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Thermodynamics — NEET & JEE Chemistry MCQs

30 questions written by hand against the NCERT chapter. Every wrong option is explained, not just the right one.

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10/14/6easy / medium / hard
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Sample questions from this chapter

In thermodynamics, what is the system?
  1. The selected part of the universe under observation ✓
  2. Everything outside the laboratory building
  3. Only the container wall around reacting substances
  4. The system and surroundings taken together
Answer: A. The observer defines a chosen region or matter as the system; the interacting remainder is its surroundings and the separating surface is the boundary.
Why not B: Surroundings are the portion outside the selected system that can interact with it, not merely a geographic exterior.
Why not C: The wall is the boundary; the chosen contents or region constitute the system.
Why not D: System plus surroundings is called the universe.
A system absorbs 50 kJ of heat and does 20 kJ of work on the surroundings. What is ΔU?
  1. +70 kJ
  2. -70 kJ
  3. +30 kJ ✓
  4. -30 kJ
Answer: C. Heat absorbed gives q = +50 kJ, while work done by the system gives w = −20 kJ. Thus ΔU = q + w = +30 kJ; the +70 trap reverses work sign.
Why not A: This treats work done by the system as positive and adds it to absorbed heat.
Why not B: This assigns negative signs to both the absorbed heat and the system's expansion work.
Why not D: This obtains the correct magnitude but reverses the sign of q + w.
One mole of ideal gas expands reversibly and isothermally at 298 K from 10.0 L to 20.0 L. What is w? Use R = 8.314 J K^-1 mol^-1.
  1. -1.72 kJ ✓
  2. +1.72 kJ
  3. -2.48 kJ
  4. -0.693 kJ
Answer: A. wrev = −nRT ln(Vf/Vi) = −(1)(8.314)(298)ln2 = −1717 J = −1.72 kJ. The gas does maximum expansion work on its surroundings.
Why not B: This uses the correct magnitude but assigns positive work to expansion rather than compression.
Why not C: This uses −nRT and omits the logarithmic volume ratio ln 2.
Why not D: This reports −ln 2 as kilojoules without multiplying by nRT.

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Read the chapter first

Every NCERT question in this chapter is solved, free: NCERT solutions — Thermodynamics →

Other NEET Chemistry chapters

Some Basic Concepts of ChemistryStructure of AtomClassification of Elements and Periodicity in PropertiesChemical Bonding and Molecular StructureEquilibriumRedox Reactions

All 19 chapters →

Questions

How many NEET and JEE questions are there on Thermodynamics?

This chapter test has 30 questions — 10 easy, 14 medium and 6 hard — all written against the NCERT Class 11 chapter.

Is this NEET and JEE Chemistry chapter test free?

Yes. Every chapter test is free with no login, and you get your all-India rank on every one. Nothing on the site is on sale right now.

Do the questions explain the wrong options?

Yes — every distractor carries its own explanation naming the specific misconception that makes a student pick it. That is the part most question banks skip, and it is the part that changes your next attempt.