Which one of the following elements has the highest ionisation energy?

Options

A. `[Ne] 3s^(2)3p^(1)`
B. `[Ne]3s^(2)3p^(3)`
C. `[Ne]3s^(2)3p^(2)`
D. `[Ar] 3d^(10) 4s^(2) 4p^(2)`

Explanation

To determine which element has the highest ionization energy among the given options, we need to analyze the electronic configurations of the elements listed and understand the concept of ionization energy.

### Step-by-Step Solution:

1. **Identify the Elements and Their Electronic Configurations**:
- **Option 1**: Neon (Ne) - 1s² 2s² 2p⁶ (Atomic number 10)
- **Option 2**: Phosphorus (P) - 1s² 2s² 2p⁶ 3s² 3p³ (Atomic number 15)
- **Option 3**: Silicon (Si) - 1s² 2s² 2p⁶ 3s² 3p² (Atomic number 14)
- **Option 4**: Argon (Ar) - 1s² 2s² 2p⁶ 3s² 3p⁶ (Atomic number 18)

2. **Understanding Ionization Energy**:
- Ionization energy is the energy required to remove an electron from an atom in the gas phase.
- Generally, ionization energy increases across a period (from left to right) and decreases down a group (from top to bottom) in the periodic table.

3. **Analyze the Options**:
- **Neon**: As a noble gas, it has a complete outer shell and thus has a very high ionization energy.
- **Phosphorus**: Has a half-filled p subshell (3p³), which is relatively stable but not as stable as a noble gas.
- **Silicon**: Has 3p², which is less stable than phosphorus.
- **Argon**: Another noble gas with a complete outer shell, but it is lower in ionization energy compared to Neon.

4. **Comparing the Ionization Energies**:
- Neon has a complete outer shell, making it very stable and requiring a lot of energy to remove an electron.
- Argon also has a complete outer shell but is further down the group, meaning it has lower ionization energy compared to Neon.
- Phosphorus and Silicon have lower ionization energies compared to Neon and Argon due to their incomplete outer shells.

5. **Conclusion**:
- Among the given options, **Neon** has the highest ionization energy due to its stable electronic configuration as a noble gas.

### Final Answer:
The element with the highest ionization energy is **Neon (Option 1)**.

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