Magnesium is present in

Options

A. Haemoglobin
B. Chlorophyll
C. Vitamin `B_(12)`
D. Ascorbic acid.

Answer

**Step-by-Step Solution:**

1. **Identify the Context**: The question asks where magnesium is present. To answer this, we need to look at biological and chemical compounds that contain magnesium.

2. **List Compounds Containing Magnesium**:
- **Hemoglobin**: While hemoglobin primarily contains iron, it is important to note that magnesium is not a central component but may be present in trace amounts.
- **Chlorophyll**: Magnesium is a crucial component of chlorophyll, where it acts as the central atom in its structure.
- **Vitamin B12**: This vitamin, also known as cobalamin, contains cobalt but does not contain magnesium.
- **Ascorbic Acid (Vitamin C)**: This vitamin does not contain magnesium either.

3. **Focus on Chlorophyll**: The most significant presence of magnesium in biological systems is in chlorophyll, where it plays a vital role in photosynthesis.

4. **Conclusion**: Based on the analysis, magnesium is primarily present in chlorophyll.

**Final Answer**: Magnesium is present in chlorophyll.

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