A colourless solid (A) liberates a brown gas (B) on acidification, a colourless alkaline gas (C ) on treatment with NaOH, and a colourless non- reactive gas (D) oh heating. If heating of the solid continued, it completely disappears. Identify (A) to (D).

Explanation

Alkaline gas (C ) with NaOH indicate that solid should be ammonium salt. Heating the salt, a colourless gas (D) non- reactive is formed. The gas (D) may be nitrogen . The compound may thus by `NH_(4)NO_(2)`. Reactions involved may be given as `:`
`(i) underset((A))(NH_(4)NO_(2))overset(HCl)(rarr)NH_(4)Cl+HNO_(2)`
`2HNO_(2)rarr H_(2)O+2NO+[O]`
`2NO+2[O] rarrunderset((B)"Brown gas")(2NO_(2))`
(ii) `underset((A))(NH_(4)NO_(2))+NaOHrarrNaNO_(2)+h_(2)O+underset((C ))(NH_(3))`
`underset((A))(NH_(4)NO_(2))overset("Heat")(rarr)underset((D))(N_(2))uarr+2H_(2)Ouarr`