What is the molar volume of an ideal gas at $27\,^oC$ and $1\, atm$ pressure in $L$?

Which one of the following is the correct $PV$ vs $P$ plot at constant temperature for an ideal gas? ($P$ and $V$ stand for pressure and volume of the gas respectively)

At a given temperature,the density of gas $x$ is twice the density of gas $y$. If the molar mass of $y$ is three times the molar mass of $x$,find the ratio of their pressures $(P_x/P_y)$.

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

$A$ and $B$ are ideal gases. At $T(K)$,$2 \ L$ of $A$ with a pressure of $1 \ bar$ is mixed with $4 \ L$ of $B$ with a pressure $p_B \ bar$ in a $100 \ L$ flask. The pressure exerted by the gaseous mixture is $0.1 \ bar$. What is the value of $p_B$ in $bar$?

Calculate the weight of $CH_4$ in a $9 \ L$ cylinder at $16 \ atm$ and $27 \ ^\circ C$ in grams.