When electric current is passed through a conducting solution, there is a change of colour of the solution. This indicates :

Options

A. the chemical effect of current.
B. the heating effect of current
C. the magnetic effect of current.
D. the lightning effect of current.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the change of color in a conducting solution when electric current is passed through it. We need to determine what this change indicates.

2. **Identifying the Effects of Electric Current**: Electric current can have several effects when passed through a solution:
- **Chemical Effect**: This involves chemical reactions that can change the composition of the solution, which may include a change in color.
- **Heating Effect**: This is the generation of heat due to resistance in the solution, which does not necessarily change the color.
- **Magnetic Effect**: This involves the influence of magnetic fields created by electric currents, which does not relate to color change.
- **Lightning Effect**: This is not a standard term in the context of electric current and solutions.

3. **Analyzing the Color Change**: When the electric current passes through the conducting solution, it can cause ions in the solution to react chemically. This reaction can lead to the formation of new substances, which may have different colors compared to the original solution.

4. **Conclusion**: Since the question specifically mentions a change in color, it indicates that a chemical reaction is occurring due to the passage of electric current. Therefore, the change in color of the solution indicates the **chemical effect of current**.

5. **Final Answer**: The change of color of the solution indicates the **chemical effect of current**.

---