Problem: Incandescent light bulb:

The spectrum emitted by a blackbody radiator at temperatures of incandescent bulbs does not match the sensitivity characteristics of the human eye; the light emitted does not appear white, and most is not in the range of wavelengths at which the eye is most sensitive. Tungsten filaments radiate mostly infrared radiation at temperatures where they remain solid below 3,695 K (3,422 C; 6,191 F). Donald L. Klipstein explains it this way: "An ideal thermal radiator produces visible light most efficiently at temperatures around 6,300 C (6,600 K; 11,400 F). Even at this high temperature, a lot of the radiation is either infrared or ultraviolet, and the theoretical luminous efficacy (LER) is 95 lumens per watt." No known material can be used as a filament at this ideal temperature, which is hotter than the sun's surface. An upper limit for incandescent lamp luminous efficacy (LER) is around 52 lumens per watt, the theoretical value emitted by tungsten at its melting point.

What is the lower limit for LER of an incandescent lamp?
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A: unanswerable

Problem: Mianyang Hi-Tech Industrial Development Zone was established in 1992, with a planned area of 43 km2 (17 sq mi). The zone is situated 96 kilometers away from Chengdu, and is 8 km (5.0 mi) away from Mianyang Airport. Since its establishment, the zone accumulated 177.4 billion yuan of industrial output, 46.2 billion yuan of gross domestic product, fiscal revenue 6.768 billion yuan. There are more than 136 high-tech enterprises in the zone and they accounted for more than 90% of the total industrial output.
What is the distance between the Mianyang Hi-Tech Industrial Development Zone and Mianyang Airport?
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Answer: 8 km

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
There are a multitude of supporters as well as opponents to the policy of affirmative action. Many presidents throughout the last century have failed to take a very firm stance on the policy, and the public has had to discern the president's opinion for themselves. Bill Clinton, however, made his stance on affirmative action very clear in a speech on July 19, 1995, nearly two and a half years after his inauguration. In his speech, he discussed the history in the United States that brought the policy into fruition: slavery, Jim Crow, and segregation. Clinton also mentioned a point similar to President Lyndon B. Johnson's "Freedom is not Enough" speech, and declared that just outlawing discrimination in the country would not be enough to give everyone in America equality. He addressed the arguments that affirmative action hurt the white middle class and said that the policy was not the source of their problems. Clinton plainly outlined his stance on affirmative action, saying:
Which speech did Bill Clinton's speech draw parallels to?
A: President Lyndon B. Johnson's "Freedom is not Enough"

Context and question: All Freemasons begin their journey in the "craft" by being progressively initiated, passed and raised into the three degrees of Craft, or Blue Lodge Masonry. During these three rituals, the candidate is progressively taught the meanings of the Lodge symbols, and entrusted with grips, signs and words to signify to other Masons that he has been so initiated. The initiations are part allegory and part lecture, and revolve around the construction of the Temple of Solomon, and the artistry and death of his chief architect, Hiram Abiff. The degrees are those of Entered apprentice, Fellowcraft and Master Mason. While many different versions of these rituals exist, with at least two different lodge layouts and versions of the Hiram myth, each version is recognisable to any Freemason from any jurisdiction.
What is the final of the three steps of Freemasonry?
Answer: Master Mason

Question: Battles which are particularly notable to the Canadian military include the Battle of Vimy Ridge, the Dieppe Raid, the Battle of Ortona, the Battle of Passchendaele, the Normandy Landings, the Battle for Caen, the Battle of the Scheldt, the Battle of Britain, the Battle of the Atlantic, the strategic bombing of German cities, and more recently the Battle of Medak Pocket, in Croatia.
Is there an answer to this question: Who are the Battle of Normandy Landings and the Vimy Ridge Raid notable to?

Answer: unanswerable

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Lossless audio compression produces a representation of digital data that decompress to an exact digital duplicate of the original audio stream, unlike playback from lossy compression techniques such as Vorbis and MP3. Compression ratios are around 5060% of original size, which is similar to those for generic lossless data compression. Lossless compression is unable to attain high compression ratios due to the complexity of waveforms and the rapid changes in sound forms. Codecs like FLAC, Shorten and TTA use linear prediction to estimate the spectrum of the signal. Many of these algorithms use convolution with the filter [-1 1] to slightly whiten or flatten the spectrum, thereby allowing traditional lossless compression to work more efficiently. The process is reversed upon decompression.
What are around 50-60% of the spectrum?
A:
unanswerable