Why does cis-polyisoprene exhibit elasticity ?

Explanation

Natural rubber or cis-polyisoprene does not have a polar group. Hence, their chains are lined by weak van der Waals forces. The cis-configuration of the double bond doesn's allow the chains to get close to one another. This leads to the chain structure. Thus, natural rubber can be stretched like a spring which recoils back when stretching force is removed, i.e., cis-polyisoprene shows elasticity .