A white solid 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 dichromate yields a green solution and a slightly coloured precipitate D. the substance D, when burnt in air, gives a gas E which reactswith B to yield D and a colourlesss liquid. anhydrous copper sulphate turns blue with this colourless liquid. the addition of aqueous NH_(3) or NaOH toC produces a precipitate that dissolves in an excess of the reagent to form a clear solution. Q. Which of the following gases are B and E respectively?

A white solid A reacts with dilute H_(2)SO_(4) to produce a colourless

1.	A white solid 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 dichromate yields a green solution and a slightly coloured precipitate D. the substance D, when burnt in air, gives a gas E which reactswith B to yield D and a colourlesss liquid. anhydrous copper sulphate turns blue with this colourless liquid. the addition of aqueous NH_(3) or NaOH toC produces a precipitate that dissolves in an excess of the reagent to form a clear solution. Q. Which of the following gases are B and E respectively?
Answer» `CO_(2) and SO_(2)` `SO_(2) and H_(2)S` `H_(2)S and SO_(2)` `CO_(2) and H_(2)S` Solution :One of the three COLOURLESS gases `-CO_(2),SO_(2) and H_(2)S`- is generally PRODUCED by the action of dilute `H_(2)SO_(4)` on a SALT. As the gas turns acidified dichromate solution GREEN along with the formation of slightly coloured precipitate (may be S), the gas seems to be `H_(2)S` and so the substance A seems to be a sulphide. again, the action of `NH_(3)` or an NaOH solution on the solution of the substance in dilute `H_(2)SO_(4)` suggets that the substance is a zinc salt. thus, A is most likely ZnS. let us go through the REACTIONS now.