An alcohol $\left(\mathrm{A}\right)$ on treatment with $\mathrm{conc}.{\mathrm{H}}_2{\mathrm{SO}}_4$ gave an alkene $\left(\mathrm{B}\right)$. The compound $\left(\mathrm{B}\right)$, on reacting with ${\mathrm{Br}}_2$ water and subsequent dehydrobromination with ${\mathrm{NaNH}}_2$produced a compound $\left(\mathrm{C}\right)$. The compound $\left(\mathrm{C}\right)$ with  $\mathrm{dil}.{\mathrm{H}}_2{\mathrm{SO}}_4$ in presence of ${\mathrm{HgSO}}_4$ gave a compound $\text{'}\mathrm{D}\text{'}$. The compound $\mathrm{D}$ can also be obtained by oxidation of $\mathrm{A}$ by acidified ${\mathrm{KMnO}}_4$ or from dry heating of calcium acetate. Calculate molecular weight of $\text{'}\mathrm{C}\text{'}$.