Calcium imide on hydrolysis gives gas (P) which on oxidation by bleaching powder gives gas (Q). Gas (Q)on reaction with magnesium gives compound (R) which on hydrolysis again gives gas (P). Identify (P) (Q), and (R)

• A

  ${\mathrm{N}}_2,{\mathrm{NH}}_3,\mathrm{MgNH}$

• B

  ${\mathrm{NH}}_3,{\mathrm{N}}_2,{\mathrm{Mg}}_3{\mathrm{N}}_2$

• C

  ${\mathrm{NH}}_3,{\mathrm{NO}}_2,\mathrm{Mg}{\left({\mathrm{NO}}_2\right)}_2$

• D

  ${\mathrm{N}}_2,{\mathrm{N}}_2{\mathrm{O}}_5,\mathrm{Mg}{\left({\mathrm{NO}}_3\right)}_2$