Which compound has coloured aqueous solution

Options

A. `Zn(NO_(3))_(2)`
B. `LiNO_(3)`
C. `Co(NO_(3))_(2)`
D. `Ba(NO_(3))_(2)`

Answer

To determine which compound has a colored aqueous solution, we need to analyze each option based on the presence of d-d transitions in the metal ions present in the compounds. D-d transitions are responsible for the color in transition metal compounds.

### Step-by-Step Solution:

1. **Identify the Compounds**: The options given are:
- (1) Jaden NO3 whole twice
- (2) Li NO3
- (3) CO NO3 whole twice
- (4) BA NO3 whole twice

2. **Analyze Jaden NO3 (Jaden(II) Nitrate)**:
- Jaden (or Lead) does not have d-electrons that can undergo d-d transitions in its common oxidation states. Therefore, it does not exhibit color in solution.
- **Conclusion**: Colorless.

3. **Analyze Li NO3 (Lithium Nitrate)**:
- Lithium is an alkali metal and does not have d-electrons. Hence, it does not show any color in solution.
- **Conclusion**: Colorless.

4. **Analyze CO NO3 (Cobalt(II) Nitrate)**:
- Cobalt is a transition metal and has d-electrons. In its +2 oxidation state, cobalt can undergo d-d transitions, which results in the absorption of certain wavelengths of light, giving it a colored appearance in solution.
- **Conclusion**: Colored.

5. **Analyze BA NO3 (Barium Nitrate)**:
- Barium is an alkaline earth metal and does not have d-electrons. Therefore, it does not exhibit any color in solution.
- **Conclusion**: Colorless.

6. **Final Conclusion**:
- Among the given options, only Cobalt(II) Nitrate (CO NO3 whole twice) has a colored aqueous solution.

### Answer:
The compound with a colored aqueous solution is **CO NO3 whole twice (Cobalt(II) Nitrate)**.

---