Calculate the various ratios of 2-methylbutane​

Isec i will do it and them i will let you know

Ithink about 50 % of an original isotope's number of atoms remain

Remember that rust prevented by placing a sacrificial electrode in electrical contact with the iron. the sacrificial electrode must be composed of a metal that  oxidizes  more easily than iron (that is, it must be below iron in table 18.1).