[Q]: Extract the answer to the question from the following context. Question: Rail is a type of? Context: Mass transit in New York City, most of which runs 24 hours a day, accounts for one in every three users of mass transit in the United States, and two-thirds of the nation's rail riders live in the New York City Metropolitan Area.
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[A]: transit

[Q]: Extract the answer to the question from the following context. Question: In what reaction will the formation of organomagnesium halide fail if water is present? Context: There are many important organozinc compounds. Organozinc chemistry is the science of organozinc compounds describing their physical properties, synthesis and reactions. Among important applications is the Frankland-Duppa Reaction in which an oxalate ester(ROCOCOOR) reacts with an alkyl halide R'X, zinc and hydrochloric acid to the -hydroxycarboxylic esters RR'COHCOOR, the Reformatskii reaction which converts -halo-esters and aldehydes to -hydroxy-esters, the SimmonsSmith reaction in which the carbenoid (iodomethyl)zinc iodide reacts with alkene(or alkyne) and converts them to cyclopropane, the Addition reaction of organozinc compounds to carbonyl compounds. The Barbier reaction (1899) is the zinc equivalent of the magnesium Grignard reaction and is better of the two. In presence of just about any water the formation of the organomagnesium halide will fail, whereas the Barbier reaction can even take place in water. On the downside organozincs are much less nucleophilic than Grignards, are expensive and difficult to handle. Commercially available diorganozinc compounds are dimethylzinc, diethylzinc and diphenylzinc. In one study the active organozinc compound is obtained from much cheaper organobromine precursors:
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[A]: magnesium Grignard reaction

[Q]: Extract the answer to the question from the following context. Question: Which month is colder in Atlantic City, July or January? Context: Summers are typically warm and humid with a July daily average of 75.6 F (24.2 C). During this time, the city gets a sea breeze off the ocean that often makes daytime temperatures much cooler than inland areas, making Atlantic City a prime place for beating the summer heat from June through September. Average highs even just a few miles west of Atlantic City exceed 85 F (29 C) in July. Near the coast, temperatures reach or exceed 90 F (32 C) on an average of only 6.8 days a year, but this reaches 21 days at nearby Atlantic City Int'l.[a] Winters are cool, with January averaging 35.5 F (2 C). Spring and autumn are erratic, although they are usually mild with low humidity. The average window for freezing temperatures is November 20 to March 25, allowing a growing season of 239 days. Extreme temperatures range from 9 F (23 C) on February 9, 1934 to 104 F (40 C) on August 7, 1918.[b]
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[A]: January

[Q]: Extract the answer to the question from the following context. Question: If there is hydrogen present, what is not? Context: In the absence of atmospheric oxygen (O2), in deep geological conditions prevailing far away from Earth atmosphere, hydrogen (H2) is produced during the process of serpentinization by the anaerobic oxidation by the water protons (H+) of the ferrous (Fe2+) silicate present in the crystal lattice of the fayalite (Fe2SiO4, the olivine iron-endmember). The corresponding reaction leading to the formation of magnetite (Fe3O4), quartz (SiO2) and hydrogen (H2) is the following:
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[A]:
atmospheric oxygen (O2)