WAEC Chemistry 2022 Paper

Concept:The period and block of an element are decided by its highest occupied principal energy level and the subshell receiving the last electron.Explanation:The given configuration is $1s^2\,2s^2\,2p^6\,3s^2\,3p^6\,3d^{10}\,4s^2\,4p^4$.Total electrons $= 2 + 2 + 6 + 2 + 6 + 10 + 2 + 4 = 34$.The highest principal quantum number is $n = 4$, so the element lies in period 4.The last electron enters the $4p$ subshell, so the element belongs to the p-block.Thus, the element is in period 4, p-block.Answer:Option A — period 4, p-block.