- - Carbon-12 and carbon-14
- - Elemental forms used in carbon dating
- - Carbon 14 and strontium 90
- - Carbon 14 and uranium 235
- - Carbon 13 et al.
- - Carbon 14 and others
- - U 235 et al.
- - Deuterium and the like
- - soot pies turn out to be different forms of the same chemical element
- - I quit drugs to inhale oxygen, deuterium and tritium, perhaps
- - so p.o. site is affected by radioactive atoms
- - Springfield minor leaguers
- - One getting distress call about Kitty picking up energy produced by radioactive type of elements
- - U-235 and C-14
- - I call for help carrying most important electronic and nuclear materials
- - Uranium 235 and uranium 238, for two
- - U-235 and U-238
- - I like that poet's new elementary forms
- - Elemental variants
- - Uranium 238 and strontium 90
- - Poet is so freaked out with those with a chemical dependency
- - Deuterium and tritium
- - Elementary variants to posies after arrangement
- - Some are radioactive
- - Chemical variants
- - Springfield's minor-league team on "The Simpsons"
- - Chemist's relatives?
- - Atoms with the same number of protons
- - Uranium has many
- - They share the same atomic number
- - They may be radioactive
- - Deuterium and tritium, to hydrogen
- - Elemental relatives
- - Cobalt 60 and iodine 131, e.g.
- - Cobalt-60 and iodine-131
- - Uranium 235 and 238
- - Uranium 235 and uranium 238
- - Elemental variations
- - Elemental cousins
- - U-235 and U-238 e.g.
- - Protium and tritium, e.g.
- - Elements having the same atomic number.
- - Basis of most chemical elements.
- - Forms of elements having same atomic number.
- - Some atoms
- - Dating material
- - Varieties of the same element with differing numbers of neutrons
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