$[X] + H_2SO_4 \to [Y]$ (a colourless gas with irritating smell).
$[Y] + K_2Cr_2O_7 + H_2SO_4 \to$ green solution.
$[X]$ and $[Y]$ are:

$Na_2CO_3$ cannot be used to identify which of the following ions?

When $BaCl_2$ is added to a clear solution of a compound $(X)$,a heavy white precipitate is formed which does not dissolve in $dil. HCl$. What is the compound $(X)$?

Which reagent is used to remove $SO_4^{2-}$ and $Cl^{-}$ ions from a solution?

$A$ 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 $B$.

$H_2S$ gas is not evolved when $SO_3^{2-}$ ion reacts with the following reagents.