`[X]+H_(2)SO_(4)to[Y]` a colourless gas with irritating smell,
` [Y]+K_(2)Cr_(2)O_(7)+H_(2)SO_(4)to` green solution.[x] and [Y] are

Options

A. `SO_(3)^(2-)`,`SO_(2)`
B. `Ci^(-)`,HCl
C. `S^(-)`,`H_(2)S`
D. `CO_(3)^(2-)`,`CO_(2)`

Explanation

`SO_(2)` and `H_(2)S` both being reducing agents, can turn acidified dichromate solution green. `SO_(2)` can be obtained by the action of acid upon sulphite while `H_(2)S` is evolved by the action of acid upon sulphide. However, `SO_(2)` has a burning sulphur smell which is irritating. `H_(2)S` has rotten egg like smell.
Hence, (A) is the correct answer.