The key step in the manufacturing of `H_(2)SO_(4)` by contact process is

Options

A. absorption of ` SO_(3)` in `H_(2)SO_(4)` to give oleum
B. dilution of oleum with water
C. burning of sulphur in air to generate `SO_(2)`
D. catalytic oxidation of `SO-(2)` with `O_(2)` to give `SO_(3)`

Explanation

The catalytic oxidation of `SO_(2)` with `O_(2)` to gives `SO_(3)` is the key step in the manufacturing of sulpuric acid by contact process.
`2SO_(2)(g)+O_(2)(g)underset(hArr)(v_(2)O_(5))2SO_(3)(g),`
`Delta_(1)H^(@)=-196"kj mol"^(-1)`