100 grams of magnesium:
1 mole of Mg atom = 6.022 × 1023 atoms
This means 24g of Mg has 6.022 × 1023 atoms
Then 100 g contains:
Number of Mg atoms = \(\frac{Given\,mass}{Molar\,mass}\)x 6.022 x 1023
Number of Mg atoms = \(\frac{100g}{24u}\)x 6.022 x 1023
Number of Mg atoms = 2.5 × 1024 atoms
100 grams of aluminium:
1 mole of Al atom = 6.022 × 1023 atoms
This means 27g of Al has 6.022 × 1023 atoms
Then 100 g contains:
Number of AI atoms = \(\frac{Given\,mass}{Molar\,mass}\)x 6.022 x 1023
Number of AI atoms = \(\frac{100g}{27u}\)x 6.022 x 1023
Number of AI atoms = 2.2 x 1024
Thus, 100g of magnesium has more atoms.