Help me solve this please!?

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?

What is a possible quantum number set for an electron in the 3s orbital of a magnesium atom

(04.05 hc) analyze the given diagram of the carbon cycle below. part 1: which compound does c represent? part 2: name a process that could release this compound into the air. part 3: explain how the elements that form it are conserved during the carbon cycle. use complete sentences to explain your answer. justify how this compound was created from a recycling of carbon in the carbon cycle. use complete sentences to explain your answer.