Assertion(A): Group 18 gases exhibit very high ionisation enthalpy.
Reason (R): They have a stable electronic configuration.

Options

A. Both A and R are true and R is the correct explanation of A
B. Both A and R are true but R is NOT the correct explanation of A
C. A is true but R is false
D. A is false and R is True.

Explanation

To analyze the given assertion and reason, we will break down the concepts involved step by step.

### Step 1: Understanding the Assertion
**Assertion (A):** Group 18 gases exhibit very high ionization enthalpy.

- **Explanation:** Group 18 elements, also known as noble gases (e.g., Helium, Neon, Argon, etc.), are characterized by their high ionization enthalpy. Ionization enthalpy is the energy required to remove an electron from an atom in the gaseous state. Noble gases have a complete valence shell, which makes them very stable and resistant to losing electrons.

### Step 2: Understanding the Reason
**Reason (R):** They have a stable electronic configuration.

- **Explanation:** The electronic configuration of noble gases is stable because they have a full outer shell of electrons. For example, Helium has 2 electrons, Neon has 8 electrons, and Argon has 18 electrons in their outermost shell. This stability means that they do not readily lose electrons, which is why a significant amount of energy (high ionization enthalpy) is required to remove an electron.

### Step 3: Connecting Assertion and Reason
- Both the assertion and the reason are true statements. The assertion is correct because noble gases do exhibit high ionization enthalpy, and the reason is also correct because their stable electronic configuration is the underlying reason for this high ionization enthalpy.

### Conclusion
- **Final Statement:** Both the assertion (A) and the reason (R) are true, and the reason correctly explains the assertion.

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