Which of the following is/are pure substance(s)?

Options

A. CuSO4.5H2O
B. Brass
C. Diamond
D. All of these

Answer

To determine which of the given options are pure substances, we need to understand the definition of a pure substance. A pure substance is a material that has a constant composition and consistent properties throughout. This can include elements and compounds, but not mixtures or alloys.

### Step-by-Step Solution:

1. **Identify the Options**: We need to analyze each option provided in the question to determine if it is a pure substance.

2. **Evaluate Copper Sulfate (CuSO₄·5H₂O)**:
- Copper sulfate is a compound, and specifically, the hydrated form (CuSO₄·5H₂O) indicates that it has a fixed composition of copper, sulfur, oxygen, and water.
- Since it is a compound with a definite composition, **Copper Sulfate is a pure substance**.

3. **Evaluate Brass**:
- Brass is an alloy, which means it is a mixture of metals (typically copper and zinc).
- The composition of brass can vary, meaning it does not have a fixed composition.
- Therefore, **Brass is not a pure substance**.

4. **Evaluate Diamond**:
- Diamond is a form of carbon, which is an element.
- Since it consists solely of carbon atoms and has a consistent composition, **Diamond is a pure substance**.

5. **Conclusion**:
- From the evaluations, we find that Copper Sulfate and Diamond are pure substances, while Brass is not.
- Therefore, the correct options are **Copper Sulfate and Diamond**.

### Final Answer:
The pure substances among the options are **Copper Sulfate (CuSO₄·5H₂O) and Diamond**.

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