To determine which quantities increase with dilution at a given temperature, we need to analyze the behavior of different properties when a solution is diluted. Let's break down the solution step by step.
### Step-by-Step Solution
1. **Understanding Dilution**:
- When a solution is diluted, the volume of the solution increases. This results in a decrease in the concentration of solutes (number of moles per unit volume).
**Hint**: Remember that dilution means increasing the volume of the solution, which affects the concentration of solutes.
2. **Degree of Dissociation**:
- The degree of dissociation of an electrolyte increases with dilution. This is because as the concentration of the solution decreases, the ions produced from the dissociation have more space to exist without recombining.
**Hint**: Consider how the presence of more solvent allows ions to remain separated, leading to a higher degree of dissociation.
3. **Analyzing the Options**:
- For the options given:
- **C**: Degree of dissociation of 10^-3 acetic acid will increase with dilution.
- **D**: Degree of dissociation of 10^-3 molar aniline solution will also increase with dilution.
- Both C and D are correct.
**Hint**: Focus on how dilution affects the ability of molecules to dissociate into ions.
4. **pH Calculation**:
- pH is defined as the negative logarithm of the hydrogen ion concentration (pH = -log[H+]). When the solution is diluted, the concentration of H+ ions decreases, leading to an increase in pH.
**Hint**: Remember that a decrease in concentration of H+ ions means the solution becomes less acidic, which increases pH.
5. **Analyzing pOH**:
- For aniline, which is a weak base, when diluted, the concentration of OH- ions decreases. Since pOH is the negative logarithm of the hydroxide ion concentration (pOH = -log[OH-]), a decrease in [OH-] leads to an increase in pOH.
- However, since pH + pOH = pKw (which is constant at a given temperature), if pOH increases, then pH must decrease.
**Hint**: Keep in mind the relationship between pH and pOH, and how they are inversely related due to the constant pKw.
6. **Conclusion**:
- The quantities that increase with dilution at a given temperature are:
- Degree of dissociation of acetic acid (C)
- Degree of dissociation of aniline (D)
- pH of acetic acid solution (A)
- The pH of aniline solution decreases, so it is not included in the correct answers.
### Final Answer:
The correct options that increase with dilution at a given temperature are A, C, and D.
