Answer
(a) 118; (b) 119
Work Step by Step
(a) The noble gas following radon (Rn) would be the next element in the group 18 of the periodic table. Since the seventh period of the periodic table has 32 members, and Rn has an atomic number of 86, the next noble gas would have an atomic number of 87. Therefore, the noble gas following radon (Rn) would be element number 86+32=118, which is known as oganesson (Og).
(b) The alkali metal following francium (Fr) would be the next element in group 1 of the periodic table. Since the seventh period of the periodic table has 32 members and Fr has an atomic number of 87, the next alkali metal would have an atomic number of 87+32=119.
