Question

what is atomic mass unit? What does it mean that 1/12th the mass of carbon 12

Answer 1

It is expressed as a multiple of one-twelfth the mass of the carbon-12 atom, 1.992646547 × 10−23 gram, which is assigned an atomic mass of 12 units. In this scale 1 atomic mass unit (amu) corresponds to 1.660539040 × 10−24 gram.