Influence of pressure, temperature, concentration and addition of inert gas on a reversible chemical reaction in equilibrium can be explained by formulating the expression for equilibrium constant `K_(c)` or `K_(p)` for the equilibrium. On the other hand Le Chatelier principle can be theoretically used to explain the effect of `P`, `T` or concentration on the physical or chemical equilibrium both.
For the reaction: `2SO_(2)+O_(2)hArr2SO_(3)`, `DeltaH=-ve`.
An increase in temperature shows:

Options

A. more dissociation of `SO_(3)` and a decrease in `K_(c)`
B. less dissociation of `SO_(3)` and an increase in `K_(c)`
C. more dissociation of `SO_(3)` and an increase in `K_(c)`
D. less dissociation of `SO_(3)` and a decrease in `K_(c)`

Explanation

An increase in temperture will favour backward reaction (endothermic). Also
`K_(c)` for `2SO_(2)+O_(2)hArrSO_(3)` will
`2.303 log"(K_(c_(2)))/(K_(c_(1)))=(DeltaH)/(R )[(T_(2)-T_(1))/(T_(1)T_(2))]`
`:' DeltaH=-ve`
`:. K_(c_(2)) lt K_(c_(1))`, if `T_(2) gt T_(1)`