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⚛️ Physics  ·  Kinetic Theory  ·  NEET & JEE

By what factor must the absolute temperature of an ideal gas be increased to double the rms speed of its molecules?

Answer: 4.

  • A 2
  • B 4
  • C √2
  • D 8

Correct answer: B. 4

Explanation: rms speed is proportional to √T, so doubling the speed requires the absolute temperature to become 4 times its original value.

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 →