A students takes 4 mL of distilled water in each of four test tubes I, II, III and IV, and then dissolves an equal amounts of four differents salts namely `NaC1` in `I` , `CaC1_(2)` in `II` , `MgC1_(2)` in `III` and `KC1` in `IV`. He then adds 8 drops of the given soap solution to each teat tube and shakes the contents of the test tube 10 times. In which test tubes will enough lather (foam) be formed?