Multiple choice general knowledge science & technology Plutonium Pm Pr Pu Pt Reveal answer Fill a bubble to check yourself C Correct answer Explanation Plutonium is a radioactive element with atomic number 94, and its chemical symbol is 'Pu'. Promethium is 'Pm', Praseodymium is 'Pr', and Platinum is 'Pt'. Plutonium was named after the dwarf planet Pluto.