Binding energy of a nucleus is of the order of:

Options

A. electron volt (eV)
B. kilo electron volt (keV)
C. mega electron volt (MeV)
D. a joule (J)

Explanation

To determine the binding energy of a nucleus, we need to understand what binding energy is and the typical scales associated with it.

### Step-by-Step Solution:

1. **Definition of Binding Energy**:
- Binding energy is the energy required to separate a nucleus into its individual protons and neutrons. It is a measure of the stability of the nucleus.

2. **Understanding Energy Units**:
- Binding energy can be expressed in various units, including electron volts (eV), kilo electron volts (keV), mega electron volts (MeV), and joules (J).
- 1 eV = \(1.6 \times 10^{-19}\) Joules,
- 1 keV = \(10^3\) eV,
- 1 MeV = \(10^6\) eV.

3. **Typical Values of Binding Energy**:
- The binding energy of atomic nuclei typically ranges from a few MeV to several tens of MeV. For example, the binding energy of a helium nucleus is about 28.3 MeV.

4. **Evaluating the Options**:
- Option 1: Electron Volt (eV) - This is too low for nuclear binding energies.
- Option 2: Kilo Electron Volt (keV) - This is still generally lower than typical nuclear binding energies.
- Option 3: Mega Electron Volt (MeV) - This is consistent with the typical values of binding energy observed in nuclei.
- Option 4: Joule - While binding energy can be expressed in joules, it is not a common representation for nuclear binding energy.

5. **Conclusion**:
- Given the typical range of binding energies for nuclei, the correct answer is that the binding energy of a nucleus is of the order of **mega electron volts (MeV)**. Thus, the correct option is **Option 3**.