Distinguish between hardness and alkalinity and explain how each influences scale and corrosion.

• A. Hardness is calcium and magnesium content; alkalinity is buffering capacity; hardness can cause scale; low alkalinity can cause corrosion.
• B. Hardness is buffering capacity; alkalinity is calcium/magnesium.
• C. Hardness affects pH only; alkalinity is total dissolved solids.
• D. Hardness and alkalinity are the same.

Answer: (A)