The number of calcium atoms that would be in a 100 g sample of calcium is 1.505 x 10²⁴ atoms
calculation
Step 1 ; find the moles of calcium
moles = mass÷ molar mass
from periodic table the molar mass of Ca =40 g/mol
moles is therefore = 100 g÷ 40 g/mol = 2.5 moles
Step 2: use the Avogadro's law constant to determine the number of atoms of Calcium
That is According Avogadro's law 1 mole = 6.02 × 10²³ atoms
2.5 moles=? atoms
{(2.5 moles × 6.02×10²³ atoms) / 1 mole} = 1.505 × 10²⁴ atoms