Need answer asap ! which of these elements has four valence electrons? (a). hafnium (hf) (b.) radon (rn) (c.) silicon (si) (d.) sulfur (s)

silicon (Si) had four valence electrons :)

The answer is Silicon. If you ever need a quick way to find out how many valence electrons an element has, look for the element's family. Of course, disregard the transition metals. They are playing their own game.