when the salt AgI dissolves in water it dissociates as follows; AgI ---> Ag⁺ + I⁻ molar solubility is the number of moles that are dissolved in 1 L of solution. If molar solubility of AgI is x, then molar solubility of Ag⁺ is x and I⁻ is x. the formula for solubility product constant - ksp of AgI is given below ksp = [Ag⁺][I⁻] ksp = (x)(x) ksp = 8.51 x 10⁻¹⁷ therefore, x² = 8.51 x 10⁻¹⁷ x = 9.22 x 10⁻⁹ since molar solubility of AgI is x, then molar solubility of AgI is 9.22 x 10⁻⁹ M
