• # question_answer General configuration of outermost and penultimate shell is $(n-1)\,{{s}^{2}}\,(n-1)\,\,{{p}^{6}}(n-1)\,\,{{d}^{x}}n{{s}^{2}}.$ If n = 4 and x = 5 then no. of proton in the nucleus will be   [MP PET 2003] A) > 25 B) < 24 C) 25 D) 30

Given n = 4 x = 5 So $\underset{3{{s}^{2}}}{\mathop{(4-1){{s}^{2}}}}\,\underset{3{{p}^{6}}}{\mathop{(4-1){{p}^{6}}}}\,\underset{3{{d}^{5}}}{\mathop{(4-1){{d}^{5}}}}\,\underset{4{{s}^{2}}}{\mathop{4{{s}^{2}}}}\,$ Total electron = 2 + 6 + 5 + 2 = 15 Electron in 1 + 2 orbit = 2 + 8 = 10 Total electron = 10 + 15 = 25 No. of electron = No. of proton So total proton = 25