What value do you estimate for zeff experienced by the outermost electron in both na and k by assuming core electrons contribute 1.00 and valence electrons contribute 0.00 to the screening constant?

We know that both Sodium atom (Na) and Potassium atom (K) are alkali metal. They are called as alkali metal due to the ability to form an alkali or a base namely NaOH and KOH of these metals. If we assume that all inner electrons shield to the same degree, then any alkali metal will have a Zeff of +1. 

that's what i got you can count the number of atoms