We are given with a compound, Phosphorus (P) having a 1.2x 10 ^25 atoms. We are tasked to solve for it's corresponding moles.
Not that 1 mol=6.022x10^{23} atoms, hence,
mol P = 1.2x 10 ^25 atomsx 1 mol/6.022x10^{23} atoms = 19.93 mols
Therefore, the moles of Phosphorus is 19.93 mols.