All form ideal solution except

Options

A. `C_(2)H_(5)I and C_(2)H_(5)OH`
B. `C_(6)H_(5)Cl and C_(6)H_(5)Br`
C. `C_(2)H_(5)Cl and C_(2)H_(5)I`
D. `C_(6)H_(6) and C_(6)H_(6) and C_(6)H_(5)Ch_(3)`

Explanation

To determine which of the given solutions does not form an ideal solution, we need to analyze the chemical similarities and differences between the pairs of substances provided. An ideal solution is formed when the components are chemically similar, allowing for uniform interactions and properties.

### Step-by-Step Solution:

1. **Identify the Given Options:**
- Option 1: Ethyl iodide (C2H5I) and Ethyl alcohol (C2H5OH)
- Option 2: Chlorobenzene (C6H5Cl) and Bromobenzene (C6H5Br)
- Option 3: Ethyl chloride (C2H5Cl) and Ethyl iodide (C2H5I)
- Option 4: Benzene (C6H6) and Toluene (C6H5CH3)

2. **Analyze Option 1: Ethyl Iodide and Ethyl Alcohol**
- Ethyl iodide is a halide, while ethyl alcohol is an alcohol.
- These two have different functional groups and chemical properties, making them chemically dissimilar.
- **Conclusion:** This pair is likely to form a non-ideal solution.

3. **Analyze Option 2: Chlorobenzene and Bromobenzene**
- Both compounds are halogenated derivatives of benzene.
- They have similar structures and properties, indicating they can mix well.
- **Conclusion:** This pair can form an ideal solution.

4. **Analyze Option 3: Ethyl Chloride and Ethyl Iodide**
- Both are halides and have similar structures.
- They belong to the same family and have comparable chemical properties.
- **Conclusion:** This pair can form an ideal solution.

5. **Analyze Option 4: Benzene and Toluene**
- Benzene and toluene are both aromatic hydrocarbons with similar structures.
- They can mix uniformly due to their chemical similarities.
- **Conclusion:** This pair can form an ideal solution.

6. **Final Conclusion:**
- Among all the options analyzed, only **Option 1 (Ethyl iodide and Ethyl alcohol)** is chemically dissimilar and will form a non-ideal solution.

### Final Answer:
**Option 1: Ethyl iodide and Ethyl alcohol do not form an ideal solution.**