Question 393Steam Plants - Assistant Engineer

The correct answer is C) alkalinity. Phenolphthalein is used as an indicator to test boiler water for alkalinity. Alkalinity is a measure of the water's ability to neutralize acids, which is an important parameter in boiler water treatment to maintain the proper pH and prevent corrosion. Phenolphthalein changes color in the presence of alkaline substances, making it a suitable indicator for testing boiler water alkalinity. The other options are incorrect because hardness (A) is measured using other indicators, chloride content (B) is not typically tested with phenolphthalein, and hydrazine (D) is a chemical used in boiler water treatment, not a parameter tested with phenolphthalein.