question_answer 66)

  Amongst the following elements whose electronic configurations are given below, the one having the highest ionisation enthalpy is     (a) \[[Ne]3{{s}^{2}}3{{p}^{1}}\]                 (b) \[[Ne]3{{s}^{2}}3{{p}^{3}}\]                 (c) \[[Ne]3{{s}^{2}}3{{p}^{2}}\]                        (d) \[[Ar]3{{d}^{10}}4{{s}^{2}}4{{p}^{3}}\]

Answer:

  (b) The element is phosphorus. It has stable configuration as outermost p-orbitals are half filled. The element (d)also belongs to group 15, but its ionisation enthalpy is less than phosphorus as its atomic radius is higher than phosphorus. The element (a) is alkali metal and element (c) is a member of group 14 i.e., silicon.