When a mixture of ammonium chloride and potassium dichromate was heated, a stable colourless gass (A) was evolved which did not support combustion, but magnesium continued to burn in it. The gas (A) reacted with calcium carbide in an electric furnace a solid (B) which was slowly hydrolysed by water forming an insoluble substance (C) and the solution of a substance (D) which turned Nessler's reagent brown. Identify substances (A) to (E) and explain all the reactions involved.

When a mixture of ammonium chloride and potassium dichromate was heate

1.	When a mixture of ammonium chloride and potassium dichromate was heated, a stable colourless gass (A) was evolved which did not support combustion, but magnesium continued to burn in it. The gas (A) reacted with calcium carbide in an electric furnace a solid (B) which was slowly hydrolysed by water forming an insoluble substance (C) and the solution of a substance (D) which turned Nessler's reagent brown. Identify substances (A) to (E) and explain all the reactions involved.
Answer» Solution :(i) `2NH_(4)Cl+K_(2)Cr_(2)O_(7)tounderset("Amm.dichromate")((NH_(4))_(2)Cr_(2)O_(7)+2KCl)` (ii) `(NH_(4))_(2)Cr_(2)O_(7)overset("Heat")tounderset((A))(N_(2))+Cr_(2)O_(3)+4H_(2)O` (iii) `3Mg+N_(2)overset(Delta)tounderset("Magnesium nitride")(Mg_(3)N_(2)` (iv) `underset("Calcium carbide")(CaC_(2))+N_(2)overset("Heat")tounderset("Cal.cyanamide (B)")(CaCN_(2))+C` (v) `underset((B))(CaCN_(2))+3H_(2)Otounderset("Cal.carbonate (C)")(CaCO_(3))+underset("Ammonia (D)")(2NH_(3))` (VI) For reaction with NESSLER's reagent,