Identify the compounds A and B in the following reaction sequence.

Calcium carbide forms acetylene 2 2 2 2 2 CaC 2H O Ca H H ( ) O C -> Acetylene on hydration reaction with 4 2 4 / HgSO H SO gives oxymercuration reaction with acetaldehyde as product. 2 3 | 2 4 4 dil.H SO Tautomerism HC CH HC CH CH CHO HgSO OH -> -> Physical & Chemical Properties of Alkynes