in 1 mole there are=6.0210^23 particles
so there are 2 cl atoms
1.8110^24 MgCl2 should containt 2(1.8110^24) atoms...21.810^24 = 3.6 10^24
as we knw 1 mole contains 6.0210^23 particle
so x mole contains 3.6*10^24 particle
so approximately there are 6 moles of chlorine atoms
hope it helps
