Stability of nitrides of IIA group elements is in order

• A

  ${\mathrm{Ca}}_3{\mathrm{N}}_2<{\mathrm{Mg}}_3{\mathrm{N}}_2<{\mathrm{Be}}_3{\mathrm{N}}_2$

• B

  ${\mathrm{Be}}_3{\mathrm{N}}_2<{\mathrm{Mg}}_3{\mathrm{N}}_2<{\mathrm{Ca}}_3{\mathrm{N}}_2$

• C

  ${\mathrm{Ca}}_3{\mathrm{N}}_2<{\mathrm{Be}}_3{\mathrm{N}}_2<{\mathrm{Mg}}_3{\mathrm{N}}_2$

• D

  ${\mathrm{Mg}}_3{\mathrm{N}}_2<{\mathrm{Be}}_3{\mathrm{N}}_2<{\mathrm{Ca}}_3{\mathrm{N}}_2$