$A$ mixture when heated with conc. $H_2SO_4$ and $MnO_2$ produces brown fumes due to the presence of:

Select the correct match for the separation of anions using the given reagent.

Given below are two statements:
Statement $I$: Griess-Ilosvay test is used for the detection of nitrite ion, which involves the use of sulphanilic acid and $\alpha$-naphthylamine reagent.
Statement $II$: In the above test, sulphanilic acid is diazotized by the acidified nitrite ion, which on further coupling with $\alpha$-naphthylamine forms an azo-dye.
In the light of the above statements, choose the correct answer from the options given below.

$A$ 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 will not produce a precipitate with $AgNO_3$ solution?

Which of the following is correctly matched?