A gas has a compressibility factor of 0 . 5 and a molar volume of 0...

Compressibility factor $( Z )= \dfrac{{V}_{real}}{{V}_{ideal}} = 0 . 5$

${V}_{real} = 0 . 4{dm}^{3}{mol}^{- 1} = 0 . 4L / mol$

$∴ {V}_{ideal} = \dfrac{0 . 4}{0 . 5} = 0 . 8L / mol$

$∴ y = 0 . 8L / mol$

Using ideal gas equation : $PV = nRT$

$P = \dfrac{1 \times 8 \times {10}^{- 2} \times 800}{0 . 8}$

$x = 80atm$

$∴ \dfrac{x}{y} = \dfrac{80}{0 . 8} = 100$