Answer:
"Avogadro's law is an experimental gas law relating the volume of a gas to the amount of substance of gas present. The law is a specific case of the ideal gas law. A modern statement is: Avogadro's law states that "equal volumes of all gases, at the same temperature and pressure, have the same number of molecules."
They can use them to find the age of fossils.
9.00g/1hr * 1kg/100g * 1hr/60min = 0.00015kg/min or 1.5 * 10^-4kg/min.