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)`.

Explanation

The inorganic Lewish acid (X) which fumes in moist air is probably anhydrous aluminum chloride, `AlCl_(3) `which is in accordance with the fact that its acidic solution does not give a precipitate with `H_(2)S`. Thus the given reactions of compound (X) can be written as below.
`i) AlCl_(3)+3H_(2)O rarr Al(OH)_(3)+3HCluarr`
`ii) HCl+NH_(4)OH rarr NH_(4)Cluarr +H_(2)O`
`iii) AlCl_(3) + 3NH_(4)OH rarr Al (OH)_(3)darr +3NH_(4)Cl`
`Al(OH)_(3)+NaOH rarr NaAlO_(2)+2H_(2)O`