Binding energy of a nucleus is.

Options

A. energy given to its nucleus during its formation
B. total mass of nucleus converted to energy units
C. loss of energy from the nucleus during its formation
D. total K.E. and P.E. of the nucleons in the nucleus

Answer

### Step-by-Step Solution:

1. **Understanding Binding Energy**:
- Binding energy is the energy required to disassemble a nucleus into its constituent nucleons (protons and neutrons). It can also be viewed as the energy released when nucleons come together to form a nucleus.

2. **Mass of Nucleons**:
- When nucleons (protons and neutrons) are separate, they have a certain total mass, denoted as \( m_1 \).

3. **Mass of the Nucleus**:
- When these nucleons combine to form a nucleus, the nucleus has a different mass, denoted as \( m_2 \). This mass is usually less than the total mass of the individual nucleons due to the binding energy.

4. **Mass Defect**:
- The difference in mass between the separate nucleons and the nucleus is called the mass defect, represented as:
\[ \Delta m = m_1 - m_2 \]

5. **Energy-Mass Equivalence**:
- According to Einstein's theory of relativity, energy and mass are interchangeable. The energy associated with the mass defect can be calculated using the equation:
\[ E = \Delta m \cdot c^2 \]
- Here, \( E \) is the binding energy, \( \Delta m \) is the mass defect, and \( c \) is the speed of light in a vacuum (approximately \( 3 \times 10^8 \) m/s).

6. **Conclusion**:
- The binding energy is the energy released when nucleons bind together to form a nucleus, which corresponds to the loss of energy in the process. Therefore, the correct answer to the question is that the binding energy of a nucleus is the loss of energy from the nucleus during its formation.

### Final Answer:
- The binding energy of a nucleus is the loss of energy from the nucleus during its formation.