Question

Each glucose molecule consists only of carbon, hydrogen, and oxygen atoms. If each molecule contains 53.3% oxygen and 6.7% hydrogen by mass, what percentage of each glucose molecule is made up of carbon?

Answer 1

53.3% + 6.7% = 60%, 100% - 60% = 40%. 40% of glucose is made of carbon. Since there are only three types of atoms in glucose, and the amount of hydrogen and oxygen is already given, this means that whatever percentage is left (40%) has to be carbon.