When $Cl_2$ water is added to a salt solution containing chloroform,the chloroform layer turns violet. The salt contains:

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

Assertion $(A) :- Fe^{+3}$ is not used in the brown ring test for $NO_3^{-}$.
Reason $(R) :-$ Reduction of $NO_3^{-}$ takes place during the test.

In the qualitative analysis of nitrate,a brown ring is formed due to the formation of:

When $Y$ is treated with $KMnO_4$,then the final precipitate is of:
$'X' \xrightarrow[BaCl_{2} \text{ solution}]{} 'Y' \quad (\text{White ppt., insoluble in dil. } HCl)$
$'X' \xrightarrow[\text{Flame test}]{} \text{Golden yellow flame}$

Which anion of a sodium salt gives a white precipitate upon heating with a magnesium salt?