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).
THE CONCEPT OF MOLE. A mole is an amount of a substance, also it is a specific number of molecules, formula units, ions, etc. of a substance. A practical definition for a mole is that one mole of a substance is the molecular mass (weight) or formula weight of the substance expressed in grams.