3. Which two elements in the ground one s -electron at the outer level? state have 3) F 1) 0 2) (4) 5) S Answer (score: 1):

The correct answer is 1) O and 5) S.<br /><br />Explanation:<br />The question is asking about the elements in the ground state that have one electron at the outer level. In the periodic table, the elements with one electron at the outer level are the alkali metals, which are in Group 1 of the periodic table. Oxygen (O) and Sulfur (S) are not alkali metals, but they have one electron at the outer level in their ground state.