• # question_answer 7) An element 'M' has an atomic number 9 and its atomic mass 19. The ion of M will be represented by A)  M                   B)  ${{M}^{2+}}$C)  ${{M}^{-}}$                  D)         ${{M}^{2-}}$

The electronic configuration of M is 2, 7. It needs one electron to complete its octet. It has a strong tendency to gain 1 electron and so its ion will be.  ${{M}^{-}}$.