EVERYDAY SCIENCE

Detailed explanation-1: -Carbon-12 is considered a reference for all atomic mass calculations. Thus, the mass of any isotope of any element is expressed in terms of the 12C standard of AMU.

Detailed explanation-2: -Assertion :One atomic mass unit is defined as one twelfth of the mass of one carbon-12 atom. Reason: Carbon-12 isotope is the most abundant isotope of carbon and has been chosen as standard.

Detailed explanation-3: -On the periodic table the mass of carbon is reported as 12.01 amu. This is the average atomic mass of carbon. No single carbon atom has a mass of 12.01 amu, but in a handful of C atoms the average mass of the carbon atoms is 12.01 amu.

Detailed explanation-4: -Since the chemical atomic weights of carbon 12 are almost equal to those of the natural mix of oxygen, it was selected as the standard. Since no other nuclide has an identical whole-number mass on this scale except carbon-12. Six protons, six neutrons, and six electrons make up carbon-12.

Detailed explanation-5: -(iii) IUPAC adopted one-twelfth of the mass of carbon (C12) isotope as the reference atom.