Question

How many electrons are in the outermost shell of the K+ ion in its ground state?​

Answer 1

If we look at the electron configuration of potassium (K), we see that it has one electron: [Ar]4s1. Obviously, removing that electron gives us [Ar] (same configuration as K1+), which is a noble gas and has 8 electrons. Valence electrons are generally regarded as being 'the outermost electrons' for a given atom