An aqueous solution of a gas (X) gives the following reactions :
(i) It decolourizes an acified `K_(2)Cr_(2)O_(7)`.
(ii) On boiling with `H_(2)O_(2)`, cooling it and then adding an aqueous solution of `BaCI_(2)`, a precipitate insoluble in dilute HCI is obtained.
(iii) On passing `H_(2)S` gas in the solution, white turbidity is obtained. identify (X) and give equations for steps (i), (ii) and (iii).

Answer

`X=SO_(2)`

Explanation

(i) `Cr_(2)O_(7)^(2-)+3SO_(2)+2H^(+)to2Cr^(3+)+3SO_(4)^(2-)+H_(2)O`
(ii) `H_(2)O_(2)toH_(2)O+O`
`SO_(2)+H_(2)O+[O]toH_(2)SO_(4)`
`H_(2)SO_(4)+Ba^(2+)toBaSO_(4)darr("white")+2H^(+)`
(iii) `H_(2)S+SO_(2)overset(H_(2)O)to2H_(2)O+2Sdarr("white turbidity")`