The speed of sound in an ideal gas at a given temperature $$T$$ is $$v$$. The rms speed of gas molecules at that temperature is $$v_{\text {rms }}$$. The ratio of the velocities $$v$$ and $$v_{\text {rms }}$$ for helium and oxygen gases are $$X$$ and $$X^{\prime}$$ respectively. Then, $$\frac{X}{X^{\prime}}$$ is equal to

Pressure of ideal gas at constant volume is proportional to .........

"Heat cannot be flow itself from a body at lower temperature to a body at higher temperature". This statement corresponds to

Which of the following curves represent the variation of coefficient of volume expansion of an ideal gas at constant pressure?