`BeCl_(2)` being a salt of a weak base , `Be(OH)_(2)` and a strong acid , HCl undergoes hydrolysis by water to form HCl which fumes in air. `BaCl_(2)` , on the other hand , being a salt of a strong base , `Ba(OH)_(2)` and strong acid , HCl does not undergo hydrolysis by water to form HCl and hence does not fume in air .
`BeCl_(2) + 2H_(2)O to Be(OH)_(2) + 2HCl , BaCl_(2) + 2H_(2)O to Ba(OH)_(2) + 2HCl`
