An aliphatic hydrocarbon A on treatment with sulphuric acid in the presence of `HgSO_4` yields a liquid B with molecular formula `C_2H_4O`. Bon oxidation with acidified potassium dichromate yields C which gives effervescence with sodium bicarbonate. C when treated with `SOCl_2` gives D. When D reacts with ethanol it gives a sweet smelling liquid E. E is also formed when C reacts with ethanol in the presence of conc. `H_2SO_4`.
Identify A, B, C, D and E.

Explanation

`{:(CH -= CH + H_2O underset(HgSO_4)overset(H_2SO_4)to CH_3CHO),([A]" " [B]):}`