Which of the following compounds is not yellow coloured ?

Options

A. `K_(3)[Co(NO_(2))_(6)]`
B. `(NH_(4))_(3)["As"(Mo_(3)O_(10))_(4)]`
C. `BaCrO_(4)`
D. `Zn_(2)[Fe(CN)_(6)]`

Answer

To determine which of the given compounds is not yellow in color, we will analyze the color characteristics of each compound based on their chemical composition and the nature of their ligands.

### Step-by-Step Solution:

1. **Identify the Compounds**: We have four compounds to analyze. Let's denote them as:
- Compound A: Barium chromate (BaCrO4)
- Compound B: K3[Co(NO2)6]
- Compound C: Ammonium tetra arsenic molybdate
- Compound D: Zn2[Fe(CN)6]

2. **Analyze Barium Chromate (BaCrO4)**:
- Barium chromate is known for its bright yellow color due to the presence of the chromate ion (CrO4^2-). The yellow color arises from charge transfer phenomena.
- **Conclusion**: Barium chromate is yellow.

3. **Analyze K3[Co(NO2)6]**:
- This compound contains cobalt and nitro ligands. The presence of strong field ligands like NO2 can lead to d-d transitions, which can also result in yellow coloration.
- **Conclusion**: K3[Co(NO2)6] is likely yellow.

4. **Analyze Ammonium Tetra Arsenic Molybdate**:
- This compound also contains strong ligands that can cause d-d transitions, leading to a yellow color.
- **Conclusion**: Ammonium tetra arsenic molybdate is likely yellow.

5. **Analyze Zn2[Fe(CN)6]**:
- This compound contains cyanide (CN^-) ligands, which are strong field ligands. However, the complex formed is known to exhibit a bluish-white color rather than yellow.
- **Conclusion**: Zn2[Fe(CN)6] is not yellow; it is bluish-white.

6. **Final Conclusion**:
- Among the four compounds, the only compound that is not yellow in color is **Zn2[Fe(CN)6]**.

### Answer:
**Zn2[Fe(CN)6] is the compound that is not yellow colored.**