The solubility product to different sparingly soluble salts are1) XY = 4 × 10–202) X2Y = 3.2 × 10–113) XY3 = 2.7 × 10–31The increasing order of solubility is

1) XY(s)⇌XY(aq)→X+ S1+Y-S1 Ksp = S1 x S1 ⇒ S1 = 2×10-10 2) X2Y(s)⇌XYS2(aq)→2X+2S2aq+Y-2S2aqKsp = (2S2)2 x S2 ⇒  3.2 x 10-11 = 4S23                                     ⇒  S2 = 2 x 10-4 3) XY3(s)⇌XY3(aS3q)→X+3S3aq+3Y-3S3aq Ksp = (S3)2 x (3S3) ⇒  2.7 x 10-31 = 27S34                                     ⇒  S3 = 10-8