praj-17/QA-MCQ-Open-ended huggingface dataset:
Title: Vacuum
Context: The SI unit of pressure is the pascal (symbol Pa), but vacuum is often measured in torrs, named for Torricelli, an early Italian physicist (1608–1647). A torr is equal to the displacement of a millimeter of mercury (mmHg) in a manometer with 1 torr equaling 133.3223684 pascals above absolute zero pressure. Vacuum is often also measured on the barometric scale or as a percentage of atmospheric pressure in bars or atmospheres. Low vacuum is often measured in millimeters of mercury (mmHg) or pascals (Pa) below standard atmospheric pressure. "Below atmospheric" means that the absolute pressure is equal to the current atmospheric pressure.

question: Absolute pressure  being equal to current atmospheric pressure means what? 

answer: "Below atmospheric"

question: What is a torr equal to? 

answer: displacement of a millimeter of mercury

question: What is another often used options to measure vacuum? 

answer: barometric scale
Title: Vacuum
Context: Hydrostatic gauges (such as the mercury column manometer) consist of a vertical column of liquid in a tube whose ends are exposed to different pressures. The column will rise or fall until its weight is in equilibrium with the pressure differential between the two ends of the tube. The simplest design is a closed-end U-shaped tube, one side of which is connected to the region of interest. Any fluid can be used, but mercury is preferred for its high density and low vapour pressure. Simple hydrostatic gauges can measure pressures ranging from 1 torr (100 Pa) to above atmospheric. An important variation is the McLeod gauge which isolates a known volume of vacuum and compresses it to multiply the height variation of the liquid column. The McLeod gauge can measure vacuums as high as 10−6 torr (0.1 mPa), which is the lowest direct measurement of pressure that is possible with current technology. Other vacuum gauges can measure lower pressures, but only indirectly by measurement of other pressure-controlled properties. These indirect measurements must be calibrated via a direct measurement, most commonly a McLeod gauge.

question: Why is mercury the better option for liquid used in a Hydrostatic gauge? 

answer: its high density and low vapour pressure

question: What is a vertical column of liquid in a tube which has different pressures at each end called? 

answer: Hydrostatic gauges

question: What is a hydrostatic gauge used for? 

answer: measure pressures ranging from 1 torr (100 Pa) to above atmospheric

question: Why is the McLeod gauge special? 

answer: can measure vacuums as high as 10−6 torr

question: An indirect measurement of pressure is most often calibrated by what? 

answer: McLeod gauge
Title: Vacuum
Context: Thermal conductivity gauges rely on the fact that the ability of a gas to conduct heat decreases with pressure. In this type of gauge, a wire filament is heated by running current through it. A thermocouple or Resistance Temperature Detector (RTD) can then be used to measure the temperature of the filament. This temperature is dependent on the rate at which the filament loses heat to the surrounding gas, and therefore on the thermal conductivity. A common variant is the Pirani gauge which uses a single platinum filament as both the heated element and RTD. These gauges are accurate from 10 torr to 10−3 torr, but they are sensitive to the chemical composition of the gases being measured.

question: The fact that gases ability to conduct heat decreases with pressure is used by what form of measurement? 

answer: Thermal conductivity gauges

question: How is the wire filament in a Thermal conductivity gauge heated? 

answer: by running current through it

question: What is a Pirani gauge sensitive to? 

answer: chemical composition of the gases being measured

question: What is a RTD used for on a Thermal Conductivity gauge? 

answer: to measure the temperature of the filament

question: A Pirani gauge is accurate within what ranges? 

answer: 10 torr to 10−3 torr
Title: Vacuum
Context: Ion gauges are used in ultrahigh vacuum. They come in two types: hot cathode and cold cathode. In the hot cathode version an electrically heated filament produces an electron beam. The electrons travel through the gauge and ionize gas molecules around them. The resulting ions are collected at a negative electrode. The current depends on the number of ions, which depends on the pressure in the gauge. Hot cathode gauges are accurate from 10−3 torr to 10−10 torr. The principle behind cold cathode version is the same, except that electrons are produced in a discharge created by a high voltage electrical discharge. Cold cathode gauges are accurate from 10−2 torr to 10−9 torr. Ionization gauge calibration is very sensitive to construction geometry, chemical composition of gases being measured, corrosion and surface deposits. Their calibration can be invalidated by activation at atmospheric pressure or low vacuum. The composition of gases at high vacuums will usually be unpredictable, so a mass spectrometer must be used in conjunction with the ionization gauge for accurate measurement.

question: What affects the number of ions in a gauge? 

answer: the pressure in the gauge

question: What must be used for accurate measurement on the composition of gases at a high vacuums? 

answer: mass spectrometer must be used in conjunction with the ionization gauge

question: What gauge is accurate from 10-2 torr to 10-9 torr? 

answer: Cold cathode gauges

question: Why does a mass spectrometer need to be used with gauge to be accurate at high vacuum gas measurement? 

answer: composition of gases at high vacuums will usually be unpredictable

question: What are the two types of Ion gauges? 

answer: hot cathode and cold cathode.
Title: Vacuum
Context: Cold or oxygen-rich atmospheres can sustain life at pressures much lower than atmospheric, as long as the density of oxygen is similar to that of standard sea-level atmosphere. The colder air temperatures found at altitudes of up to 3 km generally compensate for the lower pressures there. Above this altitude, oxygen enrichment is necessary to prevent altitude sickness in humans that did not undergo prior acclimatization, and spacesuits are necessary to prevent ebullism above 19 km. Most spacesuits use only 20 kPa (150 Torr) of pure oxygen. This pressure is high enough to prevent ebullism, but decompression sickness and gas embolisms can still occur if decompression rates are not managed.

question: density of oxygen like that of sea-level atmosphere is needed to do what? 

answer: sustain life at pressures much lower than atmospheric,

question: What is the lowest altitude where acclimatization or a suit is not needed to prevent sickness in humans? 

answer: of up to 3 km
Title: Vacuum
Context: Humans and animals exposed to vacuum will lose consciousness after a few seconds and die of hypoxia within minutes, but the symptoms are not nearly as graphic as commonly depicted in media and popular culture. The reduction in pressure lowers the temperature at which blood and other body fluids boil, but the elastic pressure of blood vessels ensures that this boiling point remains above the internal body temperature of 37 °C. Although the blood will not boil, the formation of gas bubbles in bodily fluids at reduced pressures, known as ebullism, is still a concern. The gas may bloat the body to twice its normal size and slow circulation, but tissues are elastic and porous enough to prevent rupture. Swelling and ebullism can be restrained by containment in a flight suit. Shuttle astronauts wore a fitted elastic garment called the Crew Altitude Protection Suit (CAPS) which prevents ebullism at pressures as low as 2 kPa (15 Torr). Rapid boiling will cool the skin and create frost, particularly in the mouth, but this is not a significant hazard.

question: When will a person or animal lose consciousness  when exposed to a vacuum? 

answer: after a few seconds

question: A shuttle astronauts prevents ebullism at 2 kPa with what item? 

answer: the Crew Altitude Protection Suit (CAPS)

question: What is the forming of gas bubbles in body fluids at a lowered pressure called? 

answer: ebullism

question: What prevents body rupture at low altitude when human body is bloated by gas bubbles? 

answer: tissues are elastic and porous
Title: Vacuum
Context: In ultra high vacuum systems, some very "odd" leakage paths and outgassing sources must be considered. The water absorption of aluminium and palladium becomes an unacceptable source of outgassing, and even the adsorptivity of hard metals such as stainless steel or titanium must be considered. Some oils and greases will boil off in extreme vacuums. The permeability of the metallic chamber walls may have to be considered, and the grain direction of the metallic flanges should be parallel to the flange face.

question: What can boil away in extreme vaccum exposure? 

answer: Some oils and greases

question: How should the grain direct of metallic flanges run to flange faces? 

answer: parallel

question: What are 2 metals that can be absorbed in an ultra high vacuum system? 

answer: stainless steel or titanium

question: What becomes a concern in an ultra high vacuum system regarding aluminum or palladium? 

answer: water absorption
Title: Vacuum
Context: In quantum mechanics and quantum field theory, the vacuum is defined as the state (that is, the solution to the equations of the theory) with the lowest possible energy (the ground state of the Hilbert space). In quantum electrodynamics this vacuum is referred to as 'QED vacuum' to distinguish it from the vacuum of quantum chromodynamics, denoted as QCD vacuum. QED vacuum is a state with no matter particles (hence the name), and also no photons. As described above, this state is impossible to achieve experimentally. (Even if every matter particle could somehow be removed from a volume, it would be impossible to eliminate all the blackbody photons.) Nonetheless, it provides a good model for realizable vacuum, and agrees with a number of experimental observations as described next.

question: The state with the lowest possible energy in quantum mechanics defines what ? 

answer: vacuum

question: A vacuum state with no matter particles or photons is called what? 

answer: QED

question: why is a QED vacuum impossible to achieve ? 

answer: impossible to eliminate all the blackbody photons

question: What is a QCD? 

answer: vacuum of quantum chromodynamics,
Title: Vacuum
Context: QED vacuum has interesting and complex properties. In QED vacuum, the electric and magnetic fields have zero average values, but their variances are not zero. As a result, QED vacuum contains vacuum fluctuations (virtual particles that hop into and out of existence), and a finite energy called vacuum energy. Vacuum fluctuations are an essential and ubiquitous part of quantum field theory. Some experimentally verified effects of vacuum fluctuations include spontaneous emission and the Lamb shift. Coulomb's law and the electric potential in vacuum near an electric charge are modified.

question: When are electric and magnetic fields with zero average values, but their variances are not at zero? 

answer: In QED vacuum

question: What is a verified effect of vacuum fluctuation? 

answer: spontaneous emission

question: what is  vacuum fluctuation? 

answer: virtual particles that hop into and out of existence

question: Finite energy in a QED is called what? 

answer: vacuum energy

question: What modifies can Coulomb's Law in a vacuum? 

answer: vacuum near an electric charge
Title: Vacuum
Context: Stars, planets, and moons keep their atmospheres by gravitational attraction, and as such, atmospheres have no clearly delineated boundary: the density of atmospheric gas simply decreases with distance from the object. The Earth's atmospheric pressure drops to about 6998320000000000000♠3.2×10−2 Pa at 100 kilometres (62 mi) of altitude, the Kármán line, which is a common definition of the boundary with outer space. Beyond this line, isotropic gas pressure rapidly becomes insignificant when compared to radiation pressure from the Sun and the dynamic pressure of the solar winds, so the definition of pressure becomes difficult to interpret. The thermosphere in this range has large gradients of pressure, temperature and composition, and varies greatly due to space weather. Astrophysicists prefer to use number density to describe these environments, in units of particles per cubic centimetre.

question: `Why does thermosphere past the Karman line vary so greatly? 

answer: due to space weather

question: What is commonly known as the boundary of outer space? 

answer: the Kármán line

question: What do Astrophysicists use to describe outer space beyond the karman line? 

answer: number density

question: What is more significant than isotropic gas pressure past the Karman line? 

answer: radiation pressure from the Sun and the dynamic pressure of the solar winds
Title: Vacuum
Context: Vacuum is useful in a variety of processes and devices. Its first widespread use was in the incandescent light bulb to protect the filament from chemical degradation. The chemical inertness produced by a vacuum is also useful for electron beam welding, cold welding, vacuum packing and vacuum frying. Ultra-high vacuum is used in the study of atomically clean substrates, as only a very good vacuum preserves atomic-scale clean surfaces for a reasonably long time (on the order of minutes to days). High to ultra-high vacuum removes the obstruction of air, allowing particle beams to deposit or remove materials without contamination. This is the principle behind chemical vapor deposition, physical vapor deposition, and dry etching which are essential to the fabrication of semiconductors and optical coatings, and to surface science. The reduction of convection provides the thermal insulation of thermos bottles. Deep vacuum lowers the boiling point of liquids and promotes low temperature outgassing which is used in freeze drying, adhesive preparation, distillation, metallurgy, and process purging. The electrical properties of vacuum make electron microscopes and vacuum tubes possible, including cathode ray tubes. The elimination of air friction is useful for flywheel energy storage and ultracentrifuges.

question: What was the object to use first in widespread manner process of vacuum? 

answer: incandescent light bulb

question: What is produced by a vacuum and used in electron beam welding and vacuum frying? 

answer: chemical inertness

question: Hight to ultra-high vacuums removes what obstruction? 

answer: obstruction of air,

question: How does freeze drying, distillation and metallurgy benefit from a deep vacuum? 

answer: Deep vacuum lowers the boiling point of liquids and promotes low temperature outgassing

question: What are two things made possible by the electrical properties of vacuum? 

answer: electron microscopes and vacuum tubes
Title: Vacuum
Context: Manifold vacuum can be used to drive accessories on automobiles. The best-known application is the vacuum servo, used to provide power assistance for the brakes. Obsolete applications include vacuum-driven windscreen wipers and Autovac fuel pumps. Some aircraft instruments (Attitude Indicator (AI) and the Heading Indicator (HI)) are typically vacuum-powered, as protection against loss of all (electrically powered) instruments, since early aircraft often did not have electrical systems, and since there are two readily available sources of vacuum on a moving aircraft—the engine and an external venturi. Vacuum induction melting uses electromagnetic induction within a vacuum.

question: What provides power assistance for auto brakes? 

answer: vacuum servo

question: What are two available sources of vacuum on a moving airplane? 

answer: engine and an external venturi

question: Why are the Attitude indicator and heading indicator vacuum-powered? 

answer: protection against loss of all (electrically powered) instruments,

question: What does a manifold vacuum do on a car? 

answer: drive accessories

question: What no longer used accessories were powered by vacuum? 

answer: vacuum-driven windscreen wipers and Autovac fuel pumps
Title: Vacuum
Context: Evaporation and sublimation into a vacuum is called outgassing. All materials, solid or liquid, have a small vapour pressure, and their outgassing becomes important when the vacuum pressure falls below this vapour pressure. In man-made systems, outgassing has the same effect as a leak and can limit the achievable vacuum. Outgassing products may condense on nearby colder surfaces, which can be troublesome if they obscure optical instruments or react with other materials. This is of great concern to space missions, where an obscured telescope or solar cell can ruin an expensive mission.

question: what is evaporation and sublimation in a vacuum? 

answer: outgassing

question: Why can outgassing products ruin a space mission? 

answer: obscure optical instruments

question: When does outgassing become important in all solid or liquid materials? 

answer: vacuum pressure falls below this vapour pressure
Title: Vacuum
Context: To continue evacuating a chamber indefinitely without requiring infinite growth, a compartment of the vacuum can be repeatedly closed off, exhausted, and expanded again. This is the principle behind positive displacement pumps, like the manual water pump for example. Inside the pump, a mechanism expands a small sealed cavity to create a vacuum. Because of the pressure differential, some fluid from the chamber (or the well, in our example) is pushed into the pump's small cavity. The pump's cavity is then sealed from the chamber, opened to the atmosphere, and squeezed back to a minute size.

question: Repeatedly closing off a compartment of a vacuum allows what? 

answer: continue evacuating a chamber indefinitely without requiring infinite growth

question: How is a vacuum created inside of a manual water pump? 

answer: a mechanism expands a small sealed cavity

question: Why is fluid in a manual pump pushed into the pumps cavity when a small sealed cavity is expanded? 

answer: Because of the pressure differential

question: What are pumps based off principle of sealed compartment pulling,pushing and expanding called? 

answer: displacement pumps
Title: Vacuum
Context: The above explanation is merely a simple introduction to vacuum pumping, and is not representative of the entire range of pumps in use. Many variations of the positive displacement pump have been developed, and many other pump designs rely on fundamentally different principles. Momentum transfer pumps, which bear some similarities to dynamic pumps used at higher pressures, can achieve much higher quality vacuums than positive displacement pumps. Entrapment pumps can capture gases in a solid or absorbed state, often with no moving parts, no seals and no vibration. None of these pumps are universal; each type has important performance limitations. They all share a difficulty in pumping low molecular weight gases, especially hydrogen, helium, and neon.

question: What pump can capture gases in a solid or absorbed state? 

answer: Entrapment pumps

question: Entrapment pumps often work without seals, moving parts and what else? 

answer: no vibration.

question: What pump has a higher quality vacuum than a positive displacement pump? 

answer: Momentum transfer pumps
Title: Vacuum
Context: The lowest pressure that can be attained in a system is also dependent on many things other than the nature of the pumps. Multiple pumps may be connected in series, called stages, to achieve higher vacuums. The choice of seals, chamber geometry, materials, and pump-down procedures will all have an impact. Collectively, these are called vacuum technique. And sometimes, the final pressure is not the only relevant characteristic. Pumping systems differ in oil contamination, vibration, preferential pumping of certain gases, pump-down speeds, intermittent duty cycle, reliability, or tolerance to high leakage rates.

question: When multiple pumps are connected in series to produce higher vacuum it is called what? 

answer: stages

question: The choice of seals, or chamber geometry ,for example impact a pump. Together these are options are called what? 

answer: vacuum technique

question: What are two other relevant characteristics of a pumping system along with final pressure? 

answer: oil contamination, vibration
Title: Han_dynasty
Context: The Han dynasty (Chinese: 漢朝; pinyin: Hàn cháo) was the second imperial dynasty of China, preceded by the Qin dynasty (221–207 BC) and succeeded by the Three Kingdoms period (220–280 AD). Spanning over four centuries, the Han period is considered a golden age in Chinese history. To this day, China's majority ethnic group refers to itself as the "Han people" and the Chinese script is referred to as "Han characters". It was founded by the rebel leader Liu Bang, known posthumously as Emperor Gaozu of Han, and briefly interrupted by the Xin dynasty (9–23 AD) of the former regent Wang Mang. This interregnum separates the Han dynasty into two periods: the Western Han or Former Han (206 BC – 9 AD) and the Eastern Han or Later Han (25–220 AD).

question: What period followed the Han dynasty? 

answer: Three Kingdoms

question: What dynasty came before the Han dynasty? 

answer: Qin

question: Who founded the Han dynasty? 

answer: Liu Bang

question: When did the Former Han period begin? 

answer: 206 BC

question: When did the Later Han period end? 

answer: 220 AD
Title: Han_dynasty
Context: The emperor was at the pinnacle of Han society. He presided over the Han government but shared power with both the nobility and appointed ministers who came largely from the scholarly gentry class. The Han Empire was divided into areas directly controlled by the central government using an innovation inherited from the Qin known as commanderies, and a number of semi-autonomous kingdoms. These kingdoms gradually lost all vestiges of their independence, particularly following the Rebellion of the Seven States. From the reign of Emperor Wu onward, the Chinese court officially sponsored Confucianism in education and court politics, synthesized with the cosmology of later scholars such as Dong Zhongshu. This policy endured until the fall of the Qing dynasty in AD 1911.

question: When did the Qing dynasty fall? 

answer: AD 1911

question: What innovation was acquired from the Qin? 

answer: commanderies

question: What philosphy in education was sanctioned by the Chinese court? 

answer: Confucianism

question: What was an attributing factor that caused kingdoms to lose their Independence during the Han dynasty? 

answer: the Rebellion of the Seven States

question: What class did a majority of appointed ministers come from during the Han dynasty? 

answer: scholarly gentry
Title: Han_dynasty
Context: The Han dynasty was an age of economic prosperity and saw a significant growth of the money economy first established during the Zhou dynasty (c. 1050–256 BC). The coinage issued by the central government mint in 119 BC remained the standard coinage of China until the Tang dynasty (618–907 AD). The period saw a number of limited institutional innovations. To pay for its military campaigns and the settlement of newly conquered frontier territories, the government nationalized the private salt and iron industries in 117 BC, but these government monopolies were repealed during the Eastern Han period. Science and technology during the Han period saw significant advances, including papermaking, the nautical steering rudder, the use of negative numbers in mathematics, the raised-relief map, the hydraulic-powered armillary sphere for astronomy, and a seismometer employing an inverted pendulum.

question: In what year did the central government issue coins? 

answer: 119 BC

question: What industry did the government use to help pay for its military campaigns? 

answer: iron

question: In what period did several government monopolies become repealed? 

answer: Eastern Han

question: A money based economy was first entrenched in what dynasty? 

answer: Zhou

question: A seismometer during the Han dynasty used what type of pendulum? 

answer: inverted