Given: Weight percentage of chlorine = 71% Vapour density = 50 Vapour density is given by: Vapour density = Molecular Mass/2 Substituting the value of vapour density, we get 50 = Molecular Maas /2 Molecular Mass of metal chloride = 50 x 2 = 100 Now, Chlorine is 71% by weight or 71 g/mol. Thus, Atomic weight of metal = Molecular mass of metal chloride - Weight of chlorine = 100 - 71 = 29 g/mol Hence, option 'A' is correct.