along with practising the conceptual and formula-based questions. Stay tuned to Collegedekho for the latest updates on JEE Mains 2025.