$A$ narrow glass tube,$80 \,cm$ long and open at both ends,is half-immersed in mercury. Now,the top of the tube is closed and it is taken out of the mercury. $A$ column of mercury $20 \,cm$ long remains in the tube. Find the atmospheric pressure.

$A$ long cylindrical pipe of radius $20 \,cm$ is closed at its upper end and has an airtight piston of negligible mass as shown. When a $50 \,kg$ mass is attached to the piston,it moves down. If the air in the enclosure is cooled from temperature $T$ to $T-\Delta T$,the piston moves back to its original position. Then $\Delta T / T$ is close to (Assuming air to be an ideal gas,$g=10 \,m/s^2$,atmospheric pressure is $10^5 \,Pa$)

The $PV$ versus $T$ graph for equal masses of $H_2, He$,and $O_2$ is shown in the figure. Choose the correct alternative:

From the following $P-T$ graph,what inference can be drawn?

At $100 \, K$ and $0.1 \, \text{atm}$ pressure, the volume of helium gas is $10 \, \text{litres}$. If volume and pressure are doubled, its temperature will change to ....... $K$.

$A$ gas at the temperature $250\,K$ is contained in a closed vessel. If the gas is heated through $1\,K,$ then the percentage increase in its pressure will be ...... $\%$