Why does coppers configuration have a full outer sub shell?

One or more substances changing into one or more substances is an example of a

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?

If you have 5.25 grams of methane (ch4), how many grams of co2 will you produce ?