Assertion (A): Fluorine exhibites only-1 oxidation number in combined state
Reason R : Fluorine is most electron negative element and d-orbitals absent in it

Options

A. A & R are true, R is correct explanation of A
B. A & R are true, R is not correct explanation of A
C. A is true, but R is false
D. A is false, but R is true

Explanation

To analyze the assertion and reason provided in the question, let's break it down step by step:

### Step 1: Understanding the Assertion
**Assertion (A):** Fluorine exhibits only -1 oxidation number in the combined state.

- **Explanation:** Fluorine is a halogen and is known for its high electronegativity. In compounds, it tends to gain one electron to achieve a stable electronic configuration, which results in a -1 oxidation state. This is true for all of its compounds, as fluorine does not exhibit any other oxidation states.

### Step 2: Understanding the Reason
**Reason (R):** Fluorine is the most electronegative element and d-orbitals are absent in it.

- **Explanation:** Fluorine has an electronegativity value of 3.98 on the Pauling scale, making it the most electronegative element. This high electronegativity means that fluorine has a strong tendency to attract electrons. Additionally, fluorine's electronic configuration is 1s² 2s² 2p⁵, which shows that it does not have any d-orbitals (as d-orbitals start from the third energy level). The absence of d-orbitals means fluorine cannot expand its octet, further supporting its tendency to only exhibit a -1 oxidation state.

### Step 3: Evaluating the Truth of Assertion and Reason
- Both the assertion and reason are true statements.
- The reason correctly explains why fluorine exhibits a -1 oxidation state due to its high electronegativity and the absence of d-orbitals.

### Conclusion
Since both the assertion and reason are true, and the reason provides a correct explanation for the assertion, we conclude that the answer is:

**Answer:** Both Assertion (A) and Reason (R) are true, and R is the correct explanation of A.

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