Which of the following statements are correct?
(a) S___S bond is present in `H_(2)S_(2)O_(6)`
(b) In peroxosulphuric acid `(H_(2)SO_(5))` sulphur is in + 6 oxidation steta
(c )` Iron powder along with `Al_(2)O_(3) and K_(2)O` is used as a catalyst in the preparation of `NH_(3)` by Haber's process
(d) Change in enthalpy is positive for the preparation of `SO_(3)` by catalytic oxidation of `SO_(2)`

Answer

A, B

Explanation

Structure of `H_(2)S_(2)O_(6)` is as shown below

It contains one S__S bond.
(b) In peroxosulphuric acid `(H_(2)SO_(5))` sulphur is in + 6 oxidation state. Structure of `H_(2)SO_(5)` is

Let oxidation state of s`=x`
`2xx(+1)+x+3xx2xx(-1)=0`
`x-6=0`
`x=6`
(c ) During preparation of ammonia , iron oxide with small amount of `K_(2)OandAl_(2)O_(3)` is used as a catalyst to increase the rate of attainment of equilibrium.
(d) Change in enthalpy is negative for preparation of `SO_(3)` by catalytic oxidation of `SO_(2)`.