The formation of $SO_3$ takes place according to the following reaction: $2SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g)$; $\Delta H = -45.2 \ kcal$. The formation of $SO_3$ is favoured by:

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

$Le-Chatelier$'s principle is not applicable to:

The value of $\Delta H$ for the reaction $X_{2(g)} + 4Y_{2(g)} \rightleftharpoons 2XY_{4(g)}$ is less than zero. Formation of $XY_{4(g)}$ will be favoured at

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

Explain the effect of concentration on equilibrium using the following experiment:
$Fe^{3+}_{(aq)} + SCN^{-}_{(aq)} \rightleftharpoons [Fe(SCN)]^{2+}_{(aq)}$
(Yellow) (Colourless) (Deep red)