Determine the number of moles in 549 grams of kno3

KNO3=40+14+16*3=210 no. of moles=given mass/molarmass. n=m/M= no. of moles=given mass/molar mass =549/210 =2.61

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.