For an ideal gas,the density of the gas is $\varrho_0$ when temperature and pressure of the gas are $T_0$ and $P_0$ respectively. When the temperature of the gas is $2 T_0$,its pressure becomes $3 P_0$. The new density will be

$A$ gas is collected over water at $25^{\circ}C$. The total pressure of the moist gas was $735 \, mm$ of mercury. If the aqueous vapour pressure at $25^{\circ}C$ is $23.8 \, mm$,then the pressure of the dry gas is..... $mm$.

The pressure of a given mass of gas at $20^{\circ}C$ is $P$. At constant volume,at what temperature in $^{\circ}C$ will the pressure of the gas become $2P$?

Column-$I$ represents gas laws and Column-$II$ represents the physical quantity which is constant for the given law. Match them correctly:

Column-$I$	Column-$II$
$(a)$ Boyle's law	$(i)$ Pressure
$(b)$ Charles's law	$(ii)$ Volume
	$(iii)$ Temperature

An oxygen cylinder of volume $30 \; L$ has an initial gauge pressure of $15 \; atm$ and a temperature of $27 \; ^{\circ}C$. After some oxygen is withdrawn from the cylinder,the gauge pressure drops to $11 \; atm$ and its temperature drops to $17 \; ^{\circ}C$. Estimate the mass (in $kg$) of oxygen taken out of the cylinder ($R = 8.31 \; J \; mol^{-1} K^{-1}$,molecular mass of $O_{2} = 32 \; u$).

The relationship between pressure and the density of a gas expressed by Boyle's law,$P = K\rho$,holds true: