Answer is: molar solubility of strontium carbonate is 2.32·10⁻⁵ M.
Chemical reaction: SrCO₃(s) → Sr²⁺(aq) + CO₃²⁻(aq).
Ksp = 5.4·10⁻¹⁰.
s(SrCO₃) = ?M.
s(SrCO₃) = s(Sr²⁺) =s(CO₃²⁻) = x.
Ksp = s(Sr²⁺) · s(CO₃²⁻).
Ksp = x · x.
5.4·10⁻¹⁰ = x².
x = √5.4·10⁻¹⁰ = 2.32·10⁻⁵ M.