Help out here plz

Iknow the answer is a but i don't know why

How many moles of potassium hydroxide are needed to completely react with 2.94 moles of aluminum sulfate

With the largest atoms and the smallest number of valence electrons and with the smallest atoms and the greatest number of valence electrons are the most reactive. a. nonmetals; metals b. nonmetals; transition elements c. transition elements; metals d. metals; nonmetals