When air is filled in a balloon, both the pressure and volume increase while the temperature remains constant. Why is Boyle's law not obeyed in this case?

$A$ 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?

An open-mouthed container is filled with air at $60^{\circ}C$. The container is heated to a temperature $T$ such that $1/4$ of the air escapes. The value of $T$ is ........ $^{\circ}C$.

Molar volume is the volume occupied by $1 \; mol$ of any (ideal) gas at standard temperature and pressure ($STP$: $1 \; atm$ pressure,$0^{\circ} C$). Show that it is $22.4 \; L$.

An insulated cylindrical vessel is fitted with an insulated piston of negligible weight and negligible thickness at the midpoint of the vessel. The cylinder contains a gas at $0^{\circ} C$. When the gas is heated to $100^{\circ} C$, the piston moves through a length of $5 \, cm$. The length of the cylindrical vessel in $cm$ is:

At constant temperature,increasing the pressure of a gas by $5\%$ will decrease its volume by ..... $\%$