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

White heavy precipitates are formed when $BaCl_2$ is added to a clear solution of compound $A$. Precipitates are insoluble in dilute $HCl$. Then,the compound $A$ is

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

$[X] + H_2SO_4 \rightarrow [Y]$ (a colorless gas with a pungent smell). $[Y] + K_2Cr_2O_7 + H_2SO_4 \rightarrow$ green solution. What are $[X]$ and $[Y]$?

$A$ salt is heated first with dil. $H_2SO_4$ and then with conc. $H_2SO_4$. No reaction takes place. It may be

$[X] +$ dil. $H_{2}SO_{4} \longrightarrow [Y]:$
Colourless,suffocating gas
$[Y] + K_{2}Cr_{2}O_{7} + H_{2}SO_{4} \longrightarrow$
Green colouration of solution
Then,$[X]$ and $[Y]$ are