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).
A mole is defined as the number of atoms in exactly 12 grams of C (carbon twelve). The number is called Avogadro's Number. In the above definition, 12 is the mass number of carbon.So, one mole of carbon atoms has a mass of 12 grams. The relative atomic mass, which can be written as Ar or RAM, is the number just above the element in the periodic table (have a look, and check that carbon is 12). mole is defined as the number of atoms in exactly 12 grams of C (carbon twelve). The number is called Avogadro's Number. In the above definition, 12 is the mass number of carbon.