Monomer:

\[\begin{array}{cc}
\ce{CH3\phantom{….}}\\
|\phantom{……}\\
\phantom{.}\ce{CH2 = \underset{Isoprene}{C – CH} = CH2}
\end{array}\]

Monomer:

\[\begin{array}{cc}
\ce{Cl\phantom{…….}}\\
|\phantom{……..}\\
\ce{CH2 =\underset{Chloroprene}{C – CH} = CH2}
\end{array}\]

Structure of natural rubber:

\[\begin{bmatrix}\begin{array}{cc}
\ce{H\phantom{…………}}\ce{H}\\
|\phantom{………….}|\\\ce{- C – C = C – C -}\\
|\phantom{….}|\phantom{….}|\phantom{….}|\\
\phantom{}\ce{H\phantom{..}} \ce{CH3\phantom{..}} \ce{H\phantom{…}} \ce{H}
\end{array}\end{bmatrix}_\text{n}\]

Structure of neoprene:

\[\begin{array}{cc}
\ce{Cl\phantom{…….}}\\
|\phantom{……..}\\
\ce{-[CH2 – C = CH – CH2]_{n}}-
\end{array}\]