"A crosslinked copolymer consists of 57 wt% ethylene (C2H4) repeat units and 43 wt% propylene (C3H6) repeat units. Determine the fraction of (a) ethylene and (b) propylene repeat units."

Explanation:

Percentage ethylene by weight = 57%

Percentage propylene by weight = 43%

Suppose in 100 grams of polymer:

Mass of ethylene = 57 g

Mass of propylene = 43 g

Moles of ethylene =

Moles of propylene =

1 mole = molecules/ atoms

Units of ethylene =

Units of propylene =

a) Fraction of ethylene units:

b ) Fraction of propylene units:

answer: i would say b.

explanation:

"the periodic table is arranged in order of atomic number."