During your reaction, you added 0.3 mL concentrated H2SO4 (18.4 M) as the catalyst. At the end of the reaction, you need to add base to neutralize it. How much volume (in mL) of 10% Na2CO3 to neutralize all the acid present

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.

You would do 1500/4 and the answer is 375

In any atom of any element, you will find protons and neutrons in the nucleus of any atom 

Answer///an early form of the atomic theory; dalton atomic theory;