In the following reversible reaction$2{\text{SO}}_2\left(\text{g}\right)+{\text{O}}_2\left(\text{g}\right)\rightleftharpoons 2{\text{SO}}_3\left(\text{g}\right)+\text{Q cal}$ . Most suitable conditions for the formation of ${\text{SO}}_3$  is

$2{\text{SO}}_2\left(\text{g}\right)+{\text{O}}_2\left(\text{g}\right)\rightleftharpoons 2{\text{SO}}_3\left(\text{g}\right)+\text{Q cal}$

Formation of ${\text{SO}}_{\text{3}}$ favored at low temperature and high pressure.

The above reaction is an exothermic and the volume has been decreased in a forward direction.

Note: At high temperature dissociation of sulphur trioxide is taking place.