• # question_answer An atom has 2 electrons in $K$ shell, 8 electrons in $L$ shell and 6 electrons in $M$ shell. The number of $s$-electrons present in that element is            [CPMT 1989] A)                 6              B)                 5 C)                 7              D)                 10

Shell = K, L, M    = $1{{s}^{2}}$ $2{{s}^{2}}2{{p}^{6}}$ $3{{s}^{2}}3{{p}^{4}}$                 Hence the number of s electron is 6 in that element.