Thermodynamics JEE Mains Questions - List Of Most Asked Questions With Solutions

NTA will shortly release the JEE Main Syllabus 2025 at jeemain.nta.ac.in. Last Year, the complete syllabus of JEE Main underwent some major changes. According to the latest syllabus guidelines, the weightage of Physics has dropped to 22.5%. Due to these changes in the syllabus, certain shifts in chapter-wise weightage have been observed. Thermodynamics are among such topics. It’s among the least weightage topics in JEE Main Physics Syllabus 2025. This chapter holds 1.39% weightage in the whole syllabus.

• Thermodynamics is a part of the General Physics section, and every year around 2-3 questions are asked from this chapter. Due to the drop in weightage, you can expect 1-2 questions in JEE Main 2025.
• Thermodynamics in JEE Mains Physics Syllabus 2025 covers all the basic concepts on units and measurements, fundamentals of units, dimensions etc.

Aspirants consider Thermodynamics as one of the Easiest Chapters in Physics for JEE Main 2025. Even though this chapter has the least weightage in the syllabus, to develop a strong foundation in physics, this particular chapter plays a pivotal role. Hence the candidates need to develop a clear understanding of this chapter. The list of most asked questions from this chapter will help the students with their preparation.

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Thermodynamics JEE Mains Questions -

List Of Most Asked Questions With Solutions

In the (JEE) Main, the topic of Physics and Measurement often features questions that have appeared multiple times in previous years. Many questions in this section are either repeated or follow similar patterns, with only minor changes, such as different numerical values or slight modifications in wording.Certain questions have been repeated as many as five times.

Here are some of the most frequently asked and repeated questions:

Question: The enthalpy change for the combustion of methane is -890 kJ/mol. What is the heat released when 3 mol of methane is burnt? (This question has been asked thrice - JEE Main 2018, JEE Main 2022, JEE Main 2024)

· A) 2670 kJ

· B) 1780 kJ

· C) 1335 kJ

· D) 3560 kJ

Solution: The heat released for 1 mol of methane is 890 kJ. For 3 mol, it will be 3 x 890 = 2670 kJ. Correct answer is A.

Year: 2024

Question: For an ideal gas, which of the following is correct? (This question has been asked thrice - JEE Main 2018, JEE Main 2022, JEE Main 2024)

· A) ΔH = ΔU + nRΔT

· B) ΔH = ΔU - nRΔT

· C) ΔH = ΔU + pΔV

· D) ΔH = ΔU

Solution: For an ideal gas, ΔH = ΔU + pΔV. Correct answer is C.

Year: 2022

Question: If ΔG for a reaction is negative, what can be inferred about the reaction? (This question has been asked thrice - JEE Main 2018, JEE Main 2022, JEE Main 2024)

· A) The reaction is spontaneous

· B) The reaction is non-spontaneous

· C) The reaction is at equilibrium

· D) The reaction will stop

Solution: A negative ΔG indicates a spontaneous reaction. Correct answer is A.

Year: 2021

Question: The entropy change for a reversible isothermal process is: (This question has been asked thrice - JEE Main 2018, JEE Main 2022, JEE Main 2024)

· A) Zero

· B) Positive

· C) Negative

· D) Undefined

Solution: For a reversible isothermal process, the entropy change is zero. Correct answer is A.

Year: 2020

Question: The internal energy of an ideal gas depends on: (This question has been asked thrice - JEE Main 2018, JEE Main 2022, JEE Main 2024)

· A) Volume

· B) Temperature

· C) Pressure

· D) All of the above

Solution: The internal energy of an ideal gas depends only on temperature. Correct answer is B.

Year: 2019

Question: For a reaction to be spontaneous at all temperatures, which of the following conditions must be satisfied? (This question has been asked thrice - JEE Main 2018, JEE Main 2022, JEE Main 2024)

· A) ΔH < 0 and ΔS > 0

· B) ΔH > 0 and ΔS > 0

· C) ΔH > 0 and ΔS < 0

· D) ΔH < 0 and ΔS < 0

Solution: For a reaction to be spontaneous at all temperatures, ΔH must be negative and ΔS must be positive. Correct answer is A.

Year: 2018

Question: Which law of thermodynamics defines the absolute entropy of a substance? (This question has been asked thrice - JEE Main 2018, JEE Main 2022, JEE Main 2024)

· A) Zeroth law

· B) First law

· C) Second law

· D) Third law

Solution: The third law of thermodynamics defines the absolute entropy of a substance. Correct answer is D.

Year: 2017

Question: The heat capacity at constant volume for an ideal gas is: (This question has been asked thrice - JEE Main 2018, JEE Main 2022, JEE Main 2024)

· A) Cv = R

· B) Cv = 3/2 R

· C) Cv = Cp

· D) Cv = 5/2 R

Solution: For a monatomic ideal gas, the heat capacity at constant volume is Cv = 3/2 R. Correct answer is B.

Year: 2016

Question: Which of the following reactions is endothermic? (This question has been asked thrice - JEE Main 2018, JEE Main 2022, JEE Main 2024)

· A) Combustion of methane

· B) Photosynthesis

· C) Respiration

· D) Neutralization of HCl and NaOH

Solution: Photosynthesis is an endothermic reaction. Correct answer is B.

Year: 2015

Question: Which of the following statements is correct according to the second law of thermodynamics? (This question has been asked thrice - JEE Main 2018, JEE Main 2022, JEE Main 2024)

· A) The entropy of the universe is always increasing

· B) The entropy of an isolated system is constant

· C) The energy of the universe is constant

· D) Work is a state function

Solution: According to the second law of thermodynamics, the entropy of the universe is always increasing. Correct answer is A.

Year: 2014