question_answer

                With which of the following electronic configuration an atom has the lowest ionisation enthalpy?

A)                                                                                                                                                                                            \[1{{s}^{2}}\,2{{s}^{2}}\,2{{p}^{5}}\]      

B)                 \[1{{s}^{2\,}}\,2{{s}^{2}}\,2{{p}^{3}}\]

C)                 \[1{{s}^{2}}\,2{{s}^{2}}\,2{{p}^{5}}\,3{{s}^{1}}\]

D)                 \[1{{s}^{2}}\,2{{s}^{2}}\,2{{p}^{6}}\]

Correct Answer: C

Solution :

                The electronic configuration  shows lowest ionisation energy because this configuration is unstable due to the presence of one electron in s-orbital. Hence, less energy is required to remove the electron.