What is the color of the precipitate formed when phosphate ions react with ammonium molybdate?

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

Which of the statement is incorrect for the given paragraph?
Simple salt $\xrightarrow{\text{Flame test}}$ Golden yellow flame
Simple salt $\xrightarrow[MnO_2]{Conc. H_2SO_4} (X)$ Yellowish green gas
Simple salt $\xrightarrow{AgNO_3} (Z)$ White ppt. (Insoluble in dil. $HNO_3$)
Simple salt $\xrightarrow[Conc. H_2SO_4]{K_2Cr_2O_7} (Y)$ Reddish brown vapour

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

$X$ (salt) + $AgNO_3$ $(aq.) \to \underset{(\text{Yellow ppt.})}{Y \downarrow}$ (soluble in excess of $NH_3$ solution). Salt $X$ does not contain:

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