Answer
(a) Alkyl groups are considered as substituents on parent chain in an organic compound. They are formed by removal of a hydrogen atom from alkane chain.
(b) Structures of alkyl groups
Methyl $-CH_{3}$
Ethyl $-CH_{2}CH_{3}$
Propyl $-CH_{2}CH_{2}CH_{3}$
Butyl $-CH_{2}CH_{2}CH_{2}CH_{3}$
Pentyl $-CH_{2}CH_{2}CH_{2}CH_{2}CH_{3}$
(c) Alkyl group is derived from the name of the corresponding alkane by replacing the -ane suffix with -yl, e.g., methyl, $CH_{3}$, from methane, $CH_{4}$, and ethyl, $C_{2}H_{5}$, from ethane, $C_{2}H_{6}$.
Work Step by Step
Answer is in detail in the attached file.