How many calcium atoms would be in a 100 g sample of calcium

 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

it is the most commonly accepted one