Which of the following chemical equation represents the formation of colloidal solution

Options

A. `Cu+CuCl_2toCu_2Cl_2`
B. `2Mg+CO_2to2MgO+C`
C. `2HNO_3+3H_2Sto3S+4H_2O+2NO`
D. Both (B) and (C )

Answer

To determine which of the given chemical equations represents the formation of a colloidal solution, we need to analyze each option carefully.

### Step-by-Step Solution:

1. **Understanding Colloidal Solutions**:
A colloidal solution is a mixture where very small particles (typically between 1 nm and 1000 nm) of one substance are dispersed in another substance. These particles are larger than molecules but small enough to remain suspended and not settle out.

2. **Evaluating Option 1**:
The first option is:
\[ \text{Cu} + \text{CuCl}_2 \rightarrow \text{Cu}_2\text{Cl}_2 \]
- Here, we have copper reacting with copper(II) chloride to form copper(I) chloride.
- Copper(I) chloride does not fall within the colloidal range; it is a solid and does not form a colloidal solution.
- **Conclusion**: This option is incorrect.

3. **Evaluating Option 2**:
The second option is:
\[ 2 \text{Mg} + \text{CO}_2 \rightarrow 2 \text{MgO} + \text{C} \]
- In this reaction, magnesium reacts with carbon dioxide to produce magnesium oxide and carbon.
- Both magnesium oxide and carbon do not form colloidal solutions; they are either solid or do not exist in colloidal form in this reaction.
- **Conclusion**: This option is also incorrect.

4. **Evaluating Option 3**:
The third option is:
\[ 2 \text{HNO}_3 + 3 \text{H}_2\text{S} \rightarrow 3 \text{S} + 4 \text{H}_2\text{O} + 2 \text{NO} \]
- In this reaction, hydrogen sulfide reacts with nitric acid to produce sulfur, water, and nitrogen monoxide.
- The sulfur produced can exist in a colloidal form. When sulfur particles aggregate, they can form a colloidal solution, specifically a multi-molecular colloid where many sulfur atoms combine to form larger particles that are still within the colloidal size range.
- **Conclusion**: This option represents the formation of a colloidal solution.

5. **Final Answer**:
The correct option that represents the formation of a colloidal solution is:
\[ 2 \text{HNO}_3 + 3 \text{H}_2\text{S} \rightarrow 3 \text{S} + 4 \text{H}_2\text{O} + 2 \text{NO} \]