How many chlorine atoms are there in two calcium chloride formula units?

Calcium chloride has the following formula: CaCl2

Based on this formula: one mole of calcium chloride contains two moles of chlorine

Therefore: two moles of calcium chloride would contain four moles of chlorine.

Number of atoms = number of moles x Avogadro's number

Number of atoms = 4 x 6.022 x 10^23 = 2.4088 x 10^24 atoms