vivtoons

What do you mean by homework question???it is a chemistry question.If you don't know the answer then simply say that you don't know.But at least don't make excuses.

My questions exactly are:

Q 1: Why 3d¹⁰ 4s¹ configuration of copper is more stable than 3d⁹ 4s² in terms of exchange energy ?

Q 2 : Can a electron of 3d exchange to 4s electron, having same spin?

Q3: How many possible exchange sets with a parallel spins can occur in copper ?

Please help me asap.