Select the correct statement(s).

In group Ill, ${\mathrm{Fe}}^{3+}$ and ${\mathrm{Cr}}^{3+}$ can be differentiated by increasing ${\mathrm{NH}}_4^{+}$ ion concentration.

In Vth group, ${\mathrm{Na}}_2{\mathrm{CO}}_3$ is added to precipitate out only the carbonates of ${\mathrm{Ba}}^{2+},{ \mathrm{Sr}}^{2+}$and ${\mathrm{Ca}}^{2+}$  

Like brown ring · test, diphenylamine test is given only by salts containing ${\mathrm{NO}}_3^{-}$.

Sodium chloride on heating with .aqueous solution of ${\mathrm{K}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7$ and concentrated ${\mathrm{H}}_2{\mathrm{SO}}_4$ produces deep red vapours.