Ka dibna wuxuu ku jawaabay su'aasha ka dib luqadda la mid ah sida marinka: Passage: kiimikada Soviet DK Dobroserdov ahaa saynisyahankii ugu horeeyay ee ku andacoonaya in ay helay eka-caesium, ama francium. In 1925, wuxuu arkay shucaaca daciif ah ee muunad ah potassium, biraha kale alkali, iyo si qalad ah ku soo gabagabeeyay in eka-caesium la wasakheeyo muunad (radioactivity ka muunad ahaa ka dabiiciga ah ee potassium radioisotope, potassium-40).
Qaybta 87aad