${H_3}C - C \equiv CH\,\xrightarrow[{HgS{O_4}}]{{{H_2}O,\,{H_2}S{O_4}}}\,\mathop {intermediate}\limits_{(A)} \,$$ \to \,\mathop {\Pr oduct}\limits_{(B)} $
${C_6}{H_5}C{H_3}\xrightarrow{{Oxidation}}A\xrightarrow{{NaOH}}B\xrightarrow[\Delta ]{{sodalime}}C$