The number of correctly matched combination is/are
`{:("Ore","Element"),("Chalcopyrite","Cu"),("Limestone","Ca"),("Corundum","Al"),("Magnetite","Fe"),("Pyrolusite","Mn"),("Cassiterite","Zn"),("Cinnabar","Hg"),("Calamine","Ca"),("Siderite","Sn"),("Cerussite","Pb"):}`

Answer

To solve the problem of identifying the number of correctly matched combinations of ores and their respective elements, we will analyze each combination one by one.

### Step-by-Step Solution:

1. **Ore: Chalcopyrite**
- **Formula**: CuFeS₂
- **Main Element**: Copper (Cu)
- **Match**: Correct (Chalcopyrite is primarily a copper ore).

2. **Ore: Limestone**
- **Formula**: CaCO₃
- **Main Element**: Calcium (Ca)
- **Match**: Correct (Limestone contains calcium).

3. **Ore: Corundum**
- **Formula**: Al₂O₃
- **Main Element**: Aluminum (Al)
- **Match**: Correct (Corundum is primarily aluminum oxide).

4. **Ore: Magnetite**
- **Formula**: Fe₃O₄ (or FeO.Fe₂O₃)
- **Main Element**: Iron (Fe)
- **Match**: Correct (Magnetite is an iron ore).

5. **Ore: Pyrolusite**
- **Formula**: MnO₂
- **Main Element**: Manganese (Mn)
- **Match**: Correct (Pyrolusite is primarily manganese).

6. **Ore: Cassiterite**
- **Formula**: SnO₂
- **Main Element**: Tin (Sn)
- **Match**: Incorrect (It is matched with Zinc (Zn), which is wrong).

7. **Ore: Cinnabar**
- **Formula**: HgS
- **Main Element**: Mercury (Hg)
- **Match**: Correct (Cinnabar is primarily mercury).

8. **Ore: Calamine**
- **Formula**: ZnCO₃ (with traces of Fe)
- **Main Element**: Zinc (Zn)
- **Match**: Incorrect (It is matched with Calcium (Ca), which is wrong).

9. **Ore: Siderite**
- **Formula**: FeCO₃
- **Main Element**: Iron (Fe)
- **Match**: Incorrect (It is matched with Tin (Sn), which is wrong).

10. **Ore: Cerussite**
- **Formula**: PbCO₃
- **Main Element**: Lead (Pb)
- **Match**: Correct (Cerussite is primarily lead).

### Summary of Matches:
- Correct Matches: Chalcopyrite, Limestone, Corundum, Magnetite, Pyrolusite, Cinnabar, Cerussite
- Incorrect Matches: Cassiterite, Calamine, Siderite

### Total Correct Matches:
- Total Correct Matches = 7

### Final Answer:
The number of correctly matched combinations is **7**.

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