Which of the following are coloured?

Options

A. `CuSO_(4).5H_(2)O`
B. `NiSO_(4).7H_(2)O`
C. `CaCl_(2)`
D. `CO(NO_(3))_(2)`

Answer

To determine which of the given compounds are colored, we will analyze each compound based on their composition and the presence of water of crystallization.

### Step-by-Step Solution:

1. **Identify the Compounds**: We have the following compounds to analyze:
- Copper sulfate pentahydrate (CuSO4·5H2O)
- Nickel sulfate heptahydrate (NiSO4·7H2O)
- Calcium chloride (CaCl2)
- Calcium nitrate (Ca(NO3)2)

2. **Analyze Copper Sulfate Pentahydrate (CuSO4·5H2O)**:
- This compound contains water of crystallization.
- Copper sulfate is known to be blue in color due to the presence of Cu²⁺ ions.
- **Conclusion**: CuSO4·5H2O is colored (blue).

3. **Analyze Nickel Sulfate Heptahydrate (NiSO4·7H2O)**:
- This compound also contains water of crystallization.
- Nickel sulfate is green in color due to the presence of Ni²⁺ ions.
- **Conclusion**: NiSO4·7H2O is colored (green).

4. **Analyze Calcium Chloride (CaCl2)**:
- Calcium chloride is typically an anhydrous salt.
- It does not contain water of crystallization and is colorless.
- **Conclusion**: CaCl2 is colorless.

5. **Analyze Calcium Nitrate (Ca(NO3)2)**:
- Calcium nitrate is also an anhydrous salt.
- It does not contain water of crystallization and is colorless.
- **Conclusion**: Ca(NO3)2 is colorless.

6. **Final Summary**:
- Colored compounds: CuSO4·5H2O (blue) and NiSO4·7H2O (green).
- Colorless compounds: CaCl2 and Ca(NO3)2.

### Final Answer:
- The colored compounds are **CuSO4·5H2O** and **NiSO4·7H2O**.