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 mole is that amount of substance of a system that contains exactly 6.022 141 79 x 1023 specified elementary entities, which may be atoms, molecules, ions, electrons, other particles, or specified groups of such particles.he mole is that amount of substance that contains the same number of elementary entities as there are atoms in 12 g of carbon 12. When the mole is used, the entities must be specified and may be atoms, molecules, ions, electrons, other particles, or specified groups of such particles.