(i) Mechanism of hydration of ethene to ethanol
Step-I: Protonation of alkene
Step-II: Nucleophilic attack of water as carbocation
Step-III: Deprotonation of alcohol
(ii) Mechanism of dehydration of ethanol to ethene.
Step-I: Formation of protonated alcohol
Step–II: Formation of carbocation
Setp-III. Formation of ethene