a. Consider the following statement: “Although the entropy of a given system may increase, decrease, or remain constant, the entropy of the universe cannot decrease.” Is this statement true? Why?

b. Consider any two states, labeled 1 and 2. Show that if state 1 is accessible from state 2 by a real (irreversible) adiabatic process, then state 2 is inaccessible from state 1 by a real adiabatic process.