One a.m.u. is equal to

Options

A. `1.66xx10^(-8)` g
B. `1.66xx10^(-4)` g
C. `1.66xx10^(-16)` g
D. `1.66xx10^(-24)` g

Answer

To solve the question "One a.m.u. is equal to", we need to understand the definition and value of one atomic mass unit (a.m.u).

### Step-by-Step Solution:

1. **Definition of a.m.u**:
- One atomic mass unit (a.m.u) is defined as one twelfth (1/12) of the mass of a carbon-12 isotope.

2. **Mass of Carbon-12**:
- The mass of one carbon-12 atom is approximately 12 a.m.u. Therefore, when we take one twelfth of this mass, we get:
\[ \text{Mass of 1 a.m.u} = \frac{1}{12} \times 12 \text{ a.m.u} = 1 \text{ a.m.u} \]

3. **Conversion to Kilograms**:
- The value of 1 a.m.u in kilograms is approximately:
\[ 1 \text{ a.m.u} \approx 1.66 \times 10^{-27} \text{ kg} \]

4. **Conversion to Grams**:
- Since 1 kg = 1000 grams, we can convert the mass from kilograms to grams:
\[ 1 \text{ a.m.u} \approx 1.66 \times 10^{-27} \text{ kg} = 1.66 \times 10^{-24} \text{ grams} \]

5. **Conclusion**:
- Therefore, we conclude that:
\[ \text{1 a.m.u} \approx 1.66 \times 10^{-27} \text{ kg} \quad \text{or} \quad 1.66 \times 10^{-24} \text{ grams} \]

### Final Answer:
1 a.m.u is equal to approximately \( 1.66 \times 10^{-27} \) kg or \( 1.66 \times 10^{-24} \) grams.

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