Which pair from the following will not form an ideal solution?

Options

A. `C""Cl_4 +SiCl_4`
B. `H_2O+C_4H_9OH`
C. `C_2H_5Br +C_2H_5I`
D. `C_6H_(14)+C_7H_(16)`

Answer

To determine which pair of substances will not form an ideal solution, we need to analyze the molecular structures of the given pairs and see if they have similar skeletal structures. Ideal solutions are characterized by similar molecular structures, while non-ideal solutions exhibit significant differences in their molecular structures.

### Step-by-Step Solution:

1. **Understanding Raoult's Law**:
- Raoult's law states that the vapor pressure of an ideal solution is directly proportional to the mole fraction of the solvent. Ideal solutions obey this law completely.

2. **Identifying Ideal vs Non-Ideal Solutions**:
- Ideal solutions have similar molecular structures, while non-ideal solutions do not. Non-ideal solutions can show either positive or negative deviation from Raoult's law.

3. **Analyzing the Given Pairs**:
- **Pair 1: CCl4 and SiCl4**:
- Both have similar tetrahedral structures with a central atom difference (C vs Si). They are likely to form an ideal solution.
- **Pair 2: H2O and C4H9OH**:
- H2O (water) has a bent structure, while C4H9OH (butanol) has a more complex structure with a long hydrocarbon chain. The significant difference in structure suggests they will not form an ideal solution.
- **Pair 3: C2H5-Br and C2H5-I**:
- Both have the same ethyl group structure with only a difference in halogen (Br vs I). They are similar enough to form an ideal solution.
- **Pair 4: C6H14 and C7H16**:
- Hexane (C6H14) and Heptane (C7H16) are both alkanes with similar structures, differing only in the number of carbon atoms. They will also form an ideal solution.

4. **Conclusion**:
- The pair that will not form an ideal solution is **H2O and C4H9OH** (Option 2).

### Final Answer:
The pair that will not form an ideal solution is **H2O and C4H9OH**.