2  ATOMIC MASSES AND COMPOSITION OF NUCLEUS
The mass of an atom is very small, compared to a kilogram;  for example,
the mass of a carbon atom, 12C, is 1 992647 × 10–26 kg Kilogram is not
a very convenient unit to measure such small quantities Therefore, a
Chapter Thirteen
NUCLEI
Rationalised 2023-24
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Nuclei
different mass unit is used for expressing atomic masses