Mass percentage composition of carbon in the compound is the composition of carbon in the compound. This can be calculated by finding out the mass of carbon in the compound and the mass of the whole compound .
The compound formula is C2H5Cl
Mass of 1 mol of compound -64.5 g
Mass of carbon - 24 g
Mass percentage = 24/64.5 x100
Therefore mass composition percentage of carbon = 37.2%