Menthol (M 156.3 g/mol), the strong-smelling substance in many cough drops, is a compound of carbon, hydrogen, and oxygen. When 0.1595 g of menthol was bunted in a combustion apparatus. 0.449 g of CO_2 and 0.184 g of H_2 O formed.
Each isotope has a unique rate of decay, making them suitable for determining the dates of ancient artifacts. The answer is "rate of decay of the isotope."
