Give two uses of compound under each of the following, in medicine and in industry​

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?

According to coulomb's law, how would the electrical force between particles change if the product of their electrical charge increased?

Which metal exist in liquid state and can be cut with knife ?