Question

A regular co-polymer of ethylene and vinyl chloride contains alternative monomers of each type. The mass percent of ethylene in this co-polymer is (as the nearest integer) :

Answer 1

The molar masses of ethylene ad vinyl chloride are 28 g/mol and 62.5 g/mol respectively.
Since the ratio of ethylene and vinyl chloride in the polymer is 1:1, the mass percent of ethylene in the co polymer is
$\frac{\text{Molar mass of ethylene}}{\text{Molar mass of ethylene + molar mass of vinyl chloride}}\times 100=\frac{28}{28+62.5}\times 100=31$ %