In the following diagram bunsen flame the $\left(\mathrm{X}\right)$ represents.

Then A may have:

$\underset{(\mathrm{mixture} \mathrm{of} \mathrm{two} \mathrm{anions})}{\mathrm{A}}\underset{\mathrm{excess} \mathrm{of} {\mathrm{BaCl}}_2}{\overset{\mathrm{Cold}}{\to }}\mathrm{white} \mathrm{ppt}. \stackrel{\mathrm{filtered}}{\to }\left(\mathrm{filterate}\right)\stackrel{\mathrm{boil}}{\to }\mathrm{white} \mathrm{ppt}.\downarrow$

Anion of $\left(\mathrm{A}\right)$ could be:

The acidic aqueous solution of Ferrous ion forms a brown complex in the presence of ${\mathrm{NO}}_3^{-}$ by the following two steps :

${\left[\mathrm{Fe}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6\right]}^{2+}+{\mathrm{NO}}_3^{-}+{\mathrm{H}}^{+}⟶\dots \dots \dots \dots ..+{\left[\mathrm{Fe}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6\right]}^{3+}+{\mathrm{H}}_2\mathrm{O}$

${\left[\mathrm{Fe}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6\right]}^{2+}+\dots \dots \dots \dots \dots \dots \dots \dots .+{\mathrm{H}}_2\mathrm{O}$

Complete and balance the equations.