Q 2617156080.     A white substance A reacts with dilute `H_2SO_4` to produce a colourless gas B and a colourless solution C. The reaction between B and acidified `K_2r_2 O_7` solution produces a green solution and a slightly coloured precipitate D. The substance D burns in air to produce a gas E which reacts with B to yield D and a colourless liquid. Anhydrous copper sulphate is
turned blue on addition of this colourless liquid. Addition of aqueous `NH_3` or `NaOH` to C produces first a precipitate,
which dissolves in the excess of the respective reagent to produce a clear solution in each case. Identify A, B, C, D and E. Write the equations of the reactions involved.