Question: how to calculate mass percentage of methane?
Answer: In methane there are only 2 elements, Carbon and Hydrogen. The total mass of a methane molecule (CH4) is. 4 x 1 + 12 = 16. %mass of H in methane= 4/16 x 100% = 25% %mass of C in methane = 12/16 x 100% = 75%