(A): Nitrogen can form pentahalides
(R): Nitrogen does not possess vacant d-orbitals in the valance shell

Options

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

Answer

To analyze the question regarding nitrogen's ability to form pentahalides, we will break down the assertion and reason step by step.

### Step 1: Understanding the Assertion
- **Assertion (A)**: "Nitrogen can form pentahalides."
- **Explanation**: Pentahalides refer to compounds where nitrogen is bonded to five halogen atoms, such as NCl5.

### Step 2: Evaluating the Assertion
- **Analysis**: For nitrogen to form a pentahalide, it would need to undergo a specific type of hybridization. The hybridization required for a compound like NCl5 would be sp³d, which involves the mixing of one s orbital, three p orbitals, and one d orbital.

### Step 3: Understanding the Reason
- **Reason (R)**: "Nitrogen does not possess vacant d-orbitals in the valence shell."
- **Explanation**: The electronic configuration of nitrogen is 1s² 2s² 2p³. This configuration shows that nitrogen has no d orbitals in its valence shell (which consists of the 2s and 2p orbitals).

### Step 4: Evaluating the Reason
- **Analysis**: Since nitrogen lacks d orbitals in its valence shell, it cannot achieve the required hybridization (sp³d) to form pentahalides. Therefore, the reason is true.

### Step 5: Conclusion
- **Final Evaluation**:
- The assertion (A) is false because nitrogen cannot form pentahalides due to the absence of vacant d orbitals.
- The reason (R) is true because nitrogen indeed does not possess vacant d orbitals in its valence shell.

### Final Answer
- The correct conclusion is that Assertion (A) is false, and Reason (R) is true.