Chlorophyll is a compound of calcium.

Explanation

**Step-by-Step Solution:**

1. **Understanding Chlorophyll**: Chlorophyll is a green pigment found in plants that is essential for photosynthesis. It is responsible for absorbing light energy.

2. **Identifying the Central Ion**: The central ion in chlorophyll is not calcium; it is actually magnesium (Mg). This is a key point because it determines the composition of chlorophyll.

3. **Analyzing the Composition**: Chlorophyll has a porphyrin ring structure, which includes a central magnesium ion surrounded by nitrogen atoms from the pyrrole groups. This structure is crucial for its function in photosynthesis.

4. **Conclusion**: Since chlorophyll contains magnesium as its central ion, the statement "Chlorophyll is a compound of calcium" is incorrect. Therefore, chlorophyll is a compound of magnesium.

**Final Statement**: The statement that chlorophyll is a compound of calcium is false; chlorophyll actually contains magnesium.

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