Which of the following metals will react directly with nitrogen to form nitride?

Options

A. Na
B. K
C. Cs
D. Li

Answer

To determine which metal reacts directly with nitrogen to form a nitride, we can follow these steps:

### Step 1: Understand the concept of nitrides
Nitrides are compounds formed when metals react with nitrogen. Not all metals can react directly with nitrogen; typically, only certain reactive metals can do so.

### Step 2: Identify reactive metals
Among the metals, alkali metals and some alkaline earth metals are known for their high reactivity. Lithium (Li), sodium (Na), potassium (K), and magnesium (Mg) are examples of such metals.

### Step 3: Analyze the reactivity of metals with nitrogen
- **Lithium (Li)**: Lithium is known to react directly with nitrogen to form lithium nitride (Li3N) without requiring any special conditions.
- **Sodium (Na)**: Sodium can also react with nitrogen, but it is less reactive compared to lithium.
- **Potassium (K)**: Potassium is highly reactive but typically forms nitrides under specific conditions.
- **Magnesium (Mg)**: Magnesium can react with nitrogen, but it usually requires higher temperatures to form magnesium nitride (Mg3N2).

### Step 4: Conclusion
Based on the reactivity of the metals with nitrogen, lithium is the most reactive and can directly form lithium nitride without any special conditions. Therefore, the correct answer is lithium.

### Final Answer
The metal that reacts directly with nitrogen to form nitride is **Lithium (Li)**.

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