Formation of a solution from two components can be considered as :
(i) pure solvent `rarr` separated solvent molecules, `/_\H_(1)`
(ii) Pure solute `rarr`separated molecules,`/_\H_(2)`
(iii) separated solvent and solute molecules`rarr`solution, `/_\H_(3)`
solution so formed will be ideal if :

Options

A. `/_\H_("soln")=/_\H_(1) + /_\H_(2) +/_\H_(3)`
B. `/_\H_("soln")=/_\H_(1) + /_\H_(2) -/_\H_(3)`
C. `/_\H_("soln")=/_\H_(1) -/_\H_(2) -/_\H_(3)`
D. `/_\H_("soln")=/_\H_(3) - /_\H_(1) -/_\H_(2)`

Answer

To solve the problem regarding the formation of a solution from two components and determine the conditions for an ideal solution, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding the Components**:
- We have two components: a solvent (A) and a solute (B).
- The process of forming a solution can be divided into three steps:
- (i) Converting pure solvent (A) into separated solvent molecules, which requires energy change denoted as ΔH1.
- (ii) Converting pure solute (B) into separated solute molecules, which requires energy change denoted as ΔH2.
- (iii) Mixing the separated solvent (A) and solute (B) molecules to form the solution, which has an energy change denoted as ΔH3.

2. **Energy Changes in Each Step**:
- The energy required to separate the solvent molecules (ΔH1) and the energy required to separate the solute molecules (ΔH2) are both endothermic processes (they absorb energy).
- The mixing of the separated solvent and solute molecules (ΔH3) can either be exothermic (releases energy) or endothermic (absorbs energy).

3. **Condition for Ideal Solutions**:
- For a solution to be considered ideal, the overall enthalpy change (ΔH_solution) during the formation of the solution should be zero.
- Mathematically, this can be expressed as:
\[ ΔH_{solution} = ΔH_1 + ΔH_2 + ΔH_3 = 0 \]
- Rearranging gives us:
\[ ΔH_3 = - (ΔH_1 + ΔH_2) \]
- This means that the energy released during the mixing (ΔH3) should exactly balance the energy absorbed during the separation of the solvent and solute.

4. **Conclusion**:
- Therefore, the formation of an ideal solution occurs when the total enthalpy change (ΔH_solution) is zero, which implies that the interactions between the solute and solvent molecules (A-B interactions) are similar to those of the pure components (A-A and B-B interactions).

### Final Answer:
The solution formed will be ideal if:
\[ ΔH_{solution} = ΔH_1 + ΔH_2 + ΔH_3 = 0 \]