Write the molecular formula of benzene and state the number of double bonds in its structure.

Which functional group is present in alcohol?

What is the difference between two consecutive members in a homologous series of alkanes in terms of:
$(i)$ molecular mass.
$(ii)$ number of atoms of elements.

Identify and name the functional groups present in the following compounds.
$(a)$ $CH_3-CO-CH_2-CH_3$
$(b)$ $CH_3-CH_2-CH=CH_2$

What happens when: $(i)$ ethanol is burnt in air and $(ii)$ it is oxidized? Write the corresponding reaction equations.

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