Under which conditions will the density of a gas be maximum?

The volume-temperature graphs of a given mass of an ideal gas at different constant pressures are shown below. What is the correct order of pressures?

$A$ vessel of $120 \, mL$ capacity contains a certain amount of gas at $35^{\circ} C$ and $1.2 \, bar$ pressure. The gas is transferred to another vessel of volume $180 \, mL$ at $35^{\circ} C$. What would be its pressure?

How many moles of dioxygen are present in $8.314 \times 10^{-3} \ m^3$ of it at $318 \ K$ having pressure $3.18 \times 10^5 \ N \ m^{-2}$ (in $mole$)? $(R=8.314 \ J \ K^{-1} \ mol^{-1})$

An ideal gas with a molar mass of $40 \ g \ mol^{-1}$ has a mass of $120 \ g$. It occupies a volume of $20 \ L$ at a temperature of $400 \ K$. Using $R = 0.0821 \ L \ atm \ K^{-1} \ mol^{-1}$,the pressure of the gas is ........ $atm$.

$A$ $3.7 \ g$ sample of a gas occupies the same volume at $25 \ ^\circ C$ as $0.184 \ g$ of $H_2$ gas at $17 \ ^\circ C$ at the same pressure. The molecular weight of the gas is: