One a.m.u. stands for

Options

A. `1/20`(mass of one O-atom)
B. `1/12`(mass of one C-atom)
C. `1/18`(mass of one N-atom)
D. `1/24`(mass of one S-atom)

Answer

To solve the question "One a.m.u. stands for," we can break down the information provided in the video transcript step by step.

### Step-by-Step Solution:

1. **Understanding the Term "a.m.u."**:
- The abbreviation "a.m.u." stands for "Atomic Mass Unit." This is a standard unit used to measure the mass of atoms and molecules.

2. **Definition of Atomic Mass Unit**:
- An atomic mass unit is defined as one twelfth (1/12) of the mass of a carbon-12 atom. This means that the atomic mass unit is a way to express the mass of particles in a way that is convenient for atomic and molecular scales.

3. **Relation to Protons and Neutrons**:
- The atomic mass unit is essentially based on the average mass of protons and neutrons, which are the primary constituents of atomic nuclei.

4. **Value of 1 a.m.u.**:
- The value of 1 a.m.u. can be expressed in kilograms. Specifically, 1 a.m.u. is approximately equal to \( 1.66 \times 10^{-27} \) kg. This is derived from the mass of the carbon atom and the definition of the atomic mass unit.

5. **Conclusion**:
- Therefore, the answer to the question "One a.m.u. stands for" is that it stands for "Atomic Mass Unit."

### Final Answer:
One a.m.u. stands for Atomic Mass Unit.