HgO is prepared by two different methods: one shows yellow colour while the other shows red colour. The difference in colour is due to difference in

Options

A. electronic d-d transitions
B. particle size
C. Frenkel defect
D. Schottkey defect

Answer

To determine the reason for the difference in color of mercury oxide (HgO) prepared by two different methods, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Mercury Oxide (HgO)**:
- Mercury oxide can exist in two forms based on its preparation method: one form appears yellow and the other appears red.

2. **Identifying the Ions in HgO**:
- In both forms, mercury exists as the Hg²⁺ ion. The electronic configuration of Hg²⁺ is:
\[ \text{Hg}^{2+}: [Xe] 4f^{14} 5d^{10} 6s^2 \]
- This configuration shows that the d-orbitals are completely filled.

3. **Analyzing Color Differences**:
- The color difference in solids often arises due to variations in particle size or structural differences. In this case, the yellow and red colors of HgO are attributed to the differences in particle size.

4. **Particle Size and Color**:
- In bulk, mercury oxide shows yellow color when the particles are larger and red color when the particles are smaller. This phenomenon is due to the way light interacts with the different sizes of particles, leading to different absorption and scattering of light.

5. **Eliminating Other Options**:
- **DD Transition**: Since Hg²⁺ has a completely filled d-orbital, d-d transitions are not possible, which rules out color changes due to electronic transitions.
- **Defects**: Frankel and Schottky defects do not explain the color differences observed in this case, as they pertain to the arrangement of ions rather than particle size.

6. **Conclusion**:
- The difference in color of HgO (yellow vs. red) is primarily due to the difference in particle size resulting from the method of preparation.

### Final Answer:
The difference in color of HgO is due to the difference in particle size.

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