Isotopes can be constituted-of-or-filled-with francium.Logical formLearned from4 sentences. Isotopes can be constituted-of-or-filled-with silicon.Logical formLearned from4 sentences. Isotopes may pertain-to (chemical elements).Logical formLearned from4 sentences. An (isotope helium-3) can be rare.Logical formLearned from4 sentences. Isotopes can be constituted-of-or-filled-with zirconium.Logical formLearned from4 sentences. Radioactive isotopes may undergo concentration.Logical formLearned from4 sentences. A source can be constituted-of-or-filled-with isotopes.Logical formLearned from4 sentences. Isotopes can be constituted-of-or-filled-with radium.Logical formLearned from4 sentences. Some isotopes of radium can be radioactive.Logical formLearned from4 sentences. Radioactive isotopes can be known.Logical formLearned from4 sentences. An isotope may have a half-life of some days.Logical formLearned from4 sentences. Isotopes may pertain-to hydrogen.Logical formLearned from4 sentences. Isotopes can be constituted-of-or-filled-with einsteinium.Logical formLearned from4 sentences. Isotopes can be constituted-of-or-filled-with niobium.Logical formLearned from4 sentences. Isotopes may undergo (decay rates).Logical formLearned from4 sentences.