Which of the following metals forms grignard reagent?

Options

A. Magnesium
B. Calcium
C. Barium
D. Strontium

Answer

To determine which of the following metals forms Grignard reagents, we need to analyze the provided options: magnesium, calcium, barium, and strontium.

### Step-by-Step Solution:

1. **Understanding Grignard Reagents**: Grignard reagents are organomagnesium compounds with the general formula R-MgX, where R is an alkyl or aryl group and X is a halogen. They are formed by the reaction of magnesium with organic halides.

2. **Identifying the Metal**: The key metal involved in the formation of Grignard reagents is magnesium. It is known for its ability to form stable Grignard reagents due to its unique properties.

3. **Properties of Magnesium**: Magnesium is a Group 2 element that has a relatively small atomic size compared to other alkaline earth metals. This smaller size allows magnesium to effectively bond with larger alkyl groups, forming stable Grignard reagents.

4. **Comparison with Other Metals**:
- **Calcium, Barium, and Strontium**: These metals, while also belonging to Group 2, have larger atomic sizes and lower effective nuclear charge compared to magnesium. This makes it difficult for them to stabilize the alkyl groups in the Grignard reagent structure.

5. **Conclusion**: Based on the properties and behavior of these metals, only magnesium can effectively form Grignard reagents. Therefore, the correct answer is:
- **Option A: Magnesium**