Question

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

Answer 1

The average atomic mass of iron : 55.85 amu

Further explanation

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

$\tt =0.15\times 55+0.85\times 56\\\\=\boxed{\bold{55.85~amu}}$