In Boyle's law, what remains constant?

Explain why the pressure inside a tyre increases when a vehicle moves for a long period of time.

$A$ sample of oxygen gas and a sample of hydrogen gas both have the same mass,same volume,and the same pressure. The ratio of their absolute temperatures is (Molecular weights of $O_2$ and $H_2$ are $32$ and $2$ respectively).

The expansion of an ideal gas of mass $m$ at a constant pressure $P$ is given by the straight line $D$. Then the expansion of the same ideal gas of mass $2m$ at a pressure $P/2$ is given by the straight line

$A$ vessel containing $5 \, L$ of a gas at $0.8 \, Pa$ pressure is connected to an evacuated vessel of volume $3 \, L$. The resultant pressure inside will be ...... $Pa$ (assuming the whole system to be isolated).

$A$ tyre of a vehicle is filled with air having pressure $270 \text{ kPa}$ at $27^{\circ}C$. The air pressure in the tyre when the temperature increases to $37^{\circ}C$ is (in $\text{ kPa}$)