For each of the following pairs of polymers, do the following: (1) State whether it is possible to determine whether one polymer is more likely to crystallize than the other; (2) if It Is possible. note which is the more likely and then cite reason(s) for your choice; and (3) if it is not possible to decide, then state why.

(a) Linear and atactic poly(vinyl chloride); linear and isotactic polypropylene

(b) Linear and syndiotactic polypropylene; crosslinked cis-polyisoprene

(C) Network phenol-formaldehyde; linear and isotactic polystyrene

(d) Block poly(acrylonitrile-isoprene) copolymer; graft poly(chloroprene-isobutylene) copolymer