Which method is most likely used to identify what happened before the start of the paleozoic era?

How would the number of moles (n) of o2 change if the atmospheric pressure doubled but all other variables stayed the same

How are isotopes of the same chemical element alike? how are they different?

The atom fluorine generally will become stable through the formation of an ionic chemical compound by accepting electron(s) from another atom. this process will fill its outer energy level of electrons.