Problem: Hydrogen:

The energy levels of hydrogen can be calculated fairly accurately using the Bohr model of the atom, which conceptualizes the electron as "orbiting" the proton in analogy to the Earth's orbit of the Sun. However, the electromagnetic force attracts electrons and protons to one another, while planets and celestial objects are attracted to each other by gravity. Because of the discretization of angular momentum postulated in early quantum mechanics by Bohr, the electron in the Bohr model can only occupy certain allowed distances from the proton, and therefore only certain allowed energies.

What attracts planets and celestial items?
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A: gravity


Problem: London:

London's bus network is one of the largest in the world, running 24 hours a day, with about 8,500 buses, more than 700 bus routes and around 19,500 bus stops. In 2013, the network had more than 2 billion commuter trips per annum, more than the Underground. Around £850 million is taken in revenue each year. London has the largest wheelchair accessible network in the world and, from the 3rd quarter of 2007, became more accessible to hearing and visually impaired passengers as audio-visual announcements were introduced. The distinctive red double-decker buses are an internationally recognised trademark of London transport along with black cabs and the Tube.

How much revenue is generated yearly by London's public bus service?
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A: £850 million


Problem: Republic of the Congo:

During the Nazi occupation of France during World War II, Brazzaville functioned as the symbolic capital of Free France between 1940 and 1943. The Brazzaville Conference of 1944 heralded a period of major reform in French colonial policy. Congo benefited from the postwar expansion of colonial administrative and infrastructure spending as a result of its central geographic location within AEF and the federal capital at Brazzaville. It also received a local legislature after the adoption of the 1946 constitution that established the Fourth Republic.

What did the 1946 constitution establish Brazzaville as?
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A: the Fourth Republic


Problem: Beer:

The alcohol in beer comes primarily from the metabolism of sugars that are produced during fermentation. The quantity of fermentable sugars in the wort and the variety of yeast used to ferment the wort are the primary factors that determine the amount of alcohol in the final beer. Additional fermentable sugars are sometimes added to increase alcohol content, and enzymes are often added to the wort for certain styles of beer (primarily "light" beers) to convert more complex carbohydrates (starches) to fermentable sugars. Alcohol is a by-product of yeast metabolism and is toxic to the yeast; typical brewing yeast cannot survive at alcohol concentrations above 12% by volume. Low temperatures and too little fermentation time decreases the effectiveness of yeasts and consequently decreases the alcohol content.

What decreases wort content?
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A:
unanswerable