abs plastic is a polymer consisting of three monomer units: acrylonitrile (c₃h₃n), butadiene (c₄h₆), and styrene (c₈h₈). a sample of abs plastic contains 14.9% n by mass. it took 1.56 g of br₂ to react completely with a 2.00 g sample of abs plastic. bromine reacts 1:1 (by moles) with the butadiene units in the polymer and nothing else, so bromination is a method for determining the quantity of butadiene in the polymer. what is the percent by mass of styrene in the polymer?