Question

Help please: https://snipboard.io/69vOth.jpg

Answer 1

Ok so what is the problem you need?

Answer 2

Zeff = Z - S

Z is the atomic number. Because both these atoms are neutral, # of protons = # of electrons

S = shielding electrons, or the # of electrons in the completed shells

So for both, Zeff = total electrons - completed shells, or simply the # of electrons in the outermost shell

Calculate Zeff for both and the solution should be clear