In the following reaction sequence, metal (A)+N2Δ⟶(B)−H2O⟶(C)+(D) white ppt (C) is formed and gas (D) is evolved. White ppt (C) dissolves in NaOH solution, while gas (D) gives white fumes in HCl Metal A is
Identify A, B, C, D, E, R and R1 in the following: