When black copper oxide placed in a beaker is treated with dilute HCl is colour changes to

Options

A. white
B. dark red
C. bluish green
D. no change .

Answer

To solve the question of what color change occurs when black copper oxide is treated with dilute hydrochloric acid (HCl), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactants in this reaction are black copper oxide (CuO) and dilute hydrochloric acid (HCl).

2. **Determine the Nature of Copper Oxide**:
- Copper oxide (CuO) is a basic oxide because it is a metal oxide.

3. **Write the Reaction**:
- When copper oxide reacts with hydrochloric acid, a chemical reaction occurs:
\[ \text{CuO (s)} + 2 \text{HCl (aq)} \rightarrow \text{CuCl}_2 \text{(aq)} + \text{H}_2\text{O (l)} \]
- In this reaction, copper oxide reacts with hydrochloric acid to form cupric chloride (CuCl₂) and water (H₂O).

4. **Identify the Color Change**:
- Initially, copper oxide is black in color. When it reacts with dilute hydrochloric acid, it forms cupric chloride, which is typically blueish-green in color.

5. **Conclusion**:
- Therefore, the color changes from black (CuO) to blueish-green (CuCl₂) when black copper oxide is treated with dilute HCl.

### Final Answer:
The color changes from black to blueish-green.

---