In the test of sulphate radical,the white precipitate of sulphate is soluble in

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:

Which of the following anions cannot be easily removed from its aqueous solution by precipitation?

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:

$A$ substance reacts with dilute $H_2SO_4$ to release a colorless gas which $(i)$ turns baryta water turbid and $(ii)$ turns acidic dichromate solution green. This reaction indicates the presence of which of the following?

To a solution of a colourless sodium salt,a solution of lead nitrate was added to form a white precipitate which dissolves in warm water and reprecipitates on cooling. Which of the following acid radicals is present in the salt?