Explain the method of preparation of aldehydes and ketones from hydrocarbon (alkene and alkyne) compounds with suitable examples.

(N/A) $i$. By ozonolysis of alkenes: Ozonolysis of alkenes followed by reaction with zinc dust and water gives aldehydes,ketones,or a mixture of both,depending on the substitution pattern of the alkene.
$1$. Preparation of methanal from ethene:
$CH_2=CH_2 + O_3$ $\rightarrow \text{Ethylene ozonide}$ $\xrightarrow{Zn, H_2O} 2HCHO + ZnO$
$2$. Preparation of ethanal and methanal from propene:
$CH_3-CH=CH_2 + O_3$ $\rightarrow \text{Propene ozonide}$ $\xrightarrow{Zn, H_2O} CH_3CHO + HCHO + ZnO$
$3$. Preparation of propanone and methanal from $2$-methylpropene:
$(CH_3)_2C=CH_2 + O_3$ $\rightarrow \text{Ozonide}$ $\xrightarrow{Zn, H_2O} CH_3COCH_3 + HCHO + ZnO$
$ii$. By hydration of alkynes: Alkynes react with water in the presence of $H_2SO_4$ and $HgSO_4$ to form carbonyl compounds.
$e.g.$,Ethyne on hydration gives ethanal:
$HC \equiv CH + H_2O$ $\xrightarrow{H_2SO_4, HgSO_4} [CH_2=CHOH]$ $\rightarrow CH_3CHO$