Answer: There is no isotactic or syndiotactic form of polyethylene.
Explanation: Polyethylene is a type of polymer that is made up of repeating units of ethylene monomers. The polymer chains in polyethylene are arranged randomly, without any specific stereochemistry, which means that there is no isotactic or syndiotactic arrangement of the polymer chains. The lack of stereochemistry in polyethylene results in a material that is amorphous and has low crystallinity, which gives it unique mechanical and physical properties that make it useful for a wide range of applications.