Define structural isomers as compounds with the same molecular formula, but different structural formulae, including (C_4H_{10}) as (CH_3CH_2CH_2CH_3) and (CH_3CH(CH_3)_2CH_3) and (C_4H_8) as (CH_3CH_2CH=CH_2) and (CH_3CH=CHCH_3)

Describe the properties of alkenes in terms of addition reactions with: (a) bromine or aqueous bromine (b) hydrogen in the presence of a nickel catalyst (c) steam in the presence of an acid catalyst and draw the structural or displayed formulae of the products