At what temperature will the volume of a gas be halved if the initial temperature is $17^{\circ}C$ and the pressure remains constant (in $^{\circ}C$)?

Two containers $A$ and $B$ contain $CO_2$ gas. Pressure, volume, and absolute temperature of the gas in $A$ are $4$ times more compared to that in $B$. If the mass of the gas in $B$ is $x \ g$, then the mass of the gas in $A$ will be:

$A$ $10.0 \, L$ flask contains $64 \, g$ of oxygen at $27^{\circ} C$. (Assume $O_2$ gas is behaving ideally). The pressure inside the flask in bar is $.....$
(Given $R = 0.0831 \, L \, bar \, K^{-1} \, mol^{-1}$)

What is the volume in $litre$ occupied by $7 \, g$ of $N_2$ gas at $27 \, ^oC$ temperature and $750 \, mm \, Hg$ pressure?

What will be the effect on the density of $0.09 \ mol$ of a gas at $300 \ K$ if its pressure is increased?

Calculate the density of $CO_2$ at $100\, ^oC$ and $800\, mm\, Hg$ of pressure in $g/L$.