Why do non metal ions change from being soluble in solution to insoluble at the surface of the cathode

What is the [oh-] in a solution with a poh of 3.90

There is an area in idaho named craters of the moon where most of the ground is covered with basalt, adark gray, igneous rock with no visibl crystals. what can you infer about the geographical history of the area?

Compared with the freezing-point depression of a 0.01 m c6h12o6 solution, the freezing-point depression of a 0.01 m nacl solution is