Write the conditions to maximise the yield of `H_2SO_4` by contact process.

Explanation

Manufacture of sulphuric acid by Contact process involves three steps.
1. Burning of ores to form `SO_(2)`.
2. Conversion of `SO_(2)` to `SO_(3)` by the reaction of the former with `O_(2)` (`V_(2)O_(5)` is used in this process as a catalyst.)
3. Absorption of `SO_(3)` in `H_(2)SO_(4)` to give oleum (`H_(2)S_(2)O_(7)`)
The key step in this process is the second step. In this step, two moles of gaseous reactants combine to give one mole of gaseous product. Also, this reaction is exothermic. Thus, in accordance with Le Chatelier’s principle, to obtain the maximum amount of`SO_(3)` gas, temperature should be low and pressure should be high.