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NEET UG 2026 · Chemistry · Question 59

NEET 2026 Chemistry, question 59

Question 59 of the NEET 2026 paper (re-exam) is a Chemistry question from Thermodynamics. Its idea, Entropy of Free Expansion, was asked only this once in NEET 2017–2026. The NTA final answer key gives option 4.

Updated 2026-10-08

Q59 · Chemistry

Two moles of an ideal gas undergo free expansion from 10 L to 100 L at 300 K. The values of ΔSsystem\Delta S_{system} and ΔSsurroundings\Delta S_{surroundings} are

(R is universal gas constant)

  1. 1ΔSsystem=0\Delta S_{system}=0; ΔSsurroundings=0\Delta S_{surroundings}=0
  2. 2ΔSsystem=4.606\Delta S_{system}=4.606 R; ΔSsurroundings=−4.606\Delta S_{surroundings}=-4.606 R
  3. 3ΔSsystem=0\Delta S_{system}=0; ΔSsurroundings=4.606\Delta S_{surroundings}=4.606 R
  4. 4ΔSsystem=4.606\Delta S_{system}=4.606 R; ΔSsurroundings=0\Delta S_{surroundings}=0Official answer

Official answer: option 4 · NTA final answer key

Same idea

The only question on Entropy of Free Expansion

No other NEET paper from 2017–2026 tested this exact idea.

Entropy of Free Expansion: every question and how it was framed

The chapter

Thermodynamics in ten years of NEET

32 questions from 2017–2026, asked in 10 of 10 papers, about 3.1 a paper. Gibbs Free Energy alone had 7.

Chapter analysisStudy this chapterPractise this chapter

Thermodynamics: questions per paper

0364’174’183’193’202’212’222’234’243’255’26