Which of the species kclo2, nh4br, hno2, pbs is/are insoluble in water? 1. nh4br and nh3 2. kclo3 3. hno2 4. all of these 5. pbs?

PbS are not soluble in water.

Solubility rule:   "Like dissolve like"

Reason of insolubility of PbS.

When sulphides are attached with group one and group two elements of periodic table, they are soluble but when they are attached with transition metals like Pb, there is highly covalent bond which makes difficult dissociation of bonds in water.KClO2 and NH4Br are inoic substances , so they are easily soluble. HNO2 is weak acid which can ionize in water.