Final answer:
The mass of 1 mole of magnesium is 24.305 grams; when expressed to four significant figures, it is 24.30 g.
Step-by-step explanation:
The mass of 1 mole of magnesium can be determined by its molar mass, which is the mass of one mole of a substance. Magnesium has a molar mass of 24.305 g/mol. Therefore, the mass of 1 mole of magnesium would be 24.305 grams.
In expressing this number to four significant figures, we get 24.30 g, which appropriately reflects the precision of the value based on molar mass.