Hard water, which contains mg2+ and ca2+ ions, tends to form a ring in a bathtub due to its reaction with the soluble anions in soap. The formation of this insoluble material is an example of.

All of the following items are important to know when diagnosing an engine driveability problem except for thea. type of gasoline usedb. brand of engine oil usedc. temperature of the engine when the problem occursd. list of previous repairs