Problem: On 2 December 1942, as part of the Manhattan Project, another team led by Enrico Fermi was able to initiate the first artificial self-sustained nuclear chain reaction, Chicago Pile-1. Working in a lab below the stands of Stagg Field at the University of Chicago, the team created the conditions needed for such a reaction by piling together 400 short tons (360 metric tons) of graphite, 58 short tons (53 metric tons) of uranium oxide, and six short tons (5.5 metric tons) of uranium metal, a majority of which was supplied by Westinghouse Lamp Plant in a makeshift production process.
How many metric tons of uranium oxide was used in Chicago Pile-21?
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Answer: unanswerable

Problem: Various connectors have been used for smaller devices such as digital cameras, smartphones, and tablet computers. These include the now-deprecated (i.e. de-certified but standardized) mini-A and mini-AB connectors; mini-B connectors are still supported, but are not OTG-compliant (On The Go, used in mobile devices). The mini-B USB connector was standard for transferring data to and from the early smartphones and PDAs. Both mini-A and mini-B plugs are approximately 3 by 7 mm; the mini-A connector and the mini-AB receptacle connector were deprecated on 23 May 2007.
When were the mini-A connector and and the mini-AB receptacle connector depreceated?
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Answer: 23 May 2007

Problem: Bipolar transistors are so named because they conduct by using both majority and minority carriers. The bipolar junction transistor, the first type of transistor to be mass-produced, is a combination of two junction diodes, and is formed of either a thin layer of p-type semiconductor sandwiched between two n-type semiconductors (an npn transistor), or a thin layer of n-type semiconductor sandwiched between two p-type semiconductors (a pnp transistor). This construction produces two pn junctions: a baseemitter junction and a basecollector junction, separated by a thin region of semiconductor known as the base region (two junction diodes wired together without sharing an intervening semiconducting region will not make a transistor).
What is the name for a layer of n-type semiconductor set between two p-type semiconductors?
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Answer:
pnp transistor