Define one atomic mass unit (a.m.u.) .

Answer:

An atomic unit of mass is defined as accurately 1/12 the mass of a carbon-12 atom. The carbon-12 atom has six neutrons and six protons in its nucleus. The atomic unit mass is symbolized as AMU or amu.

1 AMU = Average of the proton rest mass and the neutron rest mass.

1 AMU = 1.67377 x 10 ^-27 kilogram or 1.67377 x 10 ^-24 gram.