Question

define atomic mass unit ​

Answer 1

atomic mass unit (symbolized AMU or amu) is defined as precisely 1/12 the mass of an atom of carbon-12. The carbon-12 (C-12) atom has six protons and six neutrons in its nucleus. In imprecise terms, one AMU is the average of the proton rest mass and the neutron rest mass.

Answer 2

ATOMIC MASS UNIT ...

a unit of mass used to express atomic and molecular weights, equal to one twelfth of the mass of an atom of carbon-12.