(R)-Limonene (1-methyl-4-isopropenylcyclohex-1-ene, C10H16) is treated with excess O3 followed by Zn/H2O. The organic product X (C9H14O3, other than…

Limonene has two C=C bonds: the trisubstituted ring alkene and the 1,1-disubstituted isopropenyl group. With excess ozone both are cleaved, so $2$ mol of $\mathrm{O_3}$ are consumed. Reductive work-up of the ring alkene opens the ring to give a methyl ketone at the former $\mathrm{C1}$ and an aldehyde at the former $\mathrm{C2}$; the isopropenyl group gives a methyl ketone on the ring carbon and releases $\mathrm{HCHO}$. Thus $\mathbf{X}=\mathrm{CH_3CO{-}CH_2CH_2{-}CH(COCH_3){-}CH_2{-}CHO}$, $\mathrm{C_9H_{14}O_3}$. Under $\mathrm{I_2/NaOH}$ each $\mathrm{CH_3C(=O){-}}$ group is converted to $\mathrm{CHI_3}$ plus a carboxylate. There are two such methyl ketone groups, so $2$ mol of $\mathrm{CHI_3}$ form; the aldehyde does not give iodoform. The total is $2+2=4$.