Does the number of moles of reaction products increase, decrease or remain the same when each of the following equilibria is subjected to a decrease in pressure by increasing the volume? (a) PCl 5 (g) ⇌ PCl 3 (g) + Cl 2 (g) (b) CaO (s) + CO 2 (g) ⇌ CaCO 3 (s) (c) 3Fe (s) + 4H 2 O (g) ⇌ Fe 3 O 4 (s) + 4H 2 (g)