Which from following polymers is NOT obtained by addition polymerisation method?

Which medicinal property is exhibited by methylsalicylate?

The value of $\left(\dfrac{-1+i\sqrt{3}}{2}\right)^{18} + \left(\dfrac{-1-i\sqrt{3}}{2}\right)^{18}$ is

11 players of the Indian cricket team are sitting at a circular table. The number of ways they can sit so that two players, the wicket keeper and the captain never sit together is ___