For an ideal gas obeying Boyle's Law,which of the following is correct? ($K$ is a constant)

What is the molar volume of an ideal gas at $STP$ (or $NTP$) and $SATP$?

The density of a gas $A$ is three times that of a gas $B$. If the molecular mass of $A$ is $M$,the molecular mass of $B$ is:

$A$ vacuum vessel of volume $1 \, dm^3$ is evacuated at a constant temperature of $-23 \, ^\circ C$ until the pressure drops to $7.6 \times 10^{-5} \, torr$. What is the number of molecules remaining in the vessel?

The densities of $2$ gases are in the ratio $1:2$ and their temperatures are in the ratio $2:1$. What is the ratio of their respective pressures?

State the combined gas law and the ideal gas equation.