Which pair(s) of liquids on mixing is/are expected to show no net volume change and no heat effect?

Options

A. Acetone and ethanol
B. Chlorobenzene and bromobenzene
C. Chloroform and benzene
D. n-Butyl chloride and n-butyl bromide

Explanation

To determine which pairs of liquids show no net volume change and no heat effect upon mixing, we need to analyze each pair of liquids based on their properties and interactions. Here’s a step-by-step solution:

### Step 1: Understand the Criteria
We need to identify pairs of liquids that form ideal solutions. An ideal solution is characterized by:
- No net volume change upon mixing (ΔV = 0)
- No heat effect upon mixing (ΔH = 0)

### Step 2: Analyze Each Pair of Liquids

1. **Acetone and Ethanol**
- **Chemical Structures**: Acetone (CH₃COCH₃) and Ethanol (C₂H₅OH).
- **Interactions**: Acetone has an electronegative oxygen atom, and ethanol has an acidic hydrogen. They can form hydrogen bonds.
- **Conclusion**: This pair does not form an ideal solution because of the hydrogen bonding, leading to a non-ideal solution (ΔV ≠ 0, ΔH ≠ 0).

2. **Chlorobenzene and Bromobenzene**
- **Chemical Structures**: Chlorobenzene (C₆H₅Cl) and Bromobenzene (C₆H₅Br).
- **Interactions**: Both compounds share a common benzene ring and have similar molecular structures.
- **Conclusion**: They form an ideal solution (ΔV = 0, ΔH = 0) due to similar intermolecular forces.

3. **Chloroform and Benzene**
- **Chemical Structures**: Chloroform (CHCl₃) and Benzene (C₆H₆).
- **Interactions**: Chloroform and benzene do not have common structural components and behave differently.
- **Conclusion**: They do not form an ideal solution (ΔV ≠ 0, ΔH ≠ 0) due to different types of intermolecular interactions.

4. **Normal Butyl Chloride and Normal Butyl Bromide**
- **Chemical Structures**: Normal Butyl Chloride (C₄H₉Cl) and Normal Butyl Bromide (C₄H₉Br).
- **Interactions**: Both compounds share the common butyl group (C₄H₉).
- **Conclusion**: They form an ideal solution (ΔV = 0, ΔH = 0) due to similar molecular structures.

### Step 3: Final Conclusion
The pairs of liquids that are expected to show no net volume change and no heat effect upon mixing are:
- **Chlorobenzene and Bromobenzene** (Option B)
- **Normal Butyl Chloride and Normal Butyl Bromide** (Option D)

### Summary of Answers
- **Correct Options**: B and D