Which graph represents the variation of $PV$ with $V$ for a fixed mass of an ideal gas at constant temperature?

For the equation $\beta = - \frac{1}{V} \left( \frac{dV}{dP} \right)$, identify the correct graph of $\beta$ versus $P$ for an ideal gas at constant temperature.

Statement-$1$: Internal energy of a gas $U = nC_VT$ is due to the random motion of gas molecules.
Statement-$2$: $A$ container is moving with speed $v$. It is suddenly stopped by a force,and the temperature of the gas increases.

An insulated container contains a monoatomic gas of molar mass $M$. The container is moving with velocity $V$. If it is stopped suddenly, the change in temperature of the gas is ($R$ = gas constant).

According to the kinetic theory of gases,which one of the following statements is wrong?

At the top of a mountain,a thermometer reads $7^{\circ}C$ and a barometer reads $70 \ cm-Hg$. At the base of the mountain,the thermometer reads $27^{\circ}C$ and the barometer reads $76 \ cm-Hg$. The ratio of the density of air at the top of the mountain to the density of air at the base is: