Answer:
The answer is: The twelfth part (1/12) of the mass of an atom, neutral and unbound, of carbon-12.
Step-by-step explanation:
The unit of unified atomic mass - symbol "u" -1 or dalton - symbol "Da" - is a standard unit of mass defined as the twelfth part (1/12) of the mass of an atom, neutral and unbound , of carbon-12, in its fundamental electrical and nuclear state, and is equivalent to 1,660 538 921 (73) × 10-27 kg (value recommended by CODATA).
The answer is: The twelfth part (1/12) of the mass of an atom, neutral and unbound, of carbon-12.