Question

For an exothermic dissolution process, increase in temperature will result in:

• A. increase in solubility
• B. decrease in solubility
• C. no change in solubility
• D. cannot be predicted

Answer 1

The correct option is B decrease in solubility

Dissolution is a process where a solute in gaseous, liquid or solid phase dissolves in a solvent to form a solution. ​
It involves ​three steps:
Step 1: Involves the separation of solvent molecules ($\Delta H_1$)
Step 2: Separation of solute molecules ($\Delta H_2$)
Step 3: Mixing of solute and solvent molecules ($\Delta H_3$)
The heat of solution​,
$\Delta H_{solution}=\Delta H_1$ + $\Delta H_2$ + $\Delta H_3$​

Effect of temperature on solubility will be based on the nature of dissolution.
If dissolution is an exothermic process, heat will be release when the solute and solvent get dissolved. When we increase the temperature it will result in decrease in solubility of the solute in solvent. This is based on the Le-Chatelier's principle.