What is one a.m.u. or one 'u'?

Explanation

To understand what one atomic mass unit (amu) or one unified atomic mass unit (u) is, we can break it down into a few steps:

### Step-by-Step Solution:

1. **Definition of Atomic Mass Unit (amu)**:
- The atomic mass unit (amu) is a standard unit of mass that quantifies mass on an atomic or molecular scale.
- It is also referred to as the unified atomic mass unit (u).

...