$A$ chloride salt solution acidified with dil. $HNO_3$ gives a curdy white precipitate,$[A]$,on addition of $AgNO_3$. $[A]$ on treatment with $NH_4OH$ gives a clear solution,$B$. Identify $[A]$ and $B$.

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 anion's aqueous solution gives a white precipitate with $AgNO_3$,which is soluble in excess $NH_4OH$?

How do you account for the following observations?
$(a)$ Though alkaline potassium permanganate and acidic potassium permanganate both are used as oxidants,yet in the manufacture of benzoic acid from toluene,we use alcoholic potassium permanganate as an oxidant. Why? Write a balanced redox equation for the reaction.
$(b)$ When concentrated sulphuric acid is added to an inorganic mixture containing chloride,we get a colourless pungent-smelling gas $HCl$,but if the mixture contains bromide,then we get red vapours of bromine. Why?

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

Which of the following substances releases $SO_2$ gas upon reaction with dilute $H_2SO_4$?