Ionisation energy depends upon:

Options

A. Principle qunatum number
B. Azimuthal quantum number
C. Magnetic quantum number
D. (1) & (2) both

Answer

### Step-by-Step Solution:

1. **Understanding Ionization Energy**:
- Ionization energy is defined as the minimum amount of energy required to remove the most loosely bound electron from an atom or molecule.

2. **Factors Affecting Ionization Energy**:
- Ionization energy depends on several factors, primarily:
- **Principal Quantum Number (n)**: This indicates the energy level of the electron. As the principal quantum number increases, the distance of the electron from the nucleus increases, leading to a decrease in ionization energy.
- **Azimuthal Quantum Number (l)**: This represents the subshell in which the electron resides. Electrons in subshells with higher angular momentum (higher l values) are generally held less tightly by the nucleus, which can affect ionization energy.

3. **Quantum Numbers**:
- The principal quantum number (n) and azimuthal quantum number (l) are crucial in determining the energy levels and the stability of electrons in an atom.
- The magnetic quantum number (m) does not directly affect ionization energy since it describes the orientation of the orbital rather than the energy associated with removing an electron.

4. **Conclusion**:
- Based on the analysis, we conclude that ionization energy depends on the principal quantum number and the azimuthal quantum number. Therefore, the correct answer is that it depends on options A and B.

5. **Final Answer**:
- The correct option is D, which states that ionization energy depends on the principal quantum number and the azimuthal quantum number.