An inorganic compound (A) shows the following reactions. It is white solid and exits as dimer
(i) gives fumes of (B) with much wet air
(ii) It sublimes on `180^(@)C` turns forms monomer if heated to `400^(@)C`
(iii) Its aqueous solution turns blue litmus to red
(iv) Adition of `NH_(4)OH` and NaOH seperately to a solution of (A) gives white precipitate which is however soluble in excess of NaOH
B may be

Options

A. `Cl_(2)`
B. `F_(2)`
C. HCl
D. HF

Answer

C

Explanation

It fumes with wet air
`Al_(2)Cl_(6)+6H_(2)O rarr 2Al(OH)_(3)+ underset((B))underset("Fumes")(6HCl uarr)`