Calcium imide on hydrolysis gives gas $(B)$ which on oxidation by bleaching powder gives gas $(C)$. Gas $(C)$ on reaction with magnesium gives compound $(D)$ which on hydrolysis gives again gas $(B)$. Identify $(B)$,$(C)$ and $(D)$.

• A
  $NH_3, N_2, Mg_3N_2$
• B
  $N_2, NH_3, MgNH$
• C
  $N_2, N_2O_5, Mg(NO_3)_2$
• D
  $NH_3, NO_2, Mg(NO_2)_2$