In a specified system, water activity is defined as the ratio of _____
(a) Fugacity of water vapor to fugacity of pure water at the specified system temperature and 1 atmospheric pressure
(b) Fugacity of pure water at the specified system temperature and 1 atmospheric pressure to fugacity of water vapor
(c) Fugacity of pure water at the specified system temperature and 1 atmospheric pressure
(d) Fugacity of water vapor
The question was asked in my homework.
This intriguing question comes from Principles of Semi-Moist Foods-1 topic in section Principles of Semi-Moist Foods, Principles of Food Preservation by Fermentation, Principles of Food Pickling and Curing and Principles of Food Storage Stability of Food Engineering