Answer:
Avogadro's number is a constant.
Step-by-step explanation:
In sciences like physics or chemistry exist constants, like Avogadro's number or the Gravitational constant. This means that those magnitudes are always the same no matter the environment, like light's velocity for example. This magnitudes can be used as constants because only could change in extreme environments.
So, as a constant, Avogadro's number is present in every mole, because indicate the number of molecules in one mole, no matter which element it is.