An element M reach with chlorine to form a compound X. The bond angle in X is  120° and X is trigonlar planar in shape. The atomic number of M is likely

BCI₃  is trigonal planar with bond angle 120° . M is Boron
Z = 35 is Bromine     ${\text{BrCl}}_{\text{3}}$is T – shaped
Z = 7 is Nitrogen.      ${\text{NCl}}_{\text{3}}$is pyramidal
Z = 15 is Phosphorous   
 ${\text{PCl}}_{\text{3}}$ is pyramidal