a measure of the tendency of the molecules of a liquid to escape into the gas phase is the liquid's
The answer you are looking for is Vapor Pressure
Vapor pressure is the pressure of vapor in contact with it's liquid. Vapor is a substance suspended into the air like a gas from a liquid. This matches your question. Therefore, Vapor pressure is the correct answer from the given choices.
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C.) A measure of the tendency of the molecules of a liquid to escape into the gas phase is the liquid's "Vapor Pressure"
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