In an adiabatic process, no energy is transferred as heat. Indicate whether each of the following statements about an adiabatic process in a closed system is always true, always false, or true in certain conditions (specify the conditions):

(a) ΔU = 0;

(b) q = 0;

(c) q , 0;

(d) ΔU = q;

(e) ΔU = w.