Which of the following reagents would you use to separate $SO_4^{2-}$ ions from a solution containing a mixture of $SO_4^{2-}$ and $Cl^-$ ions?

During the detection of an acidic radical present in a salt,a student obtains a pale yellow precipitate that is soluble with difficulty in $NH_4OH$ solution when the sodium carbonate extract is first acidified with dil. $HNO_3$ and then $AgNO_3$ solution is added. This indicates the presence of:

$M \text{ (Salt)} + \text{Dil. } HCl \xrightarrow{\text{Warm}} N \uparrow + P \downarrow$. Gas $N$ changes the colour of $FeSO_4$ solution into a yellow solution. Then,salt $M$ in the above reaction is:

An anion solution gives a white precipitate with $AgNO_3$ solution. The precipitate dissolves in dilute ammonia due to the formation of:

In a test tube containing a salt, a few drops of dilute $\text{H}_2\text{SO}_4$ were added, which gave colourless vapours having the smell of vinegar. The vapours turned the blue litmus paper red. Identify the correct anion from the following:

Which of the following silver precipitates dissolves in $dil. \, HNO_3$ to produce a clear solution?