Which curve indicates whether water is corrosive, scaling or neutral?

• A. Baylis Curve
• B. pH Curve
• C. Larson Curve
• D. Resistance Curve

Answer: (C)

The idea being tested is how to determine whether water will be corrosive, cause scaling, or be neutral. This depends on whether the water is undersaturated, at saturation, or oversaturated with minerals like calcium carbonate. The curve that does this is designed to combine key water-chemistry factors (such as hardness, alkalinity, pH, and temperature) and show where the sample falls relative to the calcium carbonate solubility boundary. When the water sits below that boundary, it tends to be corrosive to metals; on the boundary, it’s neutral; and above the boundary, it tends to precipitate minerals as scale. The Larson curve is the tool used to visualize this three-way outcome, giving a quick, graphical way to assess corrosion risk versus scaling tendency for a given water chemistry.

Other curves aren’t used for this purpose: a Baylis curve and a pH curve don’t directly indicate the tendency toward corrosion or scale formation, and a resistance curve relates to electrical resistance rather than the chemical balance that drives corrosion or scaling.