Carbon is not combustible because when it combines with oxygen its energy increases thus it doesnt combust.
Answer is 4 ½ billion.
Scientists think the earth's age is 4 ½ billion. This calculation is based on the radioactive dating. Since the formation of the earth, the time period has been divided into 3 major geological time periods as eon. They are phanerozoic, proterozoic and archean.
It is -2 because the charge will be at zero and electrons lower the charge
