Write out the electron configurations for (a) potassium and (b) cobalt. how many unpaired electrons does each possess?

Cobalt has seven electrons in the d sublevel (count how many spaces over it is.) There are 5 orbitals in the d sublevel so the first 5 electrons each take a different orbital (Aufbau Principle.) Each orbital now has one unpaired electron. The last two pair with two of the 5 leaving 3 unpaired electrons.