8. Iron is an essential chemical element in human body. There are three (3) stable naturally occurring isotope of magnesium as shown in the table below. Isotope no Number of protons Number of neutrons % Abundance 1 12 12 79 2 12 13 10 3 12 14 11 a. Write the symbol for each isotope of magnesium b. By using data in the table above, calculate the average atomic mass of magnesium 9. Element A have two stable isotopes with atomic mass 125 amu and 122 amu. Given that the average atomic mass of element A is 123.87 amu, calculate the percentage abundance of A-125 and A-122