$\mathrm{CH}_{3}-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_{3} \frac{\mathrm{o}_{3}}{-2 \mathrm{m}_{2} \mathrm{O}} 2 . \mathrm{CH}_{3} \mathrm{CHO}$
Also, molar mass of $CH_3CHO$ is $44\; u.$
${C_2}{H_2}\xrightarrow[{HgS{O_4}/{H_2}S{O_4},60{\,^o}C}]{{{H_2}O}}X \rightleftharpoons C{H_3}CHO$