If air at 20°C and 750 mm Hg pressure has a relative humidity of 80%, what is the actual percentage humidity? Given that the vapor pressure of water at 20°C is 17.5 mm Hg.

CHEMICAL ENGINEERING MCQs for PPSC, FPSC, NTS, and Pakistan government job tests. Select an option below, then read the explanation.

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Subject
CHEMICAL ENGINEERINGchemical-engineering
Published
12 Mar 2019
Last updated
28 May 2026

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Explanation

To find the percentage humidity, multiply the relative humidity (80%) by the ratio of water vapor pressure (17.5 mm Hg) to total pressure (750 mm Hg). This calculation results in approximately 79.62%, which corresponds to option C.

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