If you have exactly 2.00 moles each, of two different substances, then which of the following must be true about the two samples? they have the same mass. they have the same weight. they have the same number of particles. both b and c.

1 mole of any substance contains 6.022 x 10²³ molecules. however the masses of moles may vary between elements. The molar masses of different elements vary. e.g.; Na molar mass is 23 g/mol whereas Mg molar mass is 24 g/mol.
1 mol of Na weights 23 g whereas 1 mol of Mg weighs 24g.
If 2 substances have same number of moles, their masses may vary depending on the molar masses of the elements but the number of particles of both substances are the same.
correct answer is they have the same number of particles