Roasting of sulphides gives the gas X as a by-product. This is a colourless gas with choking smell of burnt sulphur and causes great damage to respiratory organs as a result of acid rain. Its aqueous solution is acidic acts as a reducing agent and its acid has never insolated. The gas X is

Options

A. `CO_(2)`
B. `SO_(3)`
C. `H_(2)S`
D. `SO_(2)`

Answer

d

Explanation

`S^(2-) + O_(2) overset("Roasting")(to) SO_(2) + 2e^(Theta)`
i. Sulphides on reasting necver form `SO_(3)` since in is produced by reacting `SO_(2)` with `O_(2)` in prence of a catalyat `(Pt , or V_(2)O_(3))` and at optimum temperature `(720K)` and high presence `(2 bar)`

ii. `SO_(2)` and `SO_(2)` both are colourless gas but `SO_(2)` has a choking smell of `SO_(2),NO_(2)` and `SO_(2)` from atmosphare after oxidation and reaction with water are major contributor to acid rain
`2SO_(2(g)) + O_(2(g)) + 2H_(2)O_((1)) rarr 2H_(2)SO_(4(Aq))`
`2NO_(2(g)) +_O_(2(g)) + 2H_(2)O_((1)) rarr 2HNO_(3(aq))`
So `X` bo `SO_(2)` not `SO_(3)`
iii. Aqueous solution of both `SO_(2)` and `SO_(3)` are acidic `SO_(2)` acts as reducing agent (undergo) oxidation from `+4 to +6`oxidation sate) but `SO_(4)` does acts as readicing agent (i.e. it has maximum oxidation sate of `+6)`
So `X` can be `SO_(2)` bot `SO_(2)`
iv `SO_(2)` reacts with `H_(2)O` as given below and `H_(2)SO_(3)` is never isolated

Hence the anwer is (d), i.e. `SO_(2)`