Which of the following does not affect the ionisation potential of the atom ?

Options

A. Nuclear charge
B. electron neutrality with protons
C. penetration effect
D. atomic size.

Answer

To determine which of the following factors does not affect the ionization potential of an atom, let's analyze each option step by step:

### Step 1: Understand Ionization Potential
Ionization potential (or ionization energy) is the amount of energy required to remove the outermost electron from an atom. Factors affecting ionization potential include nuclear charge, electron configuration, atomic size, and penetration effect.

### Step 2: Analyze Each Option
1. **Nuclear Charge**: The nuclear charge is the total charge of the nucleus due to protons. A higher nuclear charge increases the attraction between the nucleus and the outermost electron, thus increasing ionization potential. Therefore, this option affects ionization potential.

2. **Electron Neutrality with Protons**: This refers to the balance between the number of protons and electrons in an atom. While this balance is essential for the stability of the atom, it does not directly influence the energy required to remove an electron. Thus, this option does not affect ionization potential.

3. **Penetration Effect**: This describes how close an electron can get to the nucleus. Electrons in s-orbitals have a higher probability of being closer to the nucleus compared to p-orbitals. This proximity increases the attraction and thus the ionization potential. Therefore, this option affects ionization potential.

4. **Atomic Size**: As atomic size decreases (moving across a period), the nuclear charge increases, leading to a stronger attraction between the nucleus and the outermost electron, which increases ionization potential. Hence, this option also affects ionization potential.

### Conclusion
From the analysis, the factor that does not affect the ionization potential of the atom is **Electron Neutrality with Protons**.

### Final Answer
**Electron Neutrality with Protons** does not affect the ionization potential of the atom.

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