A white substance (A) reacts with dilute H_(2)SO_(4) to produce a colourless gas (B) and a colourless solution (C). The reaction between (B) and acidified K_(2)Cr_(2)O_(7) solution produces a green solution and a slightly coloured precipitate (D). Addition of aqueous ammonia or sodium hydroxide to (C) produces first a precipitate, which dissolves in the excess of teh respective reagent to produce a clear solution in each case. The colourless gas (B) is:

A white substance (A) reacts with dilute H_(2)SO_(4) to produce a colo

1.	A white substance (A) reacts with dilute H_(2)SO_(4) to produce a colourless gas (B) and a colourless solution (C). The reaction between (B) and acidified K_(2)Cr_(2)O_(7) solution produces a green solution and a slightly coloured precipitate (D). Addition of aqueous ammonia or sodium hydroxide to (C) produces first a precipitate, which dissolves in the excess of teh respective reagent to produce a clear solution in each case. The colourless gas (B) is:
Answer» `H_(2)S` `SO_(2)` `CO_(2)` `NO` Solution :`(A) RARR ZnS, (B) rarr H_(2)S, (C) rarr znSO_(4)` `H_(2)S +K_(2)Cr_(2)O_(7) rarr underset((D))(Sdarr)+ underset(("Green"))(Cr^(3+))` `ZnSO_(4)+ NH_(4)OH rarr [Zn(NH_(3))_(4)]^(2+)` `Zn^(2+) +K_(4)[Fe(CN)_(6)] rarr underset(("White/bluish ppt"))(K_(2)Zn_(3)[Fe(CN)_(6)]_(2)DARR)`