An inorganic Lewis acid `(X)` shows the following reactions :
(a) It fumes in moist air.
(b) The intensity of fumes increase when a rod dippod in `NH_(4) OH` is brought near it.
( c) To an aqueous solution of `(X)`, addition of `NH_(4)Cl` and `NH_(4)OH` gives a precipitate which dissolves in `NaOH` solution.
(d) An acidic solution of `(X)` does not give a precipitate with `H_(2) S`.
Identify `(X)` and gives chemical reactions for `(a)` to `(d)`.

Options

A. `FeCl_(3)`
B. `AlCl_(3)`
C. `SnCl_(2)`
D. `ZnCl_(2)`

Explanation

`(X) is `AlCl_(3)`
`AlCl_(3)underset(moisture)(+3H_(2)O)toAl(OH)_(2)darrunderset(fumes)(+3HCl)`
`AlCl_(3)+3NH_(4)OHtoAl(OH)_(3)darr+3NH_(4)Cl`
`Al(OH)_(3)+NaOHtoNaAlO_(2)+H_(2)O`
`AlCl_(3)+H_(2)S+H^(+)to"No ppt."`
Hence,(B) is the correct answer.