Which of the following is/are oxide ores?

Options

A. Cassiterite
B. Malachite
C. Chromite
D. Dolomite

Explanation

To determine which of the given options are oxide ores, we will analyze each option based on their chemical composition and classification.

### Step-by-Step Solution:

1. **Identify the first option: Cassiterite**
- **Chemical Formula**: SnO2
- **Analysis**: Cassiterite is known as tin stone and contains tin oxide. Since it contains the oxide ion (O^2-), it is classified as an oxide ore.
- **Conclusion**: Cassiterite is an oxide ore.

2. **Identify the second option: Malachite**
- **Chemical Formula**: Cu2CO3(OH)2
- **Analysis**: Malachite is a copper carbonate mineral. It contains carbonate ions (CO3^2-) and hydroxide ions (OH^-), but does not contain oxide ions. Therefore, it does not classify as an oxide ore.
- **Conclusion**: Malachite is not an oxide ore.

3. **Identify the third option: Chromite**
- **Chemical Formula**: FeCr2O4
- **Analysis**: Chromite is a chromium oxide mineral. It contains oxide ions (O^2-), which means it is classified as an oxide ore.
- **Conclusion**: Chromite is an oxide ore.

4. **Identify the fourth option: Dolomite**
- **Chemical Formula**: CaMg(CO3)2
- **Analysis**: Dolomite is a carbonate mineral and contains carbonate ions (CO3^2-). It does not contain oxide ions, so it does not classify as an oxide ore.
- **Conclusion**: Dolomite is not an oxide ore.

### Final Conclusion:
The oxide ores from the given options are:
- **Cassiterite (SnO2)**
- **Chromite (FeCr2O4)**