How many particles of calcium are present in 222g of CaCl2 ?
Molar mass of CaCl2= 111g.
Number of moles = mass/molar mass = 222/111 =2.
From formula it is clear that there are 1 Ca radical per molecules of CaCl2.
Number of Ca radicals in 2 mole of CaCl2 = 2 mole. = 2 x 6.023x1023 = 12.023x1023