A metal chloride contains 55 . 0 % of chlorine by weight. 100mL...

Let the formula of metal chloride be ${MCl}_{x}$

Mass of $100mL$ of vapours of ${MCl}_{x}$ at STP $= 0 . 57g$

The mass of substance which occupies 22400 ml of volume at STP is molar mass(M)

$∴ \dfrac{100 \times M}{22400} = 0 . 57$

$∴$ Molar mass of ${MCl}_{x} = 127 . 68g{mol}^{– 1}$

The mass percentage of chlorine$= \dfrac{massofchlorine}{massofthecompound} \times 100$

$$ of $Cl = \dfrac{35 . 5x \times 100}{127 . 68} = 55$

$⇒ x = 2$

$∴$ Formula of metal chloride is ${MCl}_{2}$