Use the law of definite proportions and the equation below to answer the questions. The law of definite proportions states that regardless of the amount, a compound is always composed of the same elements in the same proportion by mass.
Mass percentage of an element (%) = mass of element/mass of compound x 100.
A 20.0-g sample of sucrose contains 8.4 g of carbon. What is the mass percentage of carbon in sucrose? Show your work.