$A$ brown ring appears in the test for

On treating a compound with warm dil. $H_{2}SO_{4}$,gas $X$ is evolved which turns $K_{2}Cr_{2}O_{7}$ paper acidified with dil. $H_{2}SO_{4}$ to a green compound $Y$. $X$ and $Y$ respectively are

$A$ salt gives violet vapours when treated with concentrated $H_2SO_4$,it contains

The Chromyl chloride test is performed for the confirmation of the presence of which of the following in a mixture?

$A$ salt solution is treated with chloroform drops. Then it is shaken with chlorine water. The chloroform layer becomes violet. The solution contains:

Sodium salt solution $+ \, AgNO_3$ solution $\to$ Coloured precipitate: If the coloured precipitate is soluble in both dilute $HNO_3$ and excess concentrated $NH_3$ solution,then which of the following anions is present in the salt solution?