Number of oxide ores out of the following are:
Cuprite, Galena, Cassiterite, Magnetite, Bauxite, Carnallite, Calamine

Answer

To determine the number of oxide ores from the given list, we will analyze each substance based on its chemical composition and classification as an oxide ore.

1. **Cuprite (Cu2O)**:
- Cuprite is composed of copper and oxygen. Its formula is Cu2O, which indicates that it is an oxide ore.
- **Conclusion**: Cuprite is an oxide ore.

2. **Galena (PbS)**:
- Galena is composed of lead and sulfur. Its formula is PbS, indicating that it is a sulfide ore, not an oxide ore.
- **Conclusion**: Galena is not an oxide ore.

3. **Cassiterite (SnO2)**:
- Cassiterite is composed of tin and oxygen. Its formula is SnO2, which shows that it is an oxide ore.
- **Conclusion**: Cassiterite is an oxide ore.

4. **Magnetite (Fe3O4)**:
- Magnetite is composed of iron and oxygen. Its formula is Fe3O4, confirming that it is an oxide ore.
- **Conclusion**: Magnetite is an oxide ore.

5. **Bauxite (Al2O3·2H2O)**:
- Bauxite is primarily composed of aluminum oxide (Al2O3) and water. Since it contains aluminum oxide, it is classified as an oxide ore.
- **Conclusion**: Bauxite is an oxide ore.

6. **Carnallite (KMgCl3·6H2O)**:
- Carnallite is composed of potassium, magnesium, chlorine, and water. It does not contain oxygen in the form of an oxide and is therefore not an oxide ore.
- **Conclusion**: Carnallite is not an oxide ore.

7. **Calamine (ZnCO3)**:
- Calamine is primarily composed of zinc carbonate. While it contains zinc, it does not have oxygen in the form of an oxide and is classified as a carbonate ore.
- **Conclusion**: Calamine is not an oxide ore.

Now, summarizing the findings:
- Oxide Ores: Cuprite, Cassiterite, Magnetite, Bauxite
- Non-Oxide Ores: Galena, Carnallite, Calamine

**Total Number of Oxide Ores**: 4

### Summary of Steps:
1. Identify the chemical formula of each ore.
2. Classify each ore as either an oxide or non-oxide based on its composition.
3. Count the number of ores classified as oxide ores.