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Friday, 9 October

NEET UG 2020 · Physics · Question 155

NEET 2020 Physics, question 155

Question 155 of the NEET 2020 paper (code E1) is a Physics question from Kinetic Theory. Its idea, Mean Free Path, was asked twice, in 2020 and 2026, across NEET 2017–2026. The NTA final answer key gives option 2.

Updated 2026-10-08

Q155 · Physics

The mean free path for a gas, with molecular diameter d and number density n can be expressed as :

  1. 112 nπd\frac{1}{\sqrt{2}\,n\pi d}
  2. 212 nπd2\frac{1}{\sqrt{2}\,n\pi d^2}Official answer
  3. 312 n2πd2\frac{1}{\sqrt{2}\,n^2\pi d^2}
  4. 412 n2π2d2\frac{1}{\sqrt{2}\,n^2\pi^2 d^2}

Official answer: option 2 · NTA final answer key

Same idea

Mean Free Path, in other papers

NEET asked this idea twice, in 2020 and 2026. The other question below.

  • 2026 Q2The mean free path of molecules in an ideal gas A is half that of another ideal gas B. The diameter of the spherical molecules of gas A is…Numerical · Medium

Mean Free Path: every question and how it was framed

The chapter

Kinetic Theory in ten years of NEET

14 questions from 2017–2026, asked in 10 of 10 papers, about 1.4 a paper. Kinetic Theory of Gases alone had 14.

Chapter analysisStudy this chapterPractise this chapter

Kinetic Theory: questions per paper

0241’171’181’193’201’211’221’231’242’252’26