KEAM 2019 Physics and Chemistry Paper

An orange solid, i.e. (NH4)2Cr2O7(A) on heating gives a green residue, i.e. Cr2O3(B),a colourless gas, i.e. N2(C) and water vapours. The dry gas (N2) upon passing over heated Mg gave a white solid, i.e. Mg3N2(D) which upon subsequent reaction with water gave a gas, i.e. NH3(E) that gave dense white fumes with HCl.
Reactions involved are