• # question_answer Which of the following electronic configurations is not possible [CPMT 2000] A)                 $1{{s}^{2}}\,\,2{{s}^{2}}$           B)                 $1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}$ C)                 $3{{d}^{10}}4{{s}^{2}}4{{p}^{2}}$           D)                 $1{{s}^{2}}2{{s}^{2}}\,2{{p}^{2}}3{{s}^{1}}$

When 2p orbital is completely filled then electron enter in the 3s. The capacity of 2p orbital containing ${{e}^{-}}$is 6. So $1{{s}^{2}},\,2{{s}^{2}}2{{p}^{2}}3{{s}^{1}}$ is a wrong electronic configuration the write is $1{{s}^{2}}2{{s}^{2}}2{{p}^{3}}.$