What is force and it's so unit?

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?

In the following redox reaction which is the oxidizing agent and which is the reducing agent? alcl3 + na nacl + al

The chart shows the bid provided by four contractors to complete a job. which contractor is the most cost-effective?