The solubility of PbSO4 in 0.01M Na2SO4 solution is      (Ksp of PbSO4 is 1.25 × 10–9)

Solubility of PbSO4 get suppressed in 0.01 M Na2SO4 solution due to common-ion effect and the following equilibrium gets established.Ksp = (S') x (S' + 0.01)Ksp ≅ S' x 0.01 ⇒ 1.25 x 10-9 = S' x 10-2⇒ S' = 1.25 x 10-7