romikgosai/squad_modified huggingface dataset:
Voiced consonants are seldom actually aspirated. Symbols for voiced consonants followed by ⟨◌ʰ⟩, such as ⟨bʰ⟩, typically represent consonants with breathy voiced release (see below). In the grammatical tradition of Sanskrit, aspirated consonants are called voiceless aspirated, and breathy-voiced consonants are called voiced aspirated.

Questions and answers:
['
Q: What is not often aspirated?
A: Voiced consonants', '
Q: The symbol followed by bʰ would likely mean the consonant has what type of release?
A: breathy', '
Q: Voiced aspirated consonants are what type?
A: breathy-voiced']
There are no dedicated IPA symbols for degrees of aspiration and typically only two degrees are marked: unaspirated ⟨k⟩ and aspirated ⟨kʰ⟩. An old symbol for light aspiration was ⟨ʻ⟩, but this is now obsolete. The aspiration modifier letter may be doubled to indicate especially strong or long aspiration. Hence, the two degrees of aspiration in Korean stops are sometimes transcribed ⟨kʰ kʰʰ⟩ or ⟨kʻ⟩ and ⟨kʰ⟩, but they are usually transcribed [k] and [kʰ], with the details of voice-onset time given numerically.

Questions and answers:
['
Q: There are no IPA symbols for what?
A: degrees of aspiration', '
Q: What may be doubled to indicate a long aspiration?
A: aspiration modifier', '
Q: What language, according to the text, may need double stops to indicate aspiration length?
A: Korean', '
Q: How are voice-onset time details usually presented?
A: numerically']
Preaspirated consonants are marked by placing the aspiration modifier letter before the consonant symbol: ⟨ʰp⟩ represents the preaspirated bilabial stop.

Questions and answers:
['
Q: A preaspirated consonant is marked how?
A: placing the aspiration modifier letter before the consonant symbol', '
Q: What represents a preaspirated bilabial stop?
A: ⟨ʰp⟩']
Unaspirated or tenuis consonants are occasionally marked with the modifier letter for unaspiration ⟨◌˭⟩, a superscript equal sign: ⟨t˭⟩. Usually, however, unaspirated consonants are left unmarked: ⟨t⟩.

Questions and answers:
['
Q: How are unaspirated or tenuis consonants sometimes marked for unaspiration?
A: with the modifier letter', '
Q: What is the superscript equal sign?
A: ⟨t˭⟩', '
Q: Most often, unaspirated consonants are what?
A: left unmarked', '
Q: How are unaspirated consonants left unmarked?
A: ⟨t⟩']
Voiceless consonants are produced with the vocal folds open (spread) and not vibrating, and voiced consonants are produced when the vocal folds are fractionally closed and vibrating (modal voice). Voiceless aspiration occurs when the vocal cords remain open after a consonant is released. An easy way to measure this is by noting the consonant's voice-onset time, as the voicing of a following vowel cannot begin until the vocal cords close.

Questions and answers:
['
Q: What is created when the vocal folds are spread and do not vibrate?
A: Voiceless consonants', '
Q: What is created when vocal folds are slightly closed and vibrate?
A: voiced consonants', "
Q: What is it called when a person's vocal cords stay open after a consonant?
A: Voiceless aspiration"]
Phonetically in some languages, such as Navajo, aspiration of stops tends to be realised as voiceless velar airflow; aspiration of affricates is realised as an extended length of the frication.

Questions and answers:
['
Q: Aspiration of stops is seen as voiceless velar airflow in some languages, such as what?
A: Navajo', '
Q: In Navajo, the aspiration of affricates can be seen as what?
A: an extended length of the frication']
Aspirated consonants are not always followed by vowels or other voiced sounds. For example, in Eastern Armenian, aspiration is contrastive even word-finally, and aspirated consonants occur in consonant clusters. In Wahgi, consonants are aspirated only in final position.

Questions and answers:
['
Q: In Eastern Armenian, aspirated consonants occur in what?
A: consonant clusters', '
Q: Where are consonants aspirated in just the final position?
A: Wahgi']
Armenian and Cantonese have aspiration that lasts about as long as English aspirated stops, in addition to unaspirated stops. Korean has lightly aspirated stops that fall between the Armenian and Cantonese unaspirated and aspirated stops as well as strongly aspirated stops whose aspiration lasts longer than that of Armenian or Cantonese. (See voice-onset time.)

Questions and answers:
['
Q: As well as lasting as long as an English aspirated stop, the Armenian and Cantonese aspiration lasts as long as what?
A: unaspirated stops']
Aspiration varies with place of articulation. The Spanish voiceless stops /p t k/ have voice-onset times (VOTs) of about 5, 10, and 30 milliseconds, whereas English aspirated /p t k/ have VOTs of about 60, 70, and 80 ms. Voice-onset time in Korean has been measured at 20, 25, and 50 ms for /p t k/ and 90, 95, and 125 for /pʰ tʰ kʰ/.

Questions and answers:
['
Q: Aspiration alters with what?
A: place of articulation']
When aspirated consonants are doubled or geminated, the stop is held longer and then has an aspirated release. An aspirated affricate consists of a stop, fricative, and aspirated release. A doubled aspirated affricate has a longer hold in the stop portion and then has a release consisting of the fricative and aspiration.

Questions and answers:
['
Q: What happens when an aspirated consonant is doubled or geminated?
A: the stop is held longer and then has an aspirated release.', '
Q: What is comprised of a stop, fricative, and aspirated release?
A: An aspirated affricate']
Icelandic and Faroese have preaspirated [ʰp ʰt ʰk]; some scholars interpret these as consonant clusters as well. In Icelandic, preaspirated stops contrast with double stops and single stops:

Questions and answers:
['
Q: What two languages mentioned have have preaspirated [ʰp ʰt ʰk]?
A: Icelandic and Faroese', '
Q: What do scholars say the preaspirated [ʰp ʰt ʰk] are too?
A: consonant clusters', '
Q: What do preaspirated stops contrast with in Icelandic?
A: double stops and single stops']
Preaspirated stops also occur in most Sami languages; for example, in North Sami, the unvoiced stop and affricate phonemes /p/, /t/, /ts/, /tʃ/, /k/ are pronounced preaspirated ([ʰp], [ʰt] [ʰts], [ʰtʃ], [ʰk]) when they occur in medial or final position.

Questions and answers:
['
Q: The Sami tongue also has what?
A: Preaspirated stops', '
Q: Which Sami tongue has unvoiced stop and affricate phonemes pronounced preaspirated?
A: North Sami']
Although most aspirated obstruents in the world's language are stops and affricates, aspirated fricatives such as [sʰ], [fʰ] or [ɕʰ] have been documented in Korean, in a few Tibeto-Burman languages, in some Oto-Manguean languages, and in the Siouan language Ofo. Some languages, such as Choni Tibetan, have up to four contrastive aspirated fricatives [sʰ] [ɕʰ], [ʂʰ] and [xʰ].

Questions and answers:
['
Q: How many contrastive aspirated fricatives does Choni Tibetan have?
A: up to four']
True aspirated voiced consonants, as opposed to murmured (breathy-voice) consonants such as the [bʱ], [dʱ], [ɡʱ] that are common in the languages of India, are extremely rare. They have been documented in Kelabit Taa, and the Kx'a languages. Reported aspirated voiced stops, affricates and clicks are [b͡pʰ, d͡tʰ, d͡tsʰ, d͡tʃʰ, ɡ͡kʰ, ɢ͡qʰ, ᶢʘʰ, ᶢǀʰ, ᶢǁʰ, ᶢǃʰ, ᶢǂʰ].

Questions and answers:
['
Q: Indian languages commonly have murmured consonants instead of what?
A: True aspirated voiced consonants', '
Q: True aspirated consonants are considered what?
A: rare', "
Q: True aspirated consonants have been found in Kelabit Taa and what else?
A: Kx'a languages"]
Aspiration has varying significance in different languages. It is either allophonic or phonemic, and may be analyzed as an underlying consonant cluster.

Questions and answers:
['
Q: What has a different significance in various languages?
A: Aspiration', '
Q: What two forms can aspiration be in?
A: allophonic or phonemic']
In some languages, such as English, aspiration is allophonic. Stops are distinguished primarily by voicing, and voiceless stops are sometimes aspirated, while voiced stops are usually unaspirated.

Questions and answers:
['
Q: Aspiration is what, in English and some other languages?
A: allophonic', '
Q: How are stops distinguished?
A: voicing', '
Q: Voiceless stops are at times what?
A: aspirated', '
Q: Voiced stops are most often what?
A: unaspirated']
They are unaspirated for almost all speakers when immediately following word-initial s, as in spill, still, skill. After an s elsewhere in a word they are normally unaspirated as well, except sometimes in compound words. When the consonants in a cluster like st are analyzed as belonging to different morphemes (heteromorphemic) the stop is aspirated, but when they are analyzed as belonging to one morpheme the stop is unaspirated.[citation needed] For instance, distend has unaspirated [t] since it is not analyzed as two morphemes, but distaste has an aspirated middle [tʰ] because it is analyzed as dis- + taste and the word taste has an aspirated initial t.

Questions and answers:
['
Q: When following a word such as spill, they are what for most speakers?
A: unaspirated', '
Q: If the letter s is a different place in the word, it is typical unaspirated unless the word is what?
A: compound words', '
Q: If there is a cluster such as st and it belongs to different morphemes, the stop is what?
A: aspirated', '
Q: If the st belongs to one morpheme, then the stop is what?
A: unaspirated']
In many languages, such as Armenian, Korean, Thai, Indo-Aryan languages, Dravidian languages, Icelandic, Ancient Greek, and the varieties of Chinese, tenuis and aspirated consonants are phonemic. Unaspirated consonants like [p˭ s˭] and aspirated consonants like [pʰ ʰp sʰ] are separate phonemes, and words are distinguished by whether they have one or the other.

Questions and answers:
['
Q: In languages like Thai and Icelandic, tenuis and aspirated consonants are what?
A: phonemic', '
Q: [p˭ s˭] and [pʰ ʰp sʰ] are separate what?
A: phonemes']
In Danish and most southern varieties of German, the "lenis" consonants transcribed for historical reasons as ⟨b d ɡ⟩ are distinguished from their fortis counterparts ⟨p t k⟩, mainly in their lack of aspiration.

Questions and answers:
['
Q: How are lenis consonants distinguished from fortis consonants?
A: their lack of aspiration', '
Q: If the lenis are ⟨b d ɡ⟩, what are the fortis counterparts?
A: ⟨p t k⟩']
Standard Chinese (Mandarin) has stops and affricates distinguished by aspiration: for instance, /t tʰ/, /t͡s t͡sʰ/. In pinyin, tenuis stops are written with letters that represent voiced consonants in English, and aspirated stops with letters that represent voiceless consonants. Thus d represents /t/, and t represents /tʰ/.

Questions and answers:
['
Q: Mandarin has stops and affricates that are distinguished by what?
A: aspiration', '
Q: Tenuis stops have letters that are representative of English voiced consonant in what?
A: pinyin', '
Q: What kind of stops in pinyin are written with letters that representative of voiceless consonants?
A: aspirated stops']
Wu Chinese has a three-way distinction in stops and affricates: /p pʰ b/. In addition to aspirated and unaspirated consonants, there is a series of muddy consonants, like /b/. These are pronounced with slack or breathy voice: that is, they are weakly voiced. Muddy consonants as initial cause a syllable to be pronounced with low pitch or light (陽 yáng) tone.

Questions and answers:
['
Q: What has a three-way distinction in regards to stops and affricates?
A: Wu Chinese', '
Q: What is the actual distinction for Wu Chinese?
A: /p pʰ b/', '
Q: What is /b/ representative of, in addition to aspirated and unaspirated consonants?
A: Muddy consonants', '
Q: What kind of voice are muddy consonants pronounced with?
A: slack or breathy']
Many Indo-Aryan languages have aspirated stops. Sanskrit, Hindi, Bengali, Marathi, and Gujarati have a four-way distinction in stops: voiceless, aspirated, voiced, and breathy-voiced or voiced aspirated, such as /p pʰ b bʱ/. Punjabi has lost breathy-voiced consonants, which resulted in a tone system, and therefore has a distinction between voiceless, aspirated, and voiced: /p pʰ b/.

Questions and answers:
['
Q: How many distinctions in stops do languages like Bengali and Hindi have?
A: four', '
Q: What is another term for voice-aspirated?
A: breathy-voiced', '
Q: Which distinction has Punjabi lost?
A: breathy-voiced consonants']
Some of the Dravidian languages, such as Telugu, Tamil, Malayalam, and Kannada, have a distinction between voiced and voiceless, aspirated and unaspirated only in loanwords from Indo-Aryan languages. In native Dravidian words, there is no distinction between these categories and stops are underspecified for voicing and aspiration.

Questions and answers:
['
Q: Telegu, Kannada and others are considered to be some of the what languages?
A: Dravidian', '
Q: What has no distinction between the categories  of voiced, voiceless, aspirated and unaspirated?
A: native Dravidian words']
Western Armenian has a two-way distinction between aspirated and voiced: /tʰ d/. Western Armenian aspirated /tʰ/ corresponds to Eastern Armenian aspirated /tʰ/ and voiced /d/, and Western voiced /d/ corresponds to Eastern voiceless /t/.

Questions and answers:
['
Q: What language has two-way distinctions between aspirated and voiced?
A: Western Armenian', '
Q: Western Armenian /tʰ/ compares to eastern Armenian /tʰ/ and what?
A: /d/', '
Q: The Western Armenian voiced /d/ compares to the Eastern Armenian voiceless what?
A: /t/']
Some forms of Greek before the Koine Greek period are reconstructed as having aspirated stops. The Classical Attic dialect of Ancient Greek had a three-way distinction in stops like Eastern Armenian: /t tʰ d/. These stops were called ψιλά, δασέα, μέσα "thin, thick, middle" by Koine Greek grammarians.

Questions and answers:
['
Q: Early Greek (before Koine) have been redone with what?
A: aspirated stops.', '
Q: What Greek dialect had three-way stop distinction like Eastern Armenian?
A: Classical Attic', '
Q: Who referred to the Classical Attic dialect stops by the three distinctions?
A: Greek grammarians']
There were aspirated stops at three places of articulation: labial, coronal, and velar /pʰ tʰ kʰ/. Earlier Greek, represented by Mycenaean Greek, likely had a labialized velar aspirated stop /kʷʰ/, which later became labial, coronal, or velar depending on dialect and phonetic environment.

Questions and answers:
['
Q: What is the representation for the three places of articulation?
A: /pʰ tʰ kʰ/', '
Q: Earlier Greek was represented by what?
A: Mycenaean Greek', '
Q: Whether a stop was labial, coronal or velar depended on what two things?
A: dialect and phonetic environment']
The other Ancient Greek dialects, Ionic, Doric, Aeolic, and Arcadocypriot, likely had the same three-way distinction at one point, but Doric seems to have had a fricative in place of /tʰ/ in the Classical period, and the Ionic and Aeolic dialects sometimes lost aspiration (psilosis).

Questions and answers:
['
Q: Dialects such as Aeolic and Doric had how many distinctions that were the same at one point in time?
A: three', '
Q: Which two dialects lost aspiration at times?
A: Ionic and Aeolic', '
Q: Rather than /tʰ/, what did the Doric dialect have in place during the Classical period?
A: fricative']
Later, during the Koine Greek period, the aspirated and voiceless stops /tʰ d/ of Attic Greek lenited to voiceless and voiced fricatives, yielding /θ ð/ in Medieval and Modern Greek.

Questions and answers:
['
Q: Attic Greek lenited to what?
A: voiceless and voiced fricatives', '
Q: The lenited Attic Greek yielded /θ ð/ in what periods?
A: Medieval and Modern Greek']
The term aspiration sometimes refers to the sound change of debuccalization, in which a consonant is lenited (weakened) to become a glottal stop or fricative [ʔ h ɦ].

Questions and answers:
['
Q: Aspiration may refer to a sound change of what?
A: debuccalization', '
Q: Debuccalization is when consonants are weakened to become what?
A: glottal stop or fricative', '
Q: What is another term for a consonant being weakened?
A: lenited']
So-called voiced aspirated consonants are nearly always pronounced instead with breathy voice, a type of phonation or vibration of the vocal folds. The modifier letter ⟨◌ʰ⟩ after a voiced consonant actually represents a breathy-voiced or murmured dental stop, as with the "voiced aspirated" bilabial stop ⟨bʰ⟩ in the Indo-Aryan languages. This consonant is therefore more accurately transcribed as ⟨b̤⟩, with the diacritic for breathy voice, or with the modifier letter ⟨bʱ⟩, a superscript form of the symbol for the voiced glottal fricative ⟨ɦ⟩.

Questions and answers:
['
Q: What is breathy voice?
A: a type of phonation or vibration of the vocal folds', '
Q: The ⟨bʰ⟩ in the Indo-Aryan languages is better transcribed how for breathy voice?
A: ⟨b̤⟩, with the diacritic']
Some linguists restrict the double-dot subscript ⟨◌̤⟩ to murmured sonorants, such as vowels and nasals, which are murmured throughout their duration, and use the superscript hook-aitch ⟨◌ʱ⟩ for the breathy-voiced release of obstruents.

Questions and answers:
['
Q: What do some linguists restrict the double-dot subscript ⟨◌̤⟩ to?
A: murmured sonorants', '
Q: What are, according to the text, murmured for their duration?
A: vowels and nasals', '
Q: What uses the ⟨◌ʱ⟩?
A: breathy-voiced release of obstruents.']
Hydrogen is a chemical element with chemical symbol H and atomic number 1. With an atomic weight of 7000100794000000000♠1.00794 u, hydrogen is the lightest element on the periodic table. Its monatomic form (H) is the most abundant chemical substance in the Universe, constituting roughly 75% of all baryonic mass.[note 1] Non-remnant stars are mainly composed of hydrogen in its plasma state. The most common isotope of hydrogen, termed protium (name rarely used, symbol 1H), has one proton and no neutrons.

Questions and answers:
['
Q: What is hydrogens chemical symbol?
A: H', '
Q: What is the atomic number used for hydrogen?
A: 1', '
Q: What is the atomic weight for hydrogen?
A: 7000100794000000000♠1.00794 u', '
Q: What element is considered the lightest?
A: Hydrogen']
The universal emergence of atomic hydrogen first occurred during the recombination epoch. At standard temperature and pressure, hydrogen is a colorless, odorless, tasteless, non-toxic, nonmetallic, highly combustible diatomic gas with the molecular formula H2. Since hydrogen readily forms covalent compounds with most non-metallic elements, most of the hydrogen on Earth exists in molecular forms such as in the form of water or organic compounds. Hydrogen plays a particularly important role in acid–base reactions as many acid-base reactions involve the exchange of protons between soluble molecules. In ionic compounds, hydrogen can take the form of a negative charge (i.e., anion) when it is known as a hydride, or as a positively charged (i.e., cation) species denoted by the symbol H+. The hydrogen cation is written as though composed of a bare proton, but in reality, hydrogen cations in ionic compounds are always more complex species than that would suggest. As the only neutral atom for which the Schrödinger equation can be solved analytically, study of the energetics and bonding of the hydrogen atom has played a key role in the development of quantum mechanics.

Questions and answers:
['
Q: What form can you find hydrogen is on Earth?
A: molecular', '
Q: What is the molecular make-up of hydrogen?
A: H2', '
Q: What are three properties of hydrogen at normal temperature and normal pressure?
A: colorless, odorless, tasteless', '
Q: What charge does hydrogen display in ionic compounds when it is called a hydride?
A: negative', "
Q: What field of study has hydrogen and it's properties played a key role in development?
A: quantum mechanics"]
Hydrogen gas was first artificially produced in the early 16th century, via the mixing of metals with acids. In 1766–81, Henry Cavendish was the first to recognize that hydrogen gas was a discrete substance, and that it produces water when burned, a property which later gave it its name: in Greek, hydrogen means "water-former".

Questions and answers:
['
Q: When was hydrogen gas artificially produced for the first time?
A: early 16th century', '
Q: Who first recognized that hydrogen was a discrete substance?
A: Henry Cavendish', '
Q: When it is burned what does hydrogen make?
A: water', '
Q: What is the Greek translation for hydrogen?
A: water-former']
Industrial production is mainly from the steam reforming of natural gas, and less often from more energy-intensive hydrogen production methods like the electrolysis of water. Most hydrogen is employed near its production site, with the two largest uses being fossil fuel processing (e.g., hydrocracking) and ammonia production, mostly for the fertilizer market. Hydrogen is a concern in metallurgy as it can embrittle many metals, complicating the design of pipelines and storage tanks.

Questions and answers:
['
Q: What market primarily uses ammonia production?
A: the fertilizer market', '
Q: Name a process that uses fossil fuels along with hydrogen.
A: hydrocracking']
Hydrogen gas (dihydrogen or molecular hydrogen) is highly flammable and will burn in air at a very wide range of concentrations between 4% and 75% by volume. The enthalpy of combustion for hydrogen is −286 kJ/mol:

Questions and answers:
['
Q: For hydrogen what is the enthalpy of combustion?
A: 286 kJ/mol', '
Q: What are two forms of hydrogen gas?
A: dihydrogen or molecular hydrogen', '
Q: Which element has a enthalpy of combustion at −286 kJ/mol?
A: Hydrogen']
Hydrogen gas forms explosive mixtures with air if it is 4–74% concentrated and with chlorine if it is 5–95% concentrated. The mixtures may be ignited by spark, heat or sunlight. The hydrogen autoignition temperature, the temperature of spontaneous ignition in air, is 500 °C (932 °F). Pure hydrogen-oxygen flames emit ultraviolet light and with high oxygen mix are nearly invisible to the naked eye, as illustrated by the faint plume of the Space Shuttle Main Engine compared to the highly visible plume of a Space Shuttle Solid Rocket Booster. The detection of a burning hydrogen leak may require a flame detector; such leaks can be very dangerous. Hydrogen flames in other conditions are blue, resembling blue natural gas flames. The destruction of the Hindenburg airship was an infamous example of hydrogen combustion; the cause is debated, but the visible orange flames were the result of a rich mixture of hydrogen to oxygen combined with carbon compounds from the airship skin.

Questions and answers:
['
Q: What kind of light do hydrogen-oxygen flames make?
A: ultraviolet light', '
Q: What caused  the Hindenburg to explode?
A: hydrogen combustion']
H2 reacts with every oxidizing element. Hydrogen can react spontaneously and violently at room temperature with chlorine and fluorine to form the corresponding hydrogen halides, hydrogen chloride and hydrogen fluoride, which are also potentially dangerous acids.

Questions and answers:
['
Q: What are two other dangerous acids?
A: hydrogen chloride and hydrogen fluoride', '
Q: What temperature does hydrogen react with these elements?
A: room temperature']
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.

Questions and answers:
['
Q: What model id used to calculate energy levels of hydrogen?
A: Bohr model', '
Q: What attracts planets and celestial items?
A: gravity', '
Q: What does the electromagnetic force attract to one another?
A: electrons and protons']