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⚛️ Physics  ·  Kinetic Theory  ·  NEET & JEE

The root mean square speed of gas molecules is given by:

Answer: v rms = √(3RT/M).

  • A v<sub>rms</sub> = √(2RT/M)
  • B v<sub>rms</sub> = √(3RT/M)
  • C v<sub>rms</sub> = √(8RT/πM)
  • D v<sub>rms</sub> = RT/M

Correct answer: B. v<sub>rms</sub> = √(3RT/M)

Explanation: v<sub>rms</sub> = √(3RT/M), where R is the gas constant, T is absolute temperature, and M is the molar mass.

Maxwell-Boltzmann Speed Distributionspeed (v)fraction of moleculesv_pv_avgv_rmsv_p < v_avg < v_rms always, for any gas at any temperature

Not all gas molecules move at the same speed - the Maxwell-Boltzmann distribution shows the spread, with the most probable speed vp slightly less than the average vavg, which is slightly less than the root-mean-square speed vrms used in the pressure formula.

Concept context

Kinetic theory of gases connects molecular motion to pressure and temperature, explaining gas laws, specific heats, and molecular speeds.

Read the full Kinetic Theory notes →