Any 3 points about importance of measurement in our daily life​

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?

The mass of a neutron is equal to the mass of a proton plus the mass of an electron. true or false false true

What is the correct equation for cellular respiration?