Answer : The value of
of the generic salt is, 
Explanation :
As we are given that, a solubility of salt is, 8.70 g/L that means 8.70 grams of salt present in 1 L of solution.
First we have to calculate the moles of salt 

Molar mass of
= 345 g/mol

Now we have to calculate the concentration of 
The equilibrium chemical reaction will be:

Concentration of
= 
Concentration of
= 
The solubility constant expression for this reaction is:
![K_{sp}=[A^{2+}][B^-]^2](https://tex.z-dn.net/?f=K_%7Bsp%7D%3D%5BA%5E%7B2%2B%7D%5D%5BB%5E-%5D%5E2)
Now put all the given values in this expression, we get:


Thus, the value of
of the generic salt is, 