sentence-transformers/squad huggingface dataset:
Passage: Hydrogen can be prepared in several different ways, but economically the most important processes involve removal of hydrogen from hydrocarbons. Commercial bulk hydrogen is usually produced by the steam reforming of natural gas. At high temperatures (1000–1400 K, 700–1100 °C or 1300–2000 °F), steam (water vapor) reacts with methane to yield carbon monoxide and H 2.

Question: The most economical way to prepare hydrogen involves removing it from what?

Question: What temperature is needed for steam to react with methane?
Passage: This reaction is favored at low pressures but is nonetheless conducted at high pressures (2.0 MPa, 20 atm or 600 inHg). This is because high-pressure H 2 is the most marketable product and Pressure Swing Adsorption (PSA) purification systems work better at higher pressures. The product mixture is known as "synthesis gas" because it is often used directly for the production of methanol and related compounds. Hydrocarbons other than methane can be used to produce synthesis gas with varying product ratios. One of the many complications to this highly optimized technology is the formation of coke or carbon:

Question: At what pressure does PSA work best in?

Question: What is synthesis gas used for?

Question: Besides methane, what else can be used to produce synthesis gas?
Passage: Consequently, steam reforming typically employs an excess of H 2O. Additional hydrogen can be recovered from the steam by use of carbon monoxide through the water gas shift reaction, especially with an iron oxide catalyst. This reaction is also a common industrial source of carbon dioxide:

Question: How can it be recovered through steam?
Passage: Hydrogen is sometimes produced and consumed in the same industrial process, without being separated. In the Haber process for the production of ammonia, hydrogen is generated from natural gas. Electrolysis of brine to yield chlorine also produces hydrogen as a co-product.

Question: When hydrogen is generated from natural gas, what des it produce?

Question: How is hydrogen produced as a co product?
Passage: There are more than 200 thermochemical cycles which can be used for water splitting, around a dozen of these cycles such as the iron oxide cycle, cerium(IV) oxide–cerium(III) oxide cycle, zinc zinc-oxide cycle, sulfur-iodine cycle, copper-chlorine cycle and hybrid sulfur cycle are under research and in testing phase to produce hydrogen and oxygen from water and heat without using electricity. A number of laboratories (including in France, Germany, Greece, Japan, and the USA) are developing thermochemical methods to produce hydrogen from solar energy and water.

Question: What are the thermochemical cycyles in a testing phase for?

Question: What are labs trying to produce hydrogen from?

Question: What countries are testing this?
Passage: Under anaerobic conditions, iron and steel alloys are slowly oxidized by the protons of water concomitantly reduced in molecular hydrogen (H 2). The anaerobic corrosion of iron leads first to the formation of ferrous hydroxide (green rust) and can be described by the following reaction:

Question: What condition is iron and steel alloys slowly oxidized?

Question: What does the anaerobic corrosion of iron lead to?

Question: What is another name for formation of ferrous hydroxide?
Passage: In its turn, under anaerobic conditions, the ferrous hydroxide (Fe(OH) 2 ) can be oxidized by the protons of water to form magnetite and molecular hydrogen. This process is described by the Schikorr reaction:

Question: Under what condition can ferrous hydroxide be oxidized?

Question: What does this process form?

Question: What reaction describes this process?
Passage: In the absence of atmospheric oxygen (O 2), in deep geological conditions prevailing far away from Earth atmosphere, hydrogen (H 2) 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 (Fe 2SiO 4, the olivine iron-endmember). The corresponding reaction leading to the formation of magnetite (Fe 3O 4), quartz (SiO 2) and hydrogen (H 2) is the following:

Question: How is hydrogen produced when there is no atmospheric oxygen?

Question: Where do you find silicate?
Passage: From all the fault gases formed in power transformers, hydrogen is the most common and is generated under most fault conditions; thus, formation of hydrogen is an early indication of serious problems in the transformer's life cycle.

Question: What is the most common gas found in power tranformers?
Passage: Large quantities of H 2 are needed in the petroleum and chemical industries. The largest application of H 2 is for the processing ("upgrading") of fossil fuels, and in the production of ammonia. The key consumers of H 2 in the petrochemical plant include hydrodealkylation, hydrodesulfurization, and hydrocracking. H 2 has several other important uses. H 2 is used as a hydrogenating agent, particularly in increasing the level of saturation of unsaturated fats and oils (found in items such as margarine), and in the production of methanol. It is similarly the source of hydrogen in the manufacture of hydrochloric acid. H 2 is also used as a reducing agent of metallic ores.

Question: Where are large quantities of H2 needed?

Question: What are the consumers of H2 in petrochemical plant?
Passage: Hydrogen is highly soluble in many rare earth and transition metals and is soluble in both nanocrystalline and amorphous metals. Hydrogen solubility in metals is influenced by local distortions or impurities in the crystal lattice. These properties may be useful when hydrogen is purified by passage through hot palladium disks, but the gas's high solubility is a metallurgical problem, contributing to the embrittlement of many metals, complicating the design of pipelines and storage tanks.

Question: Where is hydrogen highly soluble?

Question: Where can you find soluble hydrogen?

Question: What influences hydrogens solubility in metals?

Question: When are these useful?

Question: When is it damaging?
Passage: Apart from its use as a reactant, H 2 has wide applications in physics and engineering. It is used as a shielding gas in welding methods such as atomic hydrogen welding. H2 is used as the rotor coolant in electrical generators at power stations, because it has the highest thermal conductivity of any gas. Liquid H2 is used in cryogenic research, including superconductivity studies. Because H 2 is lighter than air, having a little more than 1⁄14 of the density of air, it was once widely used as a lifting gas in balloons and airships.

Question: Where else is H2 applied?

Question: How is H2 used in electrical generators at power stations?

Question: Why is it used as the rotor coolant?

Question: What research uses liquid H2?
Passage: In more recent applications, hydrogen is used pure or mixed with nitrogen (sometimes called forming gas) as a tracer gas for minute leak detection. Applications can be found in the automotive, chemical, power generation, aerospace, and telecommunications industries. Hydrogen is an authorized food additive (E 949) that allows food package leak testing among other anti-oxidizing properties.

Question: Why would one use hydrogen mixed with nitrogen?

Question: What industries can you find these applications?

Question: How is hydrogen used as a food additive?
Passage: Hydrogen's rarer isotopes also each have specific applications. Deuterium (hydrogen-2) is used in nuclear fission applications as a moderator to slow neutrons, and in nuclear fusion reactions. Deuterium compounds have applications in chemistry and biology in studies of reaction isotope effects. Tritium (hydrogen-3), produced in nuclear reactors, is used in the production of hydrogen bombs, as an isotopic label in the biosciences, and as a radiation source in luminous paints.

Question: What isotope is used in nuclear fission?

Question: Where is tritium produced?

Question: What is tritium used for?
Passage: Hydrogen is commonly used in power stations as a coolant in generators due to a number of favorable properties that are a direct result of its light diatomic molecules. These include low density, low viscosity, and the highest specific heat and thermal conductivity of all gases.

Question: How is hydrogen used at power stations?

Question: Why is it used as a coolant?

Question: What are these properties?
Passage: Hydrogen is not an energy resource, except in the hypothetical context of commercial nuclear fusion power plants using deuterium or tritium, a technology presently far from development. The Sun's energy comes from nuclear fusion of hydrogen, but this process is difficult to achieve controllably on Earth. Elemental hydrogen from solar, biological, or electrical sources require more energy to make it than is obtained by burning it, so in these cases hydrogen functions as an energy carrier, like a battery. Hydrogen may be obtained from fossil sources (such as methane), but these sources are unsustainable.

Question: Is Hydrogen considered an energy resource?

Question: Where does the sun get its energy from?

Question: How does hydrogen function when it s burned?
Passage: The energy density per unit volume of both liquid hydrogen and compressed hydrogen gas at any practicable pressure is significantly less than that of traditional fuel sources, although the energy density per unit fuel mass is higher. Nevertheless, elemental hydrogen has been widely discussed in the context of energy, as a possible future carrier of energy on an economy-wide scale. For example, CO 2 sequestration followed by carbon capture and storage could be conducted at the point of H 2 production from fossil fuels. Hydrogen used in transportation would burn relatively cleanly, with some NOx emissions, but without carbon emissions. However, the infrastructure costs associated with full conversion to a hydrogen economy would be substantial. Fuel cells can convert hydrogen and oxygen directly to electricity more efficiently than internal combustion engines.

Question: What form of hydrogen has been discussed as a ussage for fuel?
Passage: Hydrogen is employed to saturate broken ("dangling") bonds of amorphous silicon and amorphous carbon that helps stabilizing material properties. It is also a potential electron donor in various oxide materials, including ZnO, SnO2, CdO, MgO, ZrO2, HfO2, La2O3, Y2O3, TiO2, SrTiO3, LaAlO3, SiO2, Al2O3, ZrSiO4, HfSiO4, and SrZrO3.

Question: Why is hydrogen employed?

Question: How is hydrogen used in oxide materials?

Question: What oxide materials use hydrogen as an electron donor?
Passage: H2 is a product of some types of anaerobic metabolism and is produced by several microorganisms, usually via reactions catalyzed by iron- or nickel-containing enzymes called hydrogenases. These enzymes catalyze the reversible redox reaction between H2 and its component two protons and two electrons. Creation of hydrogen gas occurs in the transfer of reducing equivalents produced during pyruvate fermentation to water. The natural cycle of hydrogen production and consumption by organisms is called the hydrogen cycle.

Question: What enzymes are used to produce H2?

Question: When does hydrogen gas occur?

Question: What is the natural cycle of hydrogen production and consumption by organisms called?
Passage: Water splitting, in which water is decomposed into its component protons, electrons, and oxygen, occurs in the light reactions in all photosynthetic organisms. Some such organisms, including the alga Chlamydomonas reinhardtii and cyanobacteria, have evolved a second step in the dark reactions in which protons and electrons are reduced to form H2 gas by specialized hydrogenases in the chloroplast. Efforts have been undertaken to genetically modify cyanobacterial hydrogenases to efficiently synthesize H2 gas even in the presence of oxygen. Efforts have also been undertaken with genetically modified alga in a bioreactor.

Question: What is the decomposition of water into its components called?

Question: Where does water splitting occur?

Question: What organisms can form H2 gas?

Question: How are these gases formed?
Passage: Hydrogen poses a number of hazards to human safety, from potential detonations and fires when mixed with air to being an asphyxiant in its pure, oxygen-free form. In addition, liquid hydrogen is a cryogen and presents dangers (such as frostbite) associated with very cold liquids. Hydrogen dissolves in many metals, and, in addition to leaking out, may have adverse effects on them, such as hydrogen embrittlement, leading to cracks and explosions. Hydrogen gas leaking into external air may spontaneously ignite. Moreover, hydrogen fire, while being extremely hot, is almost invisible, and thus can lead to accidental burns.

Question: What threats can hydrogen cause to human saftey?

Question: What can hydrogen embrittlement lead to?
Passage: Even interpreting the hydrogen data (including safety data) is confounded by a number of phenomena. Many physical and chemical properties of hydrogen depend on the parahydrogen/orthohydrogen ratio (it often takes days or weeks at a given temperature to reach the equilibrium ratio, for which the data is usually given). Hydrogen detonation parameters, such as critical detonation pressure and temperature, strongly depend on the container geometry.

Question: What do physical and chemical properties of hydrogen depend on?

Question: How long can it take to reach the equilibrium ratio?

Question: What do Hydrogen detonation parameters depend on?
Passage: A web browser (commonly referred to as a browser) is a software application for retrieving, presenting, and traversing information resources on the World Wide Web. An information resource is identified by a Uniform Resource Identifier (URI/URL) and may be a web page, image, video or other piece of content. Hyperlinks present in resources enable users easily to navigate their browsers to related resources.

Question: What do people typically call a web browser?

Question: What platform is a browser used on?

Question: What does URL mean?

Question: What allows a person to direct their browser to a resource?
Passage: Although browsers are primarily intended to use the World Wide Web, they can also be used to access information provided by web servers in private networks or files in file systems.

Question: The primary function of a browser is to use what?

Question: In addition to accessing the Internet, browsers can also access info that is put there by web servers in what?

Question: A browser can also access files where?
Passage: The first web browser was invented in 1990 by Sir Tim Berners-Lee. Berners-Lee is the director of the World Wide Web Consortium (W3C), which oversees the Web's continued development, and is also the founder of the World Wide Web Foundation. His browser was called WorldWideWeb and later renamed Nexus.

Question: When was the first browser created?

Question: Who invented the first browser?

Question: What was Berners-Lee a director of?

Question: What organization did Berners-Lee create?
Passage: In 1993, browser software was further innovated by Marc Andreessen with the release of Mosaic, "the world's first popular browser", which made the World Wide Web system easy to use and more accessible to the average person. Andreesen's browser sparked the internet boom of the 1990s. The introduction of Mosaic in 1993 – one of the first graphical web browsers – led to an explosion in web use. Andreessen, the leader of the Mosaic team at National Center for Supercomputing Applications (NCSA), soon started his own company, named Netscape, and released the Mosaic-influenced Netscape Navigator in 1994, which quickly became the world's most popular browser, accounting for 90% of all web use at its peak (see usage share of web browsers).

Question: Who released Mosaic?

Question: When was Mosaic released?

Question: When Andreessen left the company he worked for, what new company did he start?

Question: What browser did Andreessen release in 1994?
Passage: Microsoft responded with its Internet Explorer in 1995, also heavily influenced by Mosaic, initiating the industry's first browser war. Bundled with Windows, Internet Explorer gained dominance in the web browser market; Internet Explorer usage share peaked at over 95% by 2002.

Question: Who released the Internet Explorer browser?

Question: When did Microsoft release Internet Explorer?

Question: The release of Internet Explorer started the first what?

Question: What was bundled with Internet Explorer?
Passage: Opera debuted in 1996; it has never achieved widespread use, having less than 2% browser usage share as of February 2012 according to Net Applications. Its Opera-mini version has an additive share, in April 2011 amounting to 1.1% of overall browser use, but focused on the fast-growing mobile phone web browser market, being preinstalled on over 40 million phones. It is also available on several other embedded systems, including Nintendo's Wii video game console.

Question: Opera was introduced in what year?

Question: What accounted for 1.1% of browser use in April 2011?

Question: Opera focused on which quickly growing market?

Question: Opera is also available on which video game console?
Passage: In 1998, Netscape launched what was to become the Mozilla Foundation in an attempt to produce a competitive browser using the open source software model. That browser would eventually evolve into Firefox, which developed a respectable following while still in the beta stage of development; shortly after the release of Firefox 1.0 in late 2004, Firefox (all versions) accounted for 7% of browser use. As of August 2011, Firefox has a 28% usage share.

Question: What did Netscape launch in 1998?

Question: Netscape wanted to have a competitive browser using what?

Question: What was the resulting browser for the Mozilla Foundation?

Question: When was Firefox released?
Passage: Apple's Safari had its first beta release in January 2003; as of April 2011, it had a dominant share of Apple-based web browsing, accounting for just over 7% of the entire browser market.

Question: When was the first beta release for Safari?

Question: Who created Safari?
Passage: The most recent major entrant to the browser market is Chrome, first released in September 2008. Chrome's take-up has increased significantly year by year, by doubling its usage share from 8% to 16% by August 2011. This increase seems largely to be at the expense of Internet Explorer, whose share has tended to decrease from month to month. In December 2011, Chrome overtook Internet Explorer 8 as the most widely used web browser but still had lower usage than all versions of Internet Explorer combined. Chrome's user-base continued to grow and in May 2012, Chrome's usage passed the usage of all versions of Internet Explorer combined. By April 2014, Chrome's usage had hit 45%.

Question: Which browser is the newest to enter the field?

Question: When was Chrome released?

Question: As Chrome usage increases, which browser usage has continued to decrease?

Question: When did Chrome become more used than all versions of Internet Explorer?
Passage: Internet Explorer, on the other hand, was bundled free with the Windows operating system (and was also downloadable free), and therefore it was funded partly by the sales of Windows to computer manufacturers and direct to users. Internet Explorer also used to be available for the Mac. It is likely that releasing IE for the Mac was part of Microsoft's overall strategy to fight threats to its quasi-monopoly platform dominance - threats such as web standards and Java - by making some web developers, or at least their managers, assume that there was "no need" to develop for anything other than Internet Explorer. In this respect, IE may have contributed to Windows and Microsoft applications sales in another way, through "lock-in" to Microsoft's browser.

Question: What was bundled for free with the Windows OS?

Question: Internet Explorer was partially funded in what two ways?

Question: What other OS could use Internet Explorer?
Passage: In January 2009, the European Commission announced it would investigate the bundling of Internet Explorer with Windows operating systems from Microsoft, saying "Microsoft's tying of Internet Explorer to the Windows operating system harms competition between web browsers, undermines product innovation and ultimately reduces consumer choice." Microsoft Corp v Commission

Question: Who investigated the bundling of the IE browser with Windows OS?

Question: When did the European Commission say they would investigate the bundling?

Question: The Commission felt that bundling the browser with Windows computers harmed what?

Question: The Commission felt that the bundling undermined what?
Passage: Safari and Mobile Safari were likewise always included with OS X and iOS respectively, so, similarly, they were originally funded by sales of Apple computers and mobile devices, and formed part of the overall Apple experience to customers.

Question: What browser was automatically included with OS X?
Passage: Today, most commercial web browsers are paid by search engine companies to make their engine default, or to include them as another option. For example, Google pays Mozilla, the maker of Firefox, to make Google Search the default search engine in Firefox. Mozilla makes enough money from this deal that it does not need to charge users for Firefox. In addition, Google Search is also (as one would expect) the default search engine in Google Chrome. Users searching for websites or items on the Internet would be led to Google's search results page, increasing ad revenue and which funds development at Google and of Google Chrome.

Question: Which company pays Firefox to make their search engine the default on their browser?

Question: What other browser has Google as the default search engine?

Question: The increased revenue funds what, in addition to Google?
Passage: The primary purpose of a web browser is to bring information resources to the user ("retrieval" or "fetching"), allowing them to view the information ("display", "rendering"), and then access other information ("navigation", "following links").

Question: What is the main use of a browser?
Passage: This process begins when the user inputs a Uniform Resource Locator (URL), for example http://en.wikipedia.org/, into the browser. The prefix of the URL, the Uniform Resource Identifier or URI, determines how the URL will be interpreted. The most commonly used kind of URI starts with http: and identifies a resource to be retrieved over the Hypertext Transfer Protocol (HTTP). Many browsers also support a variety of other prefixes, such as https: for HTTPS, ftp: for the File Transfer Protocol, and file: for local files. Prefixes that the web browser cannot directly handle are often handed off to another application entirely. For example, mailto: URIs are usually passed to the user's default e-mail application, and news: URIs are passed to the user's default newsgroup reader.

Question: What does URL stand for?

Question: What is the determining factor in how a URL will be interpreted?

Question: What does http stand for?

Question: What does ftp stand for?

Question: A news: prefix is given to the user's what?
Passage: In the case of http, https, file, and others, once the resource has been retrieved the web browser will display it. HTML and associated content (image files, formatting information such as CSS, etc.) is passed to the browser's layout engine to be transformed from markup to an interactive document, a process known as "rendering". Aside from HTML, web browsers can generally display any kind of content that can be part of a web page. Most browsers can display images, audio, video, and XML files, and often have plug-ins to support Flash applications and Java applets. Upon encountering a file of an unsupported type or a file that is set up to be downloaded rather than displayed, the browser prompts the user to save the file to disk.

Question: What is it called when content is changed from markup to an interactive document?

Question: Browsers typically have plug-ins to support what?