The grams of oxygen that would produce 13.4 g Cl^2O^7 molecules.

Answer 1

The fraction of a Cl2O7 molecule's mass that is oxygen is
(16*7)/[16*7 + 2*35.5)
= 112/183 = 0.612

Multiply that by 13.4 g for the answer.

Answer 2

Thank you.