Question

ddefine atomic mass ​

Answer 1

The atomic mass is the mass of an atom. Its unit is the unified atomic mass units where 1 unified atomic mass unit is defined as ​¹⁄₁₂ of the mass of a single carbon-12 atom, at rest.

Answer 2

Atomic mass of an element is the relative mass of its atom as compared with the mass of carbon 12 atom.