The most suitable reagent for the following conversion, is :

An alkene “A” on reaction with O₃ and Zn + H₂O gives propanone and ethanal in equimolar ratio. Addition of HCl to alkene “A” gives “B” as the major product. The structure of product “B” is :

Hydrocarbon (A) reacts with bromine by substitution to form an alkyl bromide which by Wurtz reaction is converted to gaseous hydrocarbon containing less than four carbon atoms. (A) is

Predict the correct intermediate and product in the following reaction :

$${H_3}C - C \equiv CH\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{HgS{O_4}}^{{H_2}O,{H_2}S{O_4}}} \mathop {Intermediate}\limits_{(A)} \to \mathop {\Pr oduct}\limits_{(B)} $$