Context and question: There are 29 isotopes of copper. 63Cu and 65Cu are stable, with 63Cu comprising approximately 69% of naturally occurring copper; they both have a spin of 32. The other isotopes are radioactive, with the most stable being 67Cu with a half-life of 61.83 hours. Seven metastable isotopes have been characterized, with 68mCu the longest-lived with a half-life of 3.8 minutes. Isotopes with a mass number above 64 decay by , whereas those with a mass number below 64 decay by +. 64Cu, which has a half-life of 12.7 hours, decays both ways.
What is the half life of the copper isotope 67Cu?
Answer: 61.83 hours
Context and question: In the Western Balkans, South Slavs and Germanic Gepids intermarried with Avar invaders, eventually producing a Slavicized population.[citation needed] In Central Europe, the Slavs intermixed with Germanic and Celtic, while the eastern Slavs encountered Uralic and Scandinavian peoples. Scandinavians (Varangians) and Finnic peoples were involved in the early formation of the Rus' state but were completely Slavicized after a century. Some Finno-Ugric tribes in the north were also absorbed into the expanding Rus population. At the time of the Magyar migration, the present-day Hungary was inhabited by Slavs, numbering about 200,000, and by Romano-Dacians who were either assimilated or enslaved by the Magyars. In the 11th and 12th centuries, constant incursions by nomadic Turkic tribes, such as the Kipchaks and the Pechenegs, caused a massive migration of East Slavic populations to the safer, heavily forested regions of the north. In the Middle Ages, groups of Saxon ore miners settled in medieval Bosnia, Serbia and Bulgaria where they were Slavicized.
What is another name for the Finnic peoples?
Answer: unanswerable
Context and question: The botanical term "Angiosperm", from the Ancient Greek , angeion (bottle, vessel) and , (seed), was coined in the form Angiospermae by Paul Hermann in 1690, as the name of one of his primary divisions of the plant kingdom. This included flowering plants possessing seeds enclosed in capsules, distinguished from his Gymnospermae, or flowering plants with achenial or schizo-carpic fruits, the whole fruit or each of its pieces being here regarded as a seed and naked. The term and its antonym were maintained by Carl Linnaeus with the same sense, but with restricted application, in the names of the orders of his class Didynamia. Its use with any approach to its modern scope became possible only after 1827, when Robert Brown established the existence of truly naked ovules in the Cycadeae and Coniferae, and applied to them the name Gymnosperms.[citation needed] From that time onward, as long as these Gymnosperms were, as was usual, reckoned as dicotyledonous flowering plants, the term Angiosperm was used antithetically by botanical writers, with varying scope, as a group-name for other dicotyledonous plants.
Why did Robert Brown use the term dicotyledonous?
Answer:
unanswerable