What is a mole? And how do I calculate it?

A mole is defined as the amount of substance it can be expressed as gram ,

atom , molecules etc ...

to go fr gram to mole divided gram by molar mass

because u need two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei to form isotopes.

so since they all have the same shape? i mean maybe because m& m and reeses are both chocolates

it’s previous models   because when i picked that son of a gun’s answer it was wrong look for previous models because they might make it a different letter