iiiIncrease in temperature shift the equilibrium backward to the left because the reaction is exothermicH  197kJ  SulphurVIoxide formed decomposes back to SulphurIVoxide and Oxygen to remove excess heat therefore a less yield of SulphurVIoxide is attained Very low temperature decrease the collision frequency of SulphurIVoxide and Oxygen and thus the rate of reaction too slow and uneconomical