A sample of hydrogen gas has an initial temperature of 50° C. When the temperature is lowered to -5° C, the volume of hydrogen becomes 212 cm^3. What was the initial volume of the hydrogen in cm^3 when the pressure is kept constant?

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.