The element x has three naturally occurring isotopes. the masses (amu) and % abundances of the isotopes are given in the table below. the average atomic mass of the element is amu.

220.42098 amu

Explanation:

(220 .9 X  .7422) + (220 X .0.1278) + (218.1 X 0.13) =     220.42098 amu

These are weighted averages.

So, we will take mass of one and multiply by abundance percentage that is provided and add them together.

In order to calculate the  average atomic mass, we have to convert the percentages of abundance to decimals. So, you get

(220 .9 X  .7422) + (220 X .0.1278) + (218.1 X 0.13) =     220.42098 amu

if two electrons have the same n, the same ℓ, and the same ml, then they are in the same orbital. the pauli exclusion principle states that no two identical fermions (a fancy word for electrons and other subatomic particles like electrons) may occupy the same quantum state in an atom simultaneously.