Weight of Chlorine = 71g

Weight of metal chloride = 111g

Weight of metal = 40g

$\frac{{\mathrm{W}}_{\mathrm{M}}}{{\mathrm{W}}_{\mathrm{Cl}}}=\frac{{\mathrm{E}}_{\mathrm{M}}}{{\mathrm{E}}_{\mathrm{Cl}}}$

$\frac{40}{71}=\frac{{\mathrm{E}}_{\mathrm{M}}}{35.5}$=20

40g metal displaces 2 grams of H₂   E_M = 20

40g metal displaces 2 g equivalent of H₂ then valency of the metal is 2

AW = EW $\times$ 2

AW = 20  $\times$2 = 40