There are 43.2 g of carbon to 14.4 g of hydrogen in a sample of methane (CH4). What percent of 37.8 g of methane is carbon?

Using the law of constant proportions which says that within the same compound, elements exist in fixed ratios.

Therefore; we can use the ratio of total mass to the mass of carbon, to determine the amount of carbon in another sample.

Mass C / Mass CH4 = Mass C / Mass CH4

43.2 g / 57.6 g = Mass C / 37.8 g

Mass C = 37.8 g * 43.2 g / 57.6 g

= 28.35 g

Hence; the percentage of carbon will be;

= (28.35 / 37.8) * 100%

= 75 %

Thus; 75% of 37.8 g of methane is carbon