Which of the following reactions proceeds at low pressure?

Consider the given endothermic reaction at equilibrium,$PCl_{5(g)} \rightleftharpoons PCl_{3(g)} + Cl_{2(g)}$. $A$ graph is plotted between concentration and time as shown. Effect-$1$ and Effect-$2$ are due to respectively:

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?
$(a)$ $PCl_{5(g)} \rightleftharpoons PCl_{3(g)} + Cl_{2(g)}$
$(b)$ $CaO_{(s)} + CO_{2(g)} \rightleftharpoons CaCO_{3(s)}$
$(c)$ $3Fe_{(s)} + 4H_{2}O_{(g)} \rightleftharpoons Fe_{3}O_{4(s)} + 4H_{2(g)}$

$aA \rightleftharpoons mB + nC$,$\Delta H = + x \ kcal$. If $m + n < a$,then conditions favouring forward reaction will be

In what manner will an increase of pressure affect the following equilibrium equation?
$C_{(s)} + H_2O_{(g)} \rightleftharpoons CO_{(g)} + H_{2(g)}$

The reaction $SO_2 + Cl_2 \rightleftharpoons SO_2Cl_2$ is exothermic. If some $SO_2$ is added to the equilibrium mixture at constant volume,then ...........