Which of the following is a wrong description of binding energy of a nucleus?

Options

A. It is the energy required to break a nucleus into its constituent nucleons
B. It is the energy made available when free nucleons combine to form a nucleus
C. It is the sum of the rest mass energies of its nucleons minus the rest mass energy of the nucleus
D. None of the above

Explanation

To determine which of the following descriptions of binding energy of a nucleus is incorrect, we will analyze each statement step by step.

### Step 1: Understand Binding Energy
Binding energy is defined as the energy required to separate a nucleus into its constituent nucleons (protons and neutrons). It can also be described as the energy released when nucleons combine to form a nucleus.

**Hint:** Remember that binding energy is related to the stability of the nucleus; a higher binding energy means a more stable nucleus.

### Step 2: Analyze Each Statement
1. **Statement 1:** "It is the energy required to break a nucleus into its constituent nucleons."
- This statement is correct because breaking a nucleus requires energy input, which is the definition of binding energy.

**Hint:** Think about the process of breaking bonds; energy is needed to overcome the forces holding the nucleons together.

2. **Statement 2:** "It is energy made available when free nucleons combine to form a nucleus."
- This statement is also correct. When nucleons combine, energy is released, indicating that the formation of the nucleus is an exothermic process.

**Hint:** Consider the energy dynamics of formation versus breaking; formation releases energy.

3. **Statement 3:** "It is a sum of the rest mass energy of its nucleons minus the rest mass energy of the nucleus."
- This statement is true as well. The mass defect (the difference between the total mass of the individual nucleons and the mass of the nucleus) is directly related to the binding energy.

**Hint:** Recall the mass-energy equivalence principle (E=mc²) and how mass defect translates to energy.

4. **Statement 4:** "None of these is an incorrect explanation of binding energy."
- This statement implies that all previous statements are correct. However, if we are looking for an incorrect description, we must identify if any of the first three statements are wrong.

**Hint:** Review the definitions and concepts of binding energy carefully to identify any inconsistencies.

### Conclusion
After analyzing all statements, we find that all three descriptions of binding energy are correct. Therefore, the statement that claims "none of these is an incorrect explanation of binding energy" is the only one that can be considered incorrect in the context of the question.

### Final Answer
The wrong description of binding energy of a nucleus is: **Option 4: None of these is an incorrect explanation of binding energy.**