Consider the following reactions. In which cases is the product formation favoured by decreased pressure?
(1) $\mathrm{CO}_{2}(g)+\mathrm{C}(s) \rightleftharpoons 2 \mathrm{CO}(g) ; \quad \Delta H^{\circ}=+172.5 \mathrm{~kJ}$
(2) $\mathrm{N}_{2}(g)+3 \mathrm{H}_{2}(g) \rightleftharpoons 2 \mathrm{NH}_{3}(g) ; \quad \Delta H^{\circ}=-91.8 \mathrm{~kJ}$
(3) $\mathrm{N}_{2}(g)+\mathrm{O}_{2}(g) \rightleftharpoons 2 \mathrm{NO}(g) ; \quad \Delta H^{\circ}=181 \mathrm{~kJ}$
(4) $2 \mathrm{H}_{2} \mathrm{O}(g) \rightleftharpoons 2 \mathrm{H}_{2}(g)+\mathrm{O}_{2}(g) ; \quad \Delta H^{\circ}=484.6 \mathrm{~kJ}$
(a) 2,3
(b) 3,4
(c) 2,4
(d) 1,4