Cd(IO3)2(s) <-- --> Cd++(aq) + 2 { IO3- => HIO3 }
___/________________S____________2S_________

2S = [IO3-]+[HIO3]
con Ka = [H+]*[IO3-]/[HIO3] => [HIO3] = [H+]*[IO3-]/Ka
=> ... [IO3-] = 2S*Ka/(Ka+[H+]) =
= 2S*1.7*10^-2 / (1.7*10^-2 + 10^-3.5) = 1.96*S

Kps = [Cd++]*[IO3-]^2 = S*(1.96*S)^2 = 3.86*S^3

=> S= (2.3*10^-8 / 3.86)^1/3 = 1.81*10^-3mol/L