Identify the correct observation with respect to the given graphs.

A gas is present at a pressure of 2 atm . What should be the increase in pressure, so that the volume of the gas can be decreased to $\frac{1}{4}$ th of the initial volume at constant temperature?

Root mean square ( rms ) speed of $\mathrm{O}_2$ is $500 \mathrm{~m} / \mathrm{s}$ at a constant temperature. Calculate the rms speed and the average kinetic energy of $\mathrm{H}_2$ at the same temperature. (Consider, $R=8.33 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}$ )

Which of the following describes an ideal gas?

(i) The volume occupied by a gas molecule is negligible.

(ii) The collision between ideal gases are elastic.

(iii) Particles are very small compared to the distance between each other.