When a mixture of `K_(2)Cr_(2)O_(7)` and `NH_(4)Cl` is heated , a colourless gas in evloved which is neither combustiible nor a supporter of combusion . However , Mg continued to burn in it. When the gas (A) is reacted with calcium carbide in it . When the gas (A) is reacted with calcium carbide in electric furnace , a solid (B) is obtained . (B) undergoes slow hydrolysis forming an insoluble compound (C) and the solution of the compound (D). (D) truns Nessle's reagent brown. Identify (A) to (D) . Write the reactions involved.

Explanation

A : `N_(2)` B : `CaCN_(2)` C: `CaCO_(3)` D : `NH_(2)`