How many atoms of ca are present in 80.156 grams of ca?

1.2044 x 10²⁴ atoms.

Explanation:

n = mass/atomic mass = (80.156 g)/(40.078 g/mol) = 2.0 mol.

Using cross multiplication:

1.0 mole of Ca contains → 6.022 x 10²³ atoms.

2.0 moles of Ca contains → ??? atoms.

∴ 2.0 mole of (80.156 g) Ca contain = (2.0 mol)(6.022 x 10²³) = 1.2044 x 10²⁴ atoms.