Answer 2: 1 mole = 6.03 x 1023 particles. One mole of any element has a mass in grams that is equal to its atomic number, and has exactly 6.02 x 1023 atoms - however because the atoms of each element have different sizes and weights, then the volume that each one occupies is different.
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https://scienceline.ucsb.edu/getkey.php?key=274
