Write $IUPAC$ names of the following compounds:
$(i)$ $(CH_3)_2CH-CH=CH-CH_2-CH=C(CH_3)-CH(C_2H_5)-CH_3$
$(ii)$ The structure is shown below:
$(iii)$ $CH_2=C(CH_2CH_2CH_3)_2$
$(iv)$ $CH_3-CH(CH_3)-CH=C(C_2H_5)-CH_2-CH(CH_3)-CH_2CH_2CH_3$

(N/A) $(i)$ The longest chain containing both double bonds has $10$ carbons. Numbering from the left gives $2,8-$dimethyl$-3,6-$decadiene.
$(ii)$ The structure is $CH_2=CH-CH=CH-CH=CH-CH=CH_2$,which is $1,3,5,7-$octatetraene.
$(iii)$ The longest chain containing the double bond has $5$ carbons with a propyl group at position $2$. The name is $2-$propylpent$-1-$ene.
$(iv)$ The longest chain containing the double bond has $10$ carbons. Numbering from the left gives $4-$ethyl$-2,6-$dimethyl$-4-$decene.