Use the Gibbs phase rule to find the degrees of freedom for the following systems at equilibrium: a. Liquid water in equilibrium with water vapor. b. Liquid water in equilibrium with humid air. c. A mixture of liquid water and liquid octane (which is immiscible in water) both in equilibrium with their vapors. d. A mixture of water, nitrogen, ethanol, and benzene. e. CO2 at its triple point.