Easy MCQ +4 / -1 PYQ · JEE Mains 2021

The number of molecules in one litre of an ideal gas at 300 K and 2 atmospheric pressure with mean kinetic energy 2 $\times$ 10$-$9 J per molecules is :

  1. A 0.75 $\times$ 10<sup>11</sup>
  2. B 3 $\times$ 10<sup>11</sup>
  3. C 1.5 $\times$ 10<sup>11</sup> Correct answer
  4. D 6 $\times$ 10<sup>11</sup>

Solution

KE = ${3 \over 2}kT$<br><br>PV = ${N \over {{N_A}}}RT$<br><br>N = ${{PV} \over {kT}}$<br><br>= N = 1.5 $\times$ 10<sup>11</sup>

About this question

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

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