Ksp is the equilibrium constant of solubility of a solid in a solution.
The solid is CaC2O4.
The dissolved ions are Ca2+ and C2O4 2-
The equation of the equilibrium is
\(CaC_{2}O_{4} = Ca^{2+} + {C_{2}O_{4}}^{2-}\)
Then Ksp = [Ca 2+][C2O4 2-]
Where the [ ] indicates molar concentration
The chemical equation for this equilibrium implies [Ca 2+] = [C2O4 2-]. Name X this quantity
Ksp = x^2 ==> x = square root of Ksp
x = sqrt(2.3 10^ -9) = 4.8 10^ -5
Which is the second option.
