K and L shell of an element are completely filled and there are 16 electrons in M-shell and 2-electr — Atomic Structure Chemistry Question

💡 Solution & Explanation

K shell ($n=1$) has 2 electrons. L shell ($n=2$) has 8 electrons. M shell ($n=3$) has 16 electrons ($3s^2, 3p^6, 3d^8$). N shell ($n=4$) has 2 electrons ($4s^2$). Total electrons = $2 + 8 + 16 + 2 = 28$. The atomic number is 28. Therefore, correct answer is B.