The formation of `SO_(3) ` from ` SO_(2) and O_(2) ` takes place in the following steps :
`(i) SO_(2)+2NO_(2) to 2SO_(3)+2NO`
`(ii) 2NO +O_(2) to 2NO_(2)`

Options

A. `NO_(2) ` is intermediate
B. `NO ` is catalyst
C. `NO_(2) ` is catayst and `NO ` is intermediate
D. `NO` is catalyst and `NO_(2) ` is intermediate

Answer

C

Explanation

The reactants first combine with the catalyst to form an intermediate complex which is short lived and decomposes to form the product and regenerating the catalyst hence NO is intermediate complex and `NO_(2)` is the catalyst .