Which among the following polymers belongs to the class elastomers?

$A$ polymer contains $50$ molecules with molecular mass $5,000$,$100$ molecules with molecular mass $10,000$ and $50$ molecules with molecular mass $15,000$. Calculate the number average molecular mass. (in $,000$)

Which of the following is a co-polymer?

Identify the homopolymer from the following.

Which of the following statements is not true?

Which of the following polymers soften on heating and harden on cooling? What are the polymers with this property collectively called? What are the structural similarities between such polymers?