One amu is equal to the mass of one ___.
One amu (or atomic mass unit) is approximately equal to the mass of one nucleon (either proton or neutron). In general, the average mass of one proton and one neutron is termed as the amu and this is approximately equal to 1.67 x10^-27 kg.
Since hydrogen has one proton and no neutron, the mass of one hydrogen atom can also be thought as 1 amu. The current definition of amu states that one amu is equal to 1/12th the mass of one carbon-12 atom in its ground state.
Amu is commonly used to state the mass of atoms and molecules. Amu is also sometimes written as Dalton (Da) and is commonly used to report the masses of proteins. For example, hydrogen has a mass of 1 Da and sodium has a mass of 23 Da.
Hope this helps.