Which compounds with CrO4 2- and C2O2 2- ions are soluble in water, and which ones are insoluble?

Question

I can't find them in solubility table.

Answer 1

As long as they are polar, they are soluble in water (which is polar as well). If they are nonpolar, then they are not as soluble in water, and often create a visible layer. Off the top of my head, I know that K2CrO4 is soluble, along with the dichromate version (K3Cr2O7).
Oxalate (C2O2) is soluble as oxalic acid, H2C2O2.