BaCl2 + H2SO4
giai phuong trinh hoa hoc

500bc indiais the answer.

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.

Any vitamins or supplements can be obtained without prescription and are widely used as alternative from western medications. most supplements are not valued by the fda or any other drug and food agencies.