Multiple choice Which of the following elements belong to 5th period of the periodic table? Ba Rb I Po Ag Au 1, 2 and 3 1, 3 and 6 2, 3 and 5 3, 4 and 5 4, 5 and 6 Reveal answer Fill a bubble to check yourself C Correct answer Explanation Rubidium (37Rb: [Kr] 5S1) belongs to 5th period of the periodic table. Iodine (53I: [Kr] 4d10 5s2 5p5) belongs to 5th period of the periodic table. Silver (47Ag: [Kr] 4d10 5s1) belongs to 5th period of the periodic table.