Question

when acetylene is passed through dil. H2SO4 in presence of HgSO4 the product is

Answer 1

The overall reaction taking place here is "Oxymercuration-Demercuration"
The final product formed is acetaldehyde.

The explanation is in the attachment below..

Hope it helps

Answer 2

hello friend...
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In presence of Acid HgSO4 added a water molecule to the reactant compound. Here reactant compound is Acetylene. So, water will be added to acetylene. This addition is known as Markownikoff's addition.

C2H2 + H2O    -------(Hg+ and H+)----->  H​3C=CH(OH).

again some water molecule will be added, therefore now C has two -OH which makes its unstable form [ CH3-CH(OH)2 ], which further results in the formation of ethanal ( CH3CHO ).
____________________________________ hope it will help you...
best of luck...