Which of the following is not present in mineral

Options

A. `KNO_(3)`
B. `CaCO_(3)`
C. NaCl
D. CaO

Answer

To determine which of the following substances is not a mineral, we need to analyze each option provided in the question.

1. **Identify each substance**:
- **Nitre (KNO3)**: Nitre, also known as potassium nitrate, is indeed a mineral that occurs naturally.
- **Calcium Carbonate (CaCO3)**: This is a common mineral known as calcite, which is found in many geological formations.
- **Sodium Chloride (NaCl)**: This is commonly known as salt and occurs naturally as the mineral halite.
- **Calcium Oxide (CaO)**: This is known as quicklime and is not considered a mineral; it is a metal oxide that is typically produced from the thermal decomposition of limestone.

2. **Determine which is not a mineral**:
- Among the options, **CaO (Calcium Oxide)** is not classified as a mineral because it is a product of chemical processes and does not occur naturally in a crystalline form.

3. **Conclusion**:
- Therefore, the correct answer to the question "Which of the following is not present in mineral?" is **CaO (Calcium Oxide)**.

### Final Answer:
CaO (Calcium Oxide) is not a mineral.