⚛️ Physics · Kinetic Theory · NEET & JEE

At the same temperature, the ratio of rms speeds of helium (M = 4) to methane (M = 16) is:

Answer: 2 : 1.

A 1 : 2
B 4 : 1
C 2 : 1
D 1 : 4

Correct answer: C. 2 : 1

Explanation: v<sub>rms</sub> &prop; 1/√M, so ratio = √(16/4) = 2 : 1.

Not all gas molecules move at the same speed - the Maxwell-Boltzmann distribution shows the spread, with the most probable speed v_p slightly less than the average v_avg, which is slightly less than the root-mean-square speed v_rms 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.

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At the same temperature, the ratio of rms speeds of helium (M = 4) to methane (M = 16) is:

Concept context

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