What crossed-aldol product results when butanal is heated in the presence of excess benzaldehyde and sodium hydroxide? draw the molecule on the canvas by choosing buttons from the tools (for bonds), atoms, and advanced template toolbars. the single bond is active by defa?

             2-(hydroxy(phenyl)methyl)butanal is formed as cross aldol product.

Explanation:
                   The mild acidic proton present at alpha position in 1-Butanal is abstracted by strong base NaOH. The enolate formed is the conjugate base of 1-Butanal and cacts as a nucleophile. The enolate is then added across carbonyl group of Benzaldeyde and yield 2-(hydroxy(phenyl)methyl)butanal. The reaction is as follow,

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.