What is the compressibility factor of an ideal gas?

Calculate the number of moles of the gas having volume $2.5 \ L$ at $300 \ K$ and $4.5 \ atm$? $(R=0.0821 \ atm \ dm^3 \ K^{-1} \ mol^{-1})$

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 $mole$)? $(R=8.314 \ J \ K^{-1} \ mol^{-1})$

At a temperature of $18^{\circ}C$ and a pressure of $765 \, torr$,the weight of $1.299 \, L$ of a gas is $2.71 \, g$. Calculate the molar mass of the gas at $STP$.

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

The temperature of a flask is increased from $27\,^{\circ}C$ to $277\,^{\circ}C$. If $0.1\,dm^{3}$ of gas bubbles out from the flask at $277\,^{\circ}C$,calculate the volume of the flask. (in $,dm^{3}$)