Give $IUPAC$ name of the following:
$(i)$ $CH_3CH_2CH=CHCOOH$
$(ii)$ $CH_2=C(CH_3)-CH(CH(CH_3)_2)-C(CH_3)_3$

(N/A) $(i)$ The parent chain has $5$ carbon atoms with a double bond at position $2$ and a carboxylic acid group at position $1$. Thus,the name is $pent-2-enoic$ acid.
$(ii)$ The longest chain containing the double bond has $6$ carbon atoms. Numbering from the left,we have a methyl group at $C-2$,an isopropyl group at $C-3$,and two methyl groups at $C-4$. Thus,the name is $3-isopropyl-2,4,4-trimethylpent-1-ene$.