A candle is placed on one pan of a balance, and an equal weight is placed on the other
pan. What would happen if you lit up the candle and waited for a while?

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.