transverse waves have a speed of 0,5 m-s¹ and a wavelength of 25 mm calculate the frequency of the waves.​

Letter a hope it

D.na is the answer hope this

The answer is a) carbon-12

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.