Vapour pressure of a saturated solution of a sparingly soluble salt `A_(2)B_(3)` is 31.8 mm of Hg at `40^(@)C`. If vapour pressure of pure water is 31.9 mm of Hg at `40^(@)C`, calculate the solubility product of `A_(2)B_(3)` at `40^(@)C`.

Explanation

To solve the problem of finding the solubility product (Ksp) of the sparingly soluble salt \( A_2B_3 \) at \( 40^\circ C \), we can follow these steps:

### Step 1: Understand the given data
- The vapor pressure of the saturated solution of \( A_2B_3 \) is \( P_s = 31.8 \, \text{mm of Hg} \).
- The vapor pressure of pure water is \( P_0 = 31.9 \, \text{mm of Hg} \).

### Step 2: Calculate the relative lowering of vapor pressure
The formula for relative lowering of vapor pressure is given by:
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