`NH_(3)+O_(2)overset("Pt")to(A)`
`(A)+O_(2)to (B)`(brown fumes)
`(B)+H_(2)o to ( C)`(nitrogen in lower oxidation state) `+(D)`(nitrogen in higher oxidation state)
`( C)` and `(D)` both are oxoacids of nitrogen.
`( C)+I^(-)to (E)` (violets vapours).
Identify `(A),(B),( C),(D)` and `(E)`

Explanation

`4NH_(3)+5O_(2)underset(Delta)overset("Pt")to4NO+6H_(2)O`
`NO+1//20_(2) toNO_(2)`(brown fumes)
`NO_(2)+H_(2)O to HNO_(2)+HNO_(3)`(both oxoacids)
`2HNO_(2)+2I^(-) + 2H^(+)toI_(2) ("violent vapours")+2NO+2H_(2)O`.
So `( A)=NO, (B)=NO_(2), (C )=HNO_(2), (D)=HNO_(3)` and `(E)=I_(2)`