1. Calculate the average atomic mass of iron if its abundance in nature is 15%-iron-55 and 85% iron-56

The average atomic mass of iron : 55.85 amu

The elements in nature have several types of isotopes

Isotopes are atoms whose no-atom has the same number of protons while still having a different number of neutrons.

An atomic mass unit = amu is a relative atomic mass of 1/12 the mass of an atom of carbon-12.

The 'amu' unit has now been replaced with a unit of 'u' only

Atomic mass is the average atomic mass of all its isotopes

atomic mass X = mass isotope 1 . % + mass isotope 2.% ...

The average atomic mass of iron

i would say b

explanation:

but i think i would need more information than that

i think it's c. if you look search electronic symbol on google and then click on wiki it shows you a