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 the evolution of a colourless gas (Y). X and Y, respectively, are:
1. \(X= CO_2,~Y=Cl_2 \)
2. \(X= Cl_2,~Y=CO_2 \)
3. \(X= Cl_2,~Y=H \)
4. \(X= H,~Y=Cl_2 \)