The answer is sodium.
Radium, thorium, polonium, and uranium are all radioactive elements. Sodium is not radioactive.
Radium is a chemical element with the symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Its properties are similar to those of calcium, strontium, and barium. Radium is a highly radioactive element, and its decay products are responsible for the emission of radon gas.
Thorium is a chemical element with the symbol Th and atomic number 90. It is a silvery-white metal that is chemically similar to uranium. Thorium is found in nature, and it is also produced as a byproduct of uranium mining. Thorium is a relatively stable element, and it is not considered to be radioactive.
Polonium is a chemical element with the symbol Po and atomic number 84. It is a radioactive metal that is chemically similar to bismuth. Polonium is found in nature, and it is also produced as a byproduct of uranium mining. Polonium is a highly radioactive element, and its decay products are responsible for the emission of alpha particles.
Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-white metal that is chemically similar to thorium. Uranium is found in nature, and it is also produced as a byproduct of coal mining. Uranium is a radioactive element, and its decay products are responsible for the emission of alpha particles, beta particles, and gamma rays.
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white metal that is chemically very reactive. Sodium is found in nature, and it is also produced as a byproduct of salt mining. Sodium is not radioactive.