An aqueous solution of a gas 'A ' gives the following reactions along with same observations:
When the solution is boiled with `H_(2)O_(2)` , cooled and an aqueous solution of `BaCl_(2)` is added to the mixture, a white precipitate insoluble in dilute HCl is obtained.

Explanation

These observations suggest that the gas A is sulphur dioxide `(SO_(2))` . The reaction involved are as follows.
`H_(2)O_(2) + SO_(2)(A) overset(Delta) to H_(2)SO_(4)`
`H_(2)SO_(4) + BaCl_(2) to BaSO_(4) darr"(white)"+ 2HCl`