Discuss the significance of assigning an atomic mass of exactly 12 amu to the carbon-12 isotope.

Cabon-12 has same average atomic weight and mass number.

Explanation:

carbon-12 has average atomic weight 12 amu and mass number of 12.

amu represents average of mass of a nucleon.

As carbon-12 has same average atomic mass and mass number therefore carbon-12 is a good standard to determine average mass of a nucleon.

Again, abundance of carbon-12 isotope is almost equal to 99%. Therefore fluctuation of average atomic weight from 12 amu is very very low.

So, carbon-12 is taken as a standard to determine mass of a nucleon.

Hence atomic mass of carbon-12 is 12 amu.