Use the periodic table inside the front cover of this book to find the symbol or name for each of the following elements.
$\begin{array}{ll}{\text { Symbol}} & {\text { Name } } \\ {\text { Co }} & {\text { _______}} \\ {\text { ______ }} & {\text { rubidium }}\\ {\text { Rn }} & {\text { ______ }} \\ {\text { ______ }} & {\text { radium }}\\{\text {U}} & {\text { ______ }} \end{array}$