Colour of compounds occurs due to phenomenon of polarisation, charge transfer, d-d transition and H.O.M.O.L.U.M.O transition. Most of the transition metal transition metal complex compound are coloured either due to d-d electrons transition or charge transfer and ionic compounds are coloured due to polarisation of anion. Q. If `MCl_(4)` salt is white, then comment on colour of its iodine salt.

Options

A. Coloured
B. White
C. May be or coloured
D. Black

Answer

To determine the color of the iodine salt \( MI_4 \) given that \( MCl_4 \) is white, we can analyze the situation step by step.

### Step 1: Understand the nature of \( MCl_4 \)
The compound \( MCl_4 \) is described as white. This suggests that it does not absorb visible light, meaning that there are no electronic transitions occurring that would lead to color. In transition metal complexes, the color often arises from d-d transitions or charge transfer processes.

**Hint:** The color of a compound is often related to the electronic transitions of its metal ion.

### Step 2: Consider the role of the anion
In \( MCl_4 \), the chloride ions (\( Cl^- \)) are present. Chloride ions are typically weak field ligands, which means they do not cause significant splitting of the d-orbitals in the metal ion. As a result, the d-d transitions are not favored, leading to the white color of \( MCl_4 \).

**Hint:** The type of ligands can influence the electronic transitions and thus the color of the compound.

### Step 3: Analyze \( MI_4 \)
Now, when we consider the iodine salt \( MI_4 \), we have to think about the nature of the iodide ions (\( I^- \)). Iodide ions are larger and also considered weak field ligands, similar to chloride ions. However, they can sometimes lead to different electronic environments due to their size and the nature of the metal ion.

**Hint:** Different anions can lead to different electronic environments even if they are weak field ligands.

### Step 4: Conclusion on the color of \( MI_4 \)
Since \( MCl_4 \) is white, it indicates that there are no significant electronic transitions occurring. The iodine salt \( MI_4 \) could potentially be colored or colorless, depending on the specific metal ion \( M \) and its electronic configuration. Without additional information about the metal ion, we cannot definitively conclude the color of \( MI_4 \).

**Hint:** The color of a compound can vary widely based on the metal ion and its oxidation state, even with the same type of ligands.

### Final Answer:
The iodine salt \( MI_4 \) may be colored or may be colorless, similar to \( MCl_4 \).