Find number of species which produce elemental sulphur when treated with `H_(2)S,`
`Fe^(3+),Fe^(2+), SO_(2), H_(2)O, O_(3), HNO_(3)`

Answer

5

Explanation

`Fe^(3+)+H_(2)toS+Fe^(2+)`
`SO_(2)+2H_(2)Sto3S+2H_(2)O`
`H_(2)O_(2)+H_(2)Sto2H_(2)O+S`
`H_(2)S+O_(3)toH_(2)O+S+O_(2)`
`2HNO_(3)+H_(2)Sto2NO_(2)+S+2H_(2)O`