Consider the following reactions. In which cases is product formation favoured by decreased temperature?
$(a) \ N_{2(g)} + O_{2(g)} \rightleftharpoons 2NO_{(g)}; \ \Delta H^o = 181 \ kJ$
$(b) \ 2CO_{2(g)} \rightleftharpoons 2CO_{(g)} + O_{2(g)}; \ \Delta H^o = 566 \ kJ$
$(c) \ H_{2(g)} + I_{2(g)} \rightleftharpoons 2HI_{(g)}; \ \Delta H^o = -9.4 \ kJ$
$(d) \ H_{2(g)} + F_{2(g)} \rightleftharpoons 2HF_{(g)}; \ \Delta H^o = -541 \ kJ$

• A
  $a, b$
• B
  $b$ only
• C
  $a, b, c$
• D
  $c, d$