Pressure of a mixture of $4 \ g$ of $O_2$ and $2 \ g$ of $H_2$ confined in a bulb of $1 \ L$ at $0^{\circ}C$ is $..... \ atm$

$A$ $100 \ L$ cylinder containing $H_2$ exerted a pressure of $4 \ atm$ at $300 \ K$. It was accidentally opened and some $H_2$ escaped. When it was closed,it exerted a pressure of $3 \ atm$ at $300 \ K$. The number of moles of $H_2$ remaining in the cylinder is equal to (Assume $H_2$ as an ideal gas; $R=$ gas constant)

$34.05 \ mL$ of phosphorus vapor weighs $0.0625 \ g$ at $546 \ ^oC$ and $0.1 \ bar$ pressure. What is the molar mass of phosphorus (in $g/mol$)?

The value of the compressibility factor for an ideal gas is ........ .

What is the density of $SO_2$ gas at $27\,^oC$ temperature and $2\, atm$ pressure in $g/L$? (Atomic weights: $S = 32, O = 16, R = 0.082\, L\, atm\, K^{-1}\, mol^{-1}$)

When an ideal gas undergoes unrestrained expansion,no cooling occurs because the molecules