Question

In the kinetic theory of gases, which of the these statements is/are true?

(i) The pressure of a gas is proportional to the mean speed of the molecules.
(ii) The root mean square speed of the molecules is proportional to the pressure.
(iii) The rate of diffusion is proportional to the mean speed of the molecules.
(iv) The mean translational kinetic energy of a gas is proportional to its kelvin temperature.

• A. (ii) and (iii) only
• B. (i), (ii) and (iv) only
• C. (i) and (iii) only
• D. (iii) and (iv) only

Answer 1

The correct option is D (iii) and (iv) only

Pressure is proportional to the square of velocity (whether RMS or mean or most probable, just the constant of proportionality changes).
Hence i and ii are false.
Rate of diffusion is proportional to the mean speed, (this is true)
The average kinetic energy is proportional to temperature in the kelvin scale.
iii and iv are true.
Hence option D is correct.