Which of the following contain both calcium and magnesium:-

Options

A. Magnetite
B. Calamine
C. Carnalite
D. Dolomite

Explanation

To solve the question of which of the following ores contain both calcium and magnesium, we will analyze each option provided.

### Step-by-Step Solution:

1. **Identify the Ores:**
We have four options to consider:
- A) Magnetite
- B) Calamine
- C) Carnalite
- D) Dolomite

2. **Analyze Option A: Magnetite**
- Magnetite is an ore of iron.
- Its chemical formula is Fe3O4.
- Since it contains only iron and oxygen, it does not contain calcium or magnesium.
- **Conclusion:** Not the answer.

3. **Analyze Option B: Calamine**
- Calamine is an ore of zinc.
- Its chemical formula is ZnCO3.
- This compound contains zinc and carbonate but does not contain calcium or magnesium.
- **Conclusion:** Not the answer.

4. **Analyze Option C: Carnalite**
- Carnalite is an ore of magnesium and potassium.
- Its chemical formula is KMgCl3·6H2O.
- Although it contains magnesium, it does not contain calcium.
- **Conclusion:** Not the answer.

5. **Analyze Option D: Dolomite**
- Dolomite is an ore that contains both calcium and magnesium.
- Its chemical formula is CaMg(CO3)2.
- This compound contains both calcium (Ca) and magnesium (Mg).
- **Conclusion:** This is the correct answer.

### Final Answer:
The ore that contains both calcium and magnesium is **D) Dolomite**.

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