The colour of the borax bead is due to the formation of a/an

Options

A. Glass like metal metaborate bead
B. Hard boric oxide crystal
C. Opaque metal hexaborate bead
D. Glass-like metal orthoborate bead

Answer

To solve the question regarding the color of the borax bead, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Borax Bead Formation**:
- When borax (sodium tetraborate) is heated, it loses water molecules. This process is known as dehydration.

2. **Transformation into a Glass-like State**:
- Upon further heating, the borax melts and forms a transparent liquid. When cooled, this liquid solidifies into a glass-like structure.

3. **Role of Transition Metals**:
- The color of the borax bead is influenced by the presence of transition metals. These metals can impart various colors to the bead due to their electronic transitions.

4. **Color Characteristics**:
- Transition metals have unique color characteristics based on their oxidation states and the ligands surrounding them. The color observed in the borax bead is due to the formation of colored complexes with these transition metals.

5. **Conclusion**:
- Therefore, the color of the borax bead is due to the formation of a colored complex involving transition metals, which can be referred to as a "metallate" or "metal complex."

### Final Answer:
The color of the borax bead is due to the formation of a metallate (or metal complex) involving transition metals.

---