The colour imparted by `Co(II)` compound to glass is

Options

A. green
B. deep-blue
C. yellow
D. red

Explanation

To determine the color imparted by Co(II) compounds to glass, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Glass Composition**:
- Glass is primarily made from silicates, which are compounds containing silicon and oxygen, often mixed with various metal oxides.

2. **Role of Metal Ions**:
- Different metal ions can impart specific colors to glass. This is due to the electronic transitions of the metal ions when they are in a glass matrix.

3. **Identifying Cobalt(II) Ion**:
- The cobalt ion in question is Co(II), which is cobalt in the +2 oxidation state.

4. **Known Color Imparted by Cobalt(II)**:
- It is established that Co(II) compounds impart a deep blue color to glass. This is a characteristic color associated with cobalt ions in various compounds.

5. **Conclusion**:
- Therefore, the color imparted by Co(II) compounds to glass is deep blue.

### Final Answer:
The color imparted by Co(II) compounds to glass is **deep blue**.

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