How many milligrams of calcium are there if you have 1.05 x 1022 atoms

The answer is 115.22

698mg

Explanation:

1 mole of any substance contains 6.02x10^23 atoms as explained by Avogadro's hypothesis. This means that 1mole of Ca also contains 6.02x10^23 atoms.

1mole of Ca = 40g

40g of CO2 contains 6.02x10^23 atoms.

Therefore, Xmol of Ca will contain 1.05 x 1022 atoms i. e

Xmol of Ca = (40 x 1.05 x 1022) / 6.02x10^23 = 0.698g

Recall: 1g = 1000mg

0.698g = 0.698 x 1000 = 698mg