A sample of polystyrene prepared by bulk polymerization at 60°C using radioactive 14C-AIBN as initiator was found to have a number average molar mass (Mn) of 1000 kg/mol and a radioactivity of 6 x 103 counts/(s. g). Given that the 14C-AIBN has a radioactivity of 6x109 counts/(s. mol). Determine the mode of termination that operated during preparation of the polystyrene sample. (Note: bulk polymerization means that no solvent is used, and the reaction is carried out in pure liquid monomer).

You are attempting to recrystallize a crude product mixture. you add the appropriate amount of hot solvent and are allowing the solution to slowly cool to room temperature. however, at room temperature no crystals have appeared, which of the following methods should be used to induce crystallization? choose all correct answers. a) place the flask in an ice bath. b) swirl the contents of the flask. c) add a small seed crystal of the desired product. d) scratch the inside of the glassware using a stir rod. it can be multiple choices