What makes an acid strong (ph of 2)

Thus, it is less capable than a strong acid at donating protons. These acids have higher pKa than strong acids, which release all of their hydrogen atoms when dissolved in water.

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.

Your question is not clear but if you can explain yourself i would be glad to .  just trying to : ))