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 $(X)$?

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

Which of the following ions produces violet vapors upon reaction with concentrated $H_2SO_4$?

$A$ white sodium salt dissolves readily in water to give a solution which is neutral to litmus. When silver nitrate solution is added to the aforementioned solution,a white precipitate is obtained which does not dissolve in dilute nitric acid. The anion is:

On addition of conc. $H_2SO_4$ to a chloride salt,colourless fumes are evolved,but in the case of an iodide salt,violet fumes are observed. This is because:

$A$ salt gives violet vapours when treated with conc. $H_2SO_4$. It contains