A metal which does not react with nitrogen is :

Options

A. `Li`
B. `K`
C. `Ca`
D. `Mg`

Answer

To determine which metal does not react with nitrogen, we can analyze the reactivity of various metals with nitrogen and identify the one that remains unreactive.

### Step-by-Step Solution:

1. **Identify Metals in the s-Block:**
The s-block elements include alkali metals (Group 1) and alkaline earth metals (Group 2). We will focus on these metals to see how they react with nitrogen.

2. **Reactions with Nitrogen:**
- **Lithium (Li):** Lithium reacts with nitrogen to form lithium nitride (Li₃N).
- **Calcium (Ca):** Calcium reacts with nitrogen to form calcium nitride (Ca₃N₂).
- **Magnesium (Mg):** Magnesium also reacts with nitrogen to form magnesium nitride (Mg₃N₂).
- **Potassium (K):** Potassium typically does not react with nitrogen under normal conditions.

3. **Reason for Potassium's Inactivity:**
The reason potassium does not react with nitrogen is due to its lattice energy. The lattice energy of potassium is not high enough to overcome the bond energy of nitrogen (N≡N). This is because the potassium ion (K⁺) has a larger size and lower charge compared to other cations like Li⁺, which makes it less effective in forming stable nitride compounds.

4. **Conclusion:**
Based on the analysis, the metal that does not react with nitrogen is **Potassium (K)**.

### Final Answer:
The metal which does not react with nitrogen is **Potassium (K)**.

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