When sodium carbonate (na2co3) dissolves in water, it partially ionizes. the carbonate (co3-) ion takes up a hydrogen ion and forms hco3-. what type of substance is sodium carbonate? ! strong base weak acid strong base weak base

Sodium Carbonate is a strong base! Hope this helps!

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.