Derive the structure of $(i)$ $2-$Chlorohexane,$(ii)$ Pent$-4-$en$-2-$ol,$(iii)$ $3-$Nitrocyclohexene,$(iv)$ Cyclohex$-2-$en$-1-$ol,$(v)$ $6-$Hydroxyheptanal.

(N/A) $(i)$ 'hexane' indicates the presence of $6$ carbon atoms in the chain. The functional group chloro is present at carbon $2$. Hence,the structure is $CH_3-CH_2-CH_2-CH_2-CH(Cl)-CH_3$.
$(ii)$ 'pent' indicates that the parent hydrocarbon contains $5$ carbon atoms. 'en' and 'ol' correspond to the functional groups $C=C$ and $-OH$ at carbon atoms $4$ and $2$ respectively. Thus,the structure is $CH_2=CH-CH_2-CH(OH)-CH_3$.
$(iii)$ $A$ six-membered ring containing a carbon-carbon double bond is implied by cyclohexene. The prefix $3-$nitro means that a nitro group is present on $C-3$. The double bond gets preference over the $-NO_2$ group. The structure is a cyclohexene ring with a double bond between $C-1$ and $C-2$ and a $-NO_2$ group at $C-3$.
$(iv)$ '$1-$ol' means that a $-OH$ group is present at $C-1$. The $-OH$ group is the principal functional group and gets preference over the $C=C$ bond. Thus,the structure is a cyclohexene ring with $-OH$ at $C-1$ and the double bond between $C-2$ and $C-3$.
$(v)$ 'heptanal' indicates an aldehyde containing $7$ carbon atoms. The '$6-$hydroxy' indicates that an $-OH$ group is present at carbon $6$. Thus,the structural formula is $CH_3-CH(OH)-CH_2-CH_2-CH_2-CH_2-CHO$.