Problem: Antarctica is colder than the Arctic for three reasons. First, much of the continent is more than 3,000 m (9,800 ft) above sea level, and temperature decreases with elevation in the troposphere. Second, the Arctic Ocean covers the north polar zone: the ocean's relative warmth is transferred through the icepack and prevents temperatures in the Arctic regions from reaching the extremes typical of the land surface of Antarctica. Third, the Earth is at aphelion in July (i.e., the Earth is farthest from the Sun in the Antarctic winter), and the Earth is at perihelion in January (i.e., the Earth is closest to the Sun in the Antarctic summer). The orbital distance contributes to a colder Antarctic winter (and a warmer Antarctic summer) but the first two effects have more impact.
What contributes to the Antarctic cold?
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Answer: orbital distance


Problem: Uranium is a chemical element with symbol U and atomic number 92. It is a silvery-white metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weakly radioactive because all its isotopes are unstable (with half-lives of the six naturally known isotopes, uranium-233 to uranium-238, varying between 69 years and 4.5 billion years). The most common isotopes of uranium are uranium-238 (which has 146 neutrons and accounts for almost 99.3% of the uranium found in nature) and uranium-235 (which has 143 neutrons, accounting for 0.7% of the element found naturally). Uranium has the second highest atomic weight of the primordially occurring elements, lighter only than plutonium. Its density is about 70% higher than that of lead, but slightly lower than that of gold or tungsten. It occurs naturally in low concentrations of a few parts per million in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite.
What isn't uranium's symbol on the Periodic Table of Elements?
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Answer: unanswerable


Problem: The European powers recognized the islands as part of the Spanish East Indies in 1874. However, Spain sold the islands to the German Empire in 1884, and they became part of German New Guinea in 1885. In World War I the Empire of Japan occupied the Marshall Islands, which in 1919 the League of Nations combined with other former German territories to form the South Pacific Mandate. In World War II, the United States conquered the islands in the Gilbert and Marshall Islands campaign. Along with other Pacific Islands, the Marshall Islands were then consolidated into the Trust Territory of the Pacific Islands governed by the US. Self-government was achieved in 1979, and full sovereignty in 1986, under a Compact of Free Association with the United States. Marshall Islands has been a United Nations member state since 1991.
What European nation owned the Marshall Islands in 1874?
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Answer:
Spain