Which group of elements on the periodic table forms covalent compounds with other nonmetals

Why does a cake rise when you bake it? ♡

Plz choose one of the compounds from the table and explain how you know the numbers of atoms in your formula. is it possible for two different compounds to be made from the exact same two elements? why or why not? with a limited number of elements (less than 120 are known), does this mean we also have a small number of compounds or do we have a large number of compounds in this world?

Which best describes why nh4+ can form an ionic bond with ci-?