Draw the formulae for the first five numbers of each homologous series beginnig with the following compounds:
a. `H - COOH`
b. `CH_(3) COCH_(3)`
c. `H - CH = CH_(2)`

Explanation

(a)
H–COOH : Methanoic acid
`CH_(3)–COOH` : Ethanoic acid
`CH_(3)–CH_(2)–COOH` : Propanoic acid `CH_(3)–`
`CH_(2)–CH_(2)–COOH` : Butanoic acid `CH_(3)–CH_(2)–`
`CH_(2)–CH_(2)–COOH` : Pentanoic acid
(b) `CH_(3)COCH_(3)` : Propanone
`CH_(3)COCH_(2)CH_(3)` : Butanone
`CH_(3)COCH_(2)CH_(2)CH_(3)` : Pentan-2-one
`CH_(3)COCH_(2)CH_(2)CH_(2)CH_(3)` : Hexan-2-one
`CH_(3)COCH_(2)CH_(2)CH_(2)CH_(2)CH_(3)` : Heptan-2-one
(c )
`H–CH=CH_(2)` : Ethene `CH_(3)–`
`CH=CH_(2)` : Propene `CH_(3)–CH_(2)–`
`CH=CH_(2)` : 1-Butene
`CH_(3)–CH_(2)–CH_(2)–CH=CH_(2)` : 1-Pentene
`CH_(3)–CH_(2)–CH_(2)–CH_(2)–CH=CH_(2)` : 1-Hexene