Name the functional group present in the following compounds:
$(i)$ $CH_{3}-CH_{2}-CH_{2}-COOH$
$(ii)$ $CH_{3}-CO-CH_{2}-CH_{3}$

Complete the following chemical reactions and write the chemical name of the products obtained.
$(i)$ $CH_{2}=CH_{2} + H_{2}O \longrightarrow$
$(ii)$ $CH_{3}COOH + NaOH \longrightarrow$
$(iii)$ $CH_{3}CH_{2}OH \xrightarrow{H_{2}SO_{4}} $
$(iv)$ $HCOOH + Na \longrightarrow$
$(v)$ $C_{2}H_{5}OH \xrightarrow{\text{Alk. } KMnO_{4}} $

What is the molecular formula of formic acid (methanoic acid)?

What is the solution of ethanol containing $5\%$ water called?

Vinegar is a solution of :

Explain the given reactions with examples:
$(a)$ Hydrogenation reaction
$(b)$ Oxidation reaction
$(c)$ Substitution reaction