Her behavior has been reinforced (i.e. strengthened). Reinforcement can be external or internal and can be positive or negative. If a child wants approval from parents or peers, this approval is an external reinforcement, but feeling happy about being approved of is an internal reinforcement.
It remained to define the unit of amount of substance by fixing the corresponding mass of carbon 12; by international agreement, this mass has been fixed at 0.012 kg, and the unit of the quantity amount of substance was given the name mole (symbol mol).
mole 3. The amount of an element or substance that has a mass in grams numerically equal to the atomic or molecular weight of the substance. For example, carbon dioxide, CO2, has a molecular weight of 44; therefore, one mole of it weighs 44 grams. The number of atoms or molecules making up a mole is Avogadro's number.