12 by definition.
All atomic masses are determined by comparing them to the mass of an atom of carbon12. One atomic mass unit equals one twelfth the mass of an atom of carbon12. That's why its called relativeatomic mass.
The atomic mass of gold is 196,966 599.
The atomic mass (or weight) of silver is 107.8682 amu (atomic mass units)
The approximate mass of an oxygen atom in atomic mass units is 16. Oxygen has an atomic number of 8, which means that its atomic mass is approximately 16 atomic mass units.
Atomic mass units
Atomic mass
The atomic weight of Hg is 200.59 grams per mole.
Cobalt is an atomic mass of 58.93 atomic mass units
The Atomic Mass is the mass (weight) of the element measured in atomic mass units (AMU)
The atomic mass of carbon is approximately 12.01 atomic mass units.
The atomic mass of xenon is about 131.29 atomic mass units.
The atomic mass of arsenic is approximately 74.92 atomic mass units.