• # question_answer Which of the following electronic configuration is not possible according to Hund?s rule                  [Kerala PMT 2004] A)                 $1{{s}^{2}}2{{s}^{2}}$  B)                 $1{{s}^{2}}2{{s}^{1}}$ C)                 $1{{s}^{2}}2{{s}^{2}}2p_{x}^{1}2p_{y}^{1}2p_{x}^{1}$ D)                 $1{{s}^{2}}2{{s}^{2}}2p_{x}^{2}$ E)                 $1{{s}^{2}}2{{s}^{2}}2p_{x}^{2}2p_{y}^{1}2p_{z}^{1}$

According to Hund's rule electron first fill in unpaired form in vacant orbital then fill in paired form to stabilized the molecule by which $1{{s}^{2}},2{{s}^{2}},2p_{x}^{2}$ is not possible. According to Hund's rule. Because $2{{p}_{x}},{{p}_{y}},{{p}_{z}}$ have the same energy level so electron first fill in unpaired form not in paired form so it should be $1{{s}^{2}},\,2{{s}^{2}},\,2p_{x}^{1},2p_{y}^{1}$.