Question

A gaseous mixture composed of 20% CH4, 30% C2H4, 35% C2H2, and 15% C2H2O. What is the average molecular weight of the mixture?

(a) 20

(b) 25

(c) 6.75

(d) 9.25

Answer 1

Right option is (c) 6.75

To elaborate: Since it is a gaseous mixture so the percentages are by mole, => average molecular weight of mixture = {(20/100)*16 + (30/100)*28 + (35/100)*26 + (15/100)*42}/4 = 6.75.