Medium MCQ +4 / -1 PYQ · JEE Mains 2021

Calculate the value of mean free path ($\lambda$) for oxygen molecules at temperature 27$^\circ$C and pressure 1.01 $\times$ 105 Pa. Assume the molecular diameter 0.3 nm and the gas is ideal. (k = 1.38 $\times$ 10$-$23 JK$-$1)

  1. A 32 nm
  2. B 58 nm
  3. C 86 nm
  4. D 102 nm Correct answer

Solution

${I_{mean}} = {{RT} \over {\sqrt 2 \pi {d^2}{N_A}P}}$<br><br>$$ = {{1.38 \times 300 \times {{10}^{ - 23}}} \over {\sqrt 2 \times 3.14 \times {{(0.3 \times {{10}^{ - 9}})}^2} \times 1.01 \times {{10}^5}}}$$<br><br>$= 102 \times {10^{ - 9}}$ m<br><br>$= 102$ nm

About this question

Subject: Physics · Chapter: Thermodynamics · Topic: Zeroth and First Law

This question is part of PrepWiser's free JEE Main question bank. 271 more solved questions on Thermodynamics are available — start with the harder ones if your accuracy is >70%.

Drill 25 more like these. Every day. Free.

PrepWiser turns these solved questions into a daily practice loop. Chapter-wise drills, full mocks, AI doubt chat. No auto-renew.

Start free →