Explain the following reactions with one example for each giving relevant chemical equations : (i) Hydrogenation reaction,
(ii) Oxidation reaction,
(iii) Substitution reaction,
(iv) Saponification reaction.

Explanation

When carbonic acid reacts with alcohol n the presenee of cone. `H_(2)SO_(4),` pleasant fruity smelling compound is formed this type of reaction is called esterification reaction.
`underset("Ethanoic acid")(CH_(3)COOH_(1))+ underset("Ethanol")(C_(2)H_(5)OH_(1))underset(H_(2)SO_(4))overset("Alkaline")rarr underset("Ethyl ethanoate")(CH_(3)COOC_(2)H_(5(1)))+ underset("Water")(H_(2)O_(1)`)
(i) Oxidation reaction :
`underset("Ethanol")(CH_(3)CH_(2)OH)+2[O] underset("KMnO"_(4))overset("Alkaline")rarr underset("Ethonoic")(CH_(3)COOH+H_(2))O`
(ii) Addition rection:
`underset ("Ethene")(CH_(2))=CH_(2)+H_(2)underset("573K")overset("Ni")rarr CH_(3)- CH_(3)`
(iii) Substitution reaction :
`underset("Methane")(CH_4)+Cl_(2) overset("Sunlight")rarr underset("Methylchoride")(CH_(3)Cl+HCl)`