Ok hi what is the question
The atomic mass of an element is the average mass of an element's naturally occurring atom, or isotopes, taking into the account the isotopic mass<em> </em><em />of each isotope.
Answer:
4s, 3d, 4p
Explanation:
(3d,4s,4p) and (4p, 3d, 4s) both are decreasing energy, while (4s,4p,3d) is incorrect order it should be (4s,3d,4p).