The adjoining figure shows graphs of pressure and volume of a gas at two temperatures $T_1$ and $T_2$. Which of the following is correct?

$A$ $20 \,cm$ long tube is closed at one end. It is held vertically,and its open end is dipped in water until only half of it is outside the water surface. Consequently,water rises in it by height $h$ as shown in the figure. The value of $h$ is closest to (assume that the temperature remains constant,$P_{\text{atm}} = 10^5 \,N/m^2$,density of water $\rho = 10^3 \,kg/m^3$,and acceleration due to gravity $g = 10 \,m/s^2$): (in $,cm$)

The volume-temperature graph at atmospheric pressure for a monoatomic gas ($V$ in $m^3$,$T$ in $^{\circ}C$) is:

One mole of an ideal gas undergoes a process in which pressure $P$ varies with volume $V$ as $P = 3 - g \left(\frac{V}{V_0}\right)^2$,where $V_0$ and $g$ are constants. The maximum temperature attainable by the ideal gas during this process is ($All$ quantities are in $SI$ units and $R$ is the gas constant).

What is molar mass?

$A$ metre-long narrow bore held horizontally (and closed at one end) contains a $76 \; cm$ long mercury thread,which traps a $15 \; cm$ column of air. What happens if the tube is held vertically with the open end at the bottom?