Question

the empirical formula of hydrocarbon whose carbon percentage is 80%

Answer 1

percentage of C = 80℅
so, hydrogen of H = 20℅


divide percentage by atomic mass of it
e.g for C = 80/12 = 20/3

for Hydrogen = 20/1 = 20

now, C : H = 20/3 : 20 = 1 : 3
so,

empirical formula , = CH3