$A$ hydrocarbon,$C_{2}H_{4}$,decolorizes bromine water.
$(i)$ Name the hydrocarbon.
$(ii)$ Mention the family to which it belongs.
$(iii)$ Write the chemical equation of the reaction of this hydrocarbon with hydrogen.

(A) $(i)$ The hydrocarbon is Ethene.
$(ii)$ It belongs to the Alkene family.
$(iii)$ The reaction of Ethene with Hydrogen in the presence of a catalyst (like Nickel or Palladium) results in the formation of Ethane:
$C_{2}H_{4} + H_{2} \xrightarrow{Ni/Pd} C_{2}H_{6}$