Which of the following compounds contain boron?

Options

A. Borax
B. Colemanite
C. Feldspar
D. kernite

Answer

To determine which of the given compounds contain boron, we will analyze each compound listed in the options.

### Step-by-Step Solution:

1. **Identify the Compounds**:
- The compounds given are:
1. Borax
2. Columninite
3. Feldspar
4. Kernite

2. **Analyze Borax**:
- Borax is also known as sodium borate.
- Its chemical formula is Na₂B₄O₇·10H₂O.
- Since it contains the element 'B' in its formula (specifically B₄), we conclude that borax contains boron.

3. **Analyze Columninite**:
- Columninite is a secondary mineral formed from the alteration of borax and eulexite.
- Its chemical formula is Ca₂B₆O₁₁·5H₂O.
- The presence of 'B' in its formula (specifically B₆) indicates that columninite also contains boron.

4. **Analyze Feldspar**:
- Feldspar has a general chemical formula of the type XAlSi₃O₈, where X can be potassium (K) or sodium (Na).
- There is no 'B' present in this formula, which means feldspar does not contain boron.

5. **Analyze Kernite**:
- Kernite is a hydrated sodium borate hydroxide mineral.
- Its chemical formula is Na₂B₄O₆(OH)·3H₂O.
- The presence of 'B' in its formula (specifically B₄) confirms that kernite contains boron.

6. **Conclusion**:
- The compounds that contain boron are:
- Borax
- Columninite
- Kernite
- Feldspar does not contain boron.

### Final Answer:
The compounds that contain boron are:
- Borax
- Columninite
- Kernite