This will depend on the substance you are talking about. One mole is by definition equal to 6.02 x 1023 molecules or atoms of the substance, but the weight of one molecule or atom will vary depending...
It depends on the element. One mole is 6.02 × 1023 atoms, which has a certain mass. But (for example) one hydrogen atom is going to weigh less than a lithium atom. Therefore, two samples of the two...