$A$ sample of oxygen gas is compressed from a volume of $500 \, cc$ to $400 \, cc$ at a pressure of $2 \, atm$. If the temperature is kept constant,what pressure in $atm$ is required?

An electron tube was sealed off during manufacture at a pressure of $1.2 \times 10^{-7} \text{ mm}$ of mercury at $27^{\circ}C$. Its volume is $100 \text{ cm}^3$. The number of molecules that remain in the tube is

$A$ cylinder contains $10\, kg$ of gas at a pressure of $10^7\, N/m^2$. The quantity of gas taken out of the cylinder,if the final pressure is $2.5 \times 10^6\, N/m^2$,will be ..... $kg$ (Temperature of the gas is constant).

Equal molar amounts of $H_2$ and $He$ are placed in two separate containers of equal volume at the same temperature. Their molar masses are $2$ and $4$ respectively. If the pressure of $H_2$ gas is $4 \ atm$,what will be the pressure of $He$ gas in atmospheres?

The expansion of unit mass of a perfect gas at constant pressure is shown in the diagram. Here

$A$ $20 \,cm$ 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 $,cm$)