C. The law that was used to determine the relationship between the volume and the number of moles is Avogadro’s law.
Avogadro's law states that equal volumes of any gas contain the same number of molecules at the same temperature and pressure.
V ∝ n
where;
Thus, the law that was used to determine the relationship between the volume and the number of moles is Avogadro’s law.
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