Problem: Uranium-238 is the most stable isotope of uranium, with a half-life of about 4.468109 years, roughly the age of the Earth. Uranium-235 has a half-life of about 7.13108 years, and uranium-234 has a half-life of about 2.48105 years. For natural uranium, about 49% of its alpha rays are emitted by each of 238U atom, and also 49% by 234U (since the latter is formed from the former) and about 2.0% of them by the 235U. When the Earth was young, probably about one-fifth of its uranium was uranium-235, but the percentage of 234U was probably much lower than this.
What isotope of uranium has the least stability?
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Answer: unanswerable

Problem: Eventually, the Licchavi ruler Gunakamadeva merged Koligram and Dakshin Koligram, founding the city of Kathmandu. The city was designed in the shape of Chandrahrasa, the sword of Manjushri. The city was surrounded by eight barracks guarded by Ajimas. One of these barracks is still in use at Bhadrakali (in front of Singha Durbar). The city served as an important transit point in the trade between India and Tibet, leading to tremendous growth in architecture. Descriptions of buildings such as Managriha, Kailaskut Bhawan, and Bhadradiwas Bhawan have been found in the surviving journals of travelers and monks who lived during this era. For example, the famous 7th-century Chinese traveller Xuanzang described Kailaskut Bhawan, the palace of the Licchavi king Amshuverma. The trade route also led to cultural exchange as well. The artistry of the Newar peoplethe indigenous inhabitants of the Kathmandu Valleybecame highly sought after during this era, both within the Valley and throughout the greater Himalayas. Newar artists travelled extensively throughout Asia, creating religious art for their neighbors. For example, Araniko led a group of his compatriot artists through Tibet and China. Bhrikuti, the princess of Nepal who married Tibetan monarch Songtsan Gampo, was instrumental in introducing Buddhism to Tibet.
How many barracks guarded ancient Kathmandu?
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Answer: eight

Problem: Interracial relationships have had a long history in North America and the United States, beginning with the intermixing of European explorers and soldiers, who took native women as companions. After European settlement increased, traders and fur trappers often married or had unions with women of native tribes. In the 17th century, faced with a continuing, critical labor shortage, colonists primarily in the Chesapeake Bay Colony, imported Africans as laborers, sometimes as indentured servants and, increasingly, as slaves. African slaves were also imported into New York and other northern ports by the Dutch and later English. Some African slaves were freed by their masters during these early years.
Who first imported slaves to New York?
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Answer:
the Dutch