Problem: At high altitudes, Neptune's atmosphere is 80% hydrogen and 19% helium. A trace amount of methane is also present. Prominent absorption bands of methane exist at wavelengths above 600 nm, in the red and infrared portion of the spectrum. As with Uranus, this absorption of red light by the atmospheric methane is part of what gives Neptune its blue hue, although Neptune's vivid azure differs from Uranus's milder cyan. Because Neptune's atmospheric methane content is similar to that of Uranus, some unknown atmospheric constituent is thought to contribute to Neptune's colour.
What is Neptune's atmosphere made of?
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Answer: 80% hydrogen and 19% helium

Problem: The oldest known archaeological fragments of the immediate precursor to modern paper, date to the 2nd century BC in China. The pulp papermaking process is ascribed to Cai Lun, a 2nd-century AD Han court eunuch. With paper as an effective substitute for silk in many applications, China could export silk in greater quantity, contributing to a Golden Age.
What material did paper not replace upon its invention?
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Answer: unanswerable

Problem: Within London, both the City of London and the City of Westminster have city status and both the City of London and the remainder of Greater London are counties for the purposes of lieutenancies. The area of Greater London has incorporated areas that were once part of the historic counties of Middlesex, Kent, Surrey, Essex and Hertfordshire. London's status as the capital of England, and later the United Kingdom, has never been granted or confirmed officiallyby statute or in written form.[note 6]
For what reason are the City of London and Greater London considered to be counties?
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Answer:
for the purposes of lieutenancies