A gas X is passed through water to form a saturated solution. The aqueous solution on treatment with silver nitrate gives a white precipitate. The saturated aqueous solution also dissolves magnesium ribbon with evolution of a colourless gas Y. Identify X and Y.
A. `X=CO_(2),Y=Cl_(2)`
B. `X=Cl_(2),Y=CO_(2)`
C. `X=Cl_(2),Y=H_(2)`
D. `X=H_(2),Y=Cl_(2)`