Give the different structures and names of the following alkyl groups:
$(a)$ Propyl group
$(b)$ Butyl group
$(c)$ Pentyl group

(N/A) Propyl group:
$1$. $n$-Propyl group: $CH_3-CH_2-CH_2-$
$2$. Isopropyl group: $(CH_3)_2CH-$
$(b)$ Butyl group:
$1$. $n$-Butyl group: $CH_3-CH_2-CH_2-CH_2-$
$2$. Isobutyl group: $(CH_3)_2CH-CH_2-$
$3$. sec-Butyl group: $CH_3-CH_2-CH(CH_3)-$
$4$. tert-Butyl group: $(CH_3)_3C-$
$(c)$ Pentyl group:
$1$. $n$-Pentyl group: $CH_3-CH_2-CH_2-CH_2-CH_2-$
$2$. Isopentyl group: $(CH_3)_2CH-CH_2-CH_2-$
$3$. Neopentyl group: $(CH_3)_3C-CH_2-$