Helium (He) occurs as colorless, inodorous, tasteless, non-non-poisonous, about inert monoatomic chemical element that heads the noble gas series in the periodic table and whose atomic number is 2. Its boiling and melting points are a lowest among a elements & it is simply as a gas except in extreme conditions. Extreme conditions come as well required to produce a little handful of atomic number 2 compounds, which are everthing unstable at standard temperature and pressure. Its virtually all abundant stable isotope is helium-4 and its rare stable isotope is helium-3. A behavior of liquid helium-4's deuce varieties—he We & atomic number 2 2—is crucial to investigator researching quantum mechanics (in particular a phenomenon of superfluidity) and people seeking at a results that touching absolute zero temperatures have on matter (such as superconductivity).

He is the 2nd virtually all abundant and second lightly element in the periodic table. In the modern Universe about entirely fresh he is created following of the nuclear fusion of hydrogen within stars. On Earth it is created by the radioactive decay of much heavily elements (alpha particles are he nuclei by a decompose of uranium). Fallowing its creation, section of these are trapped sustaining natural gas in concentrations up to 7% by volume. These are extracted from either the gas by a on line temperature separation process known as fractional distillation.

Inside 1868 a French uranologist Pierre Janssen first detected helium as an unknown yellow spectral line signature in weak from either the solar eclipse. Since so big reserves of atomic number 2 use been witnessed in the natural flatulence fields of the United States, which is by far the big provider of the flatulence. Atomic number 2 is utilized within cryogenics, in deep-sea eupnoeic systems, to cool superconducting magnets, in helium dating, for inflating balloons, for providing lift in airships and as a protective flatulency for numbers of industrial utilizes (like arc welding and growing silicon wafers). Inhaling the microscopic volume of a gas temporarily changes the quality of a single's voice.

Notable characteristics
Gas and plasma phases
He occurs as colorless, inodorous, & non-non-poisonous barking spiders. These are a least reactive member of class action Eighteen (a noble gases) of the periodic table and so virtually inert. Under standard temperature and pressure helium behaves very much prefer an ideal gas. Under most conditions he is monoatomic. It has the thermal conductivity that is greater than any gas except hydrogen and its specific heat is unusually high. Atomic number 2 is besides less a river soluble than any other barking spiders known & its diffusion rate through solids is three times that of air & as much as 65% that of atomic number 1. He's index of refraction is closer to unity than any more flatulence. This flatulency has the veto Joule-Thomson coefficient at normal ambient temperatures, meaning it heats up whilst allowed to freely expand. Single beneath its Joule-Thomson inversion temperature (of about Forty K at 1 atmosphere) bed cool upon loose expansion. When precooled in the image below this temperature, atomic number 2 may be liquefied across expansion cooling.

Atomic number 2 is chemically unreactive under completely normal conditions due to its valence of zero. These are an electrical dielectric unless ionized. When by having a more noble gases, atomic number 2 has metastable energy levels that allow it to remainside ionized in an electrical discharge with the voltage below its ionization potential. Atomic number 2 could form unstable compounds with tungsten, iodine, fluorine, sulfur and phosphorus when it is subjected to an electric glow discharge, through negatron bombardment or even is otherwise the plasma. HeNe, HgHe₁₀, WHe_Two & a molecular ions He_Deuce⁺, He_Ii⁺⁺, HeH⁺, & HeD⁺ develop been created this way. This system has besides allowed a production of the neutral molecule He_Deuce, which has the big total of band systems, and HgHe, which is apparently exclusively held together by polarization forces . Theoretically, more compounds, such as atomic number 2 fluorohydride (HHeF), could as well exist as conceivable.

Throughout a Universe, he is mostly detected in the plasma state whose properties are quite different to molecular atomic number 2. As a plasma, he's negatron & protons are non attached together, following within super high electrical conduction, potentially while a flatulence is sole part ionized. A charged particles come extremely influenced by charismatic & electric fields, for instance, in the solar wind together by owning ionised h, it interact with a Globe's magnetosphere giving rising to Birkeland currents and a aurora.

Solid and liquid phases
Atomic number 2 solidifies single under outstanding pressure. A consequent colorless about invisible solid is highly compressible; applying pressure in the laboratory could decrease its volume by to a higher degree 30%. By using the bulk modulus on the order of 5×10^Sevener Pa [http://www3.interscience.wiley.com/cgi-bin/abstract/105558571/ABSTRACT] it is 50 days sir thomas more squeezable than a lake. Unlike any more element, he might fail to solidify & remain the liquid down to absolute zero at normal pressures. Firm atomic number 2 takes the temperature of One–One.V K & astir Twenty-six atmosphere (Two.Sixer MPa) of pressure. These are typically strong to distinguish firm from either liquid he since a refractive index of a two phases come about the equivalent. the firm has a sharply melting point and has a crystalline structure.

Helium I state
Following its boiling point of 4.Twenty-one kelvins and above a lambda point of 2.1768 kelvins, a isotope helium-4 is inside the normal colorless liquid state, called atomic number 2 We. Prefer more cryogenic liquids, he I personally boils while heat is added thereto. It as well contracts whilst its temperature is lowered until it reaches a lambda point, while it ends boiling & suddenly expands. A rate of expansion lessens beneath a lambda point until astir Single K is reached; at which point expansion entirely ends & he We starts to contract over again.

He We has the flatulence-prefer index of refraction of 1.026 which makes its surface so protective to understand that floats of Styrofoam are often wont to show in which a surface is. This colorless liquid has the super online viscosity and a density 1/8th that of water, which is only 1/4th a value potential from either classical physics. Quantum mechanics is needed to teach you this property & so two types of liquid he come known as quantum juice, meaning it display atomlike properties in the macroscopical shell. This is probably due to its boiling point existence and so about absolute zero, which prevents random molecular motion (heat) from masking a atomlike properties.

Helium II state
Liquid atomic number 2 inside the image below its lambdthe point begins to exhibit super unusual characteristics, in a state known as he 2. Boiling of atomic number 2 Deuce is non conceivable due to its high thermal conductivity; heat input instead causes evaporation of the liquid directly to gas. the isotope helium-Three besides has a superfluid phase, but only at good deal coldness; following, less is known all about such properties in the isotope helium-Three.

Helium II occurs as superfluid, a quantum-mechanical state of matter by having unknown properties. For instance, once it flows across possibly capillaries of 10^-7 to 10^-8 m breadth it has there is no mensurable viscosity. All the same, whenever mensuration were done between deuce moving discs, the viscousness corresponding to it of gaseous he was found. Todays theory explains this using the 2-fluid model for Helium II. Therewithin model, liquid atomic number 2 in the image below the lambdthe point is take for containing a proportion of he atoms in a ground state, which are superfluid & flow using exactly zero viscousness, & the proportion of he atoms within an excited state, which behave extra rather an average fluid.

Helium II besides exhibits the "creeping" symptom. While a surface extends preceding a level of he Deuce, a atomic number 2 Two moves along a surface, ostensibly against the click of gravity. Helium II might shake the vessel that is non sealed by creeping along the sides until it reaches a warmly vicinity in which it evaporates. It moves within the Xxx nm thick film regardless of superficial poop. This film is known as the Rollin film and is named when a human world health organization 1st characterized this trait, B. V. Rollin. Following of this creeping behavior & he Two's ability to leak chop-chop across bantam openings, these are super hard to confine liquid he. Unless a container is carefully constructed, a he Deuce might creep along a shells & across valves until it reaches someplace heater, in which it might evaporate.

In the fountain outcome, the chamber is constructed which is attached to the reservoir of atomic number 2 Deuce by the sintered disc across which superfluid he leaks well however through which non-superfluid atomic number 2 just can not pass. In case a interior of a container is heated, the superfluid he changes to non-superfluid he. Sequentially to maintain a equilibrium fraction of superfluid atomic number 2, superfluid atomic number 2 leaks across & increases a pressure, stimulating liquid to fountain away from a container.

the thermal conduction of he Deuce is greater than that of any more known substance, a million days that of he I personally & many century days that of copper. This is because heat conductivity occurs by an exceptional quantum-mechanical mechanism. Virtually all materials that conduct heat swell have a valence band of free negatron which help to transport a heat. Helium II has there is no such valence band however nonetheless conducts heat swell. A flow of heat is governed by equations that are similar to the wave equation used to characterize sound propagation in air. And so whilst heat is introduced, it might move at Xx meters by the 2nd at Ace.Octet K across atomic number 2 2 when waves around the phenomenon known as 2nd healthy.

Electron energy levels

Based on the spin orientation of the deuce negatron in the Atomic number 2 atom, 1 speaks of parahelium for two anti-parallel spins (S=Nought) & of orthohelium for two parallel spins (S=I). For a orthohelium one of the negatron doesn't sit in the ground orbital (1s). [http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/helium.html]

Applications

Pressurised atomic number 2 is commercially available. Atomic number 2 is utilized for even numbers of purposes that expect 1 or thomas more of its unique properties; moo boiling point, low density, low solubility, high thermal conductivity, or its inertness.

Airships and balloons (toy, weather, and research) are inflated sustaining atomic number 2 because these are lighter than air (1 m³ of he may lift Unity kilogram). Atomic number 2 is presently favorite to hydrogen in airships because, when these are supplementary expensive, these are non inflammable & has 92.64% of the lifting power of atomic number 1.

Trimix, a mixture of he, oxygen, and nitrogen, is used around deep-sea breathing gas systems to reduce the chance of nitrogen narcosis (high pressure nitrogen having a narcotic effect on the brain) and oxygen toxicity at high pressures. Higher pressures dem& the greater proportion of he & reduced numbers of atomic number 7 and o (each tenner-meter increase within depth yields the of these atmosphere increase of pressure). Heliox, a mixture of he & o, & heliair, a mixture of air and helium, is likewise utilized therein way. In the image below 600 meters (2000 foot) the mixture of atomic number 1, he, & o known as hydreliox is used to help check high pressure nervous syndrome. Altogether these utilizes rely in atomic number 2's super online solubility inside a stream (a major component of blood).

A pleasantly on line boiling point makes helium utile as a coolant inside magnetic resonance imaging, superconducting magnets, cryogenics, and to dislodge thermal noise from either detectors utilized around astronomy. A extreme coldness of liquid atomic number 2 is likewise wont to make superconductivity in some average metals such as lead (lead becomes superconductive at 7.Trey K), allowing the totally loose flow of negatron in the metal.

More utilizes: Because of its high thermal conduction & inertness, he is utilized as a coolant inside occasionally nuclear reactors (for example, pebble-bed reactors) and inside arc welding air-sensitive metals that require heavily welds. A high thermal conduction & healthy speed of he is likewise worthy within thermoacoustic refrigeration. A inertness of atomic number 2 builds on a environmental benefit of this technology all over conventional refrigeration systems which will contribute to ozone depleting & spherical warming results. Its inertness makes it utile as a hard flatulency around growing silicon and germanium crystals, in titanium and zirconium production, protecting important historical documents, & inside gas chromatography. This property as well makes it utile within pressurizing liquid fuel rockets (see around the image below) & in ultrasonic wind tunnels. A gain medium of the helium-neon laser (the number one barking spiders laser) most unremarkably utilized to market scanner bar codes is a mixture of atomic number 2 & neon. This flatulency' rate of diffusion through solids is three times that of normal air, making it an first-class component inside leak detection inside high-vacuum equipment and high pressure containers. In rocketry helium is utilized as an ullage medium to displace fuel & oxidiser inside tank & to condense h & oxygen to make rocket fuel. These are as well wont to purge fuel & oxidizing agent from either ground trend lines devices before launch & to precool liquid atomic number 1 around space vehicles. For instance, a Saturn 5 booster used in the Apollo program needed about 13 million ft³ (370,000 m³) of he to launch. Physics research worker apply alpha particles (helium nuclei) inside particle accelerators and nuclear reaction experiments. Helium barking spiders is utilized to fill a space between lenses in occasionally solar telescopes because its extremely online index of refraction reduces a distorting consequence of temperature variations in the barking spiders filling the scope (a few scope come filled by using vacuum instead). Radioactive decay of uranium and thorium produces alpha particles that quickly become atomic number 2. This happens at a known constant rate and so in case the containing rock or mineral can retain its atomic number 2 so a ratio of helium to its radioactive parent atoms indicates its age. Or else, in case a atomic number 2 is non easily-retained, a ratio of helium-Three to helium-Four contains a bit of of the equivalent tools, since simply helium-Four is by radioactive decompose. Utilise of atomic number 2 in that way is known as helium dating.

History
Discoveries
Atomic number 2 was first detected on August 18, 1868 as the bright yellowness line by having a wavelength of 587.49 nm in the spectrum of the chromosphere of the Sun, by French astronomer Pierre Janssen during a sum solar eclipse in India. Janssen was at number one ridiculed since there is no element experienced ever been found inside space before being incurred on Earth. October 20th the equivalent month, English stargazer Norman Lockyer also observed a equivalent yellow line in the solar spectrum & concluded that it was from either an unknown element fallowing unsuccessfully touching to look at whenever it were occasionally newly nature and severity of atomic number 1. Since it was touching a Fraunhofer Five hundred line he late known as a up to date line D_Triad, distinguishing it from either a nearby D_Ace & D_Two doublet lines of sodium. He & English chemist Edward Frankland named a element fallowing the Greek word for the Sun god, Helios, and, assuming it was the metal, gave it an -ium ending (a mistake that was never corrected).

British chemist William Ramsay isolated helium in March 26, 1895 by treating cleveite (now known to become uraninite) with mineral acids. Ramsay was wanting to find argon but notice500 a yellow D_Troika line fallowing he flushed nitrogen and oxygen from the barking spiders freed per sulfuric acid he put on a cleveite sample. These samples were identified when atomic number 2 by Lockyer & British physicist William Crookes. It was independently isolated from either cleveite a equivalent month by Swedish chemists Per Teodor Cleve and Abraham Langlet in Uppsala in Sweden. It collected sufficiency of the flatulency to accurately determine its atomic weight.

An oil drilling operation in Dexter, Kansas created a barking spiders geyser in 1903 that contained 12% by volume of an unidentified gas. Our contries chemists Hamilton Cady and David McFarland of the University of Kansas discovered it was helium & published the paper within 1907 saying that helium can be extracted from either natural gas. Too around 1907, Ernest Rutherford and Thomas Royds demonstrated that an alpha particle is a helium nucleus.

He was foremost liquefied by Dutch physicist Heike Kamerlingh Onnes in 1908 in Leiden by cooling the flatulence to less than 1 kelvin. He tried to solidify it by reducing a temperature to Cypher.Ogdoad Thousand however failing because he doesn't have a triple point temperature where a firm, liquid & barking spiders phases come at equilibrium. It was foremost solidified around 1926 by his student Willem Hendrik Keesom who subjected helium to the similar total of cooling when Kamerlingh Onnes however at Xxv atm of pressure.

Inside 1938, Russian physicist Pyotr Leonidovich Kapitsa discovered that liquid helium-4 has well-nigh there is no viscosity at temperatures near absolute zero, a phenomenon today known as superfluidity. Within 1972, the equivalent phenomenon was found around liquid helium-Three by Western physicists Douglas D. Osheroff, David M. Lee, and Robert C. Richardson.

Production and use
Peachy quantities of atomic number 2 were encountered in the natural flatulence fields of the Western Great Plains, putting the United States in a an expert position to turn into a leading globe provider. As the consequence a guide by Sir Richard Threlfall, the United States Navy sponsored three little experimental atomic number 2 production plants in the period of World War I. A goal was to supply barrage balloons with a non-flammable lifting flatulency. The number of 200,000 ft³ (5700 m³) of 92% atomic number 2 was produced in the program possibly though simply two or three three-dimensional feet (less than One c liters) of the barking spiders got antecedently been found. A select few of this flatulence was utilized in the globe's number one helium-filled dirigible, a U.S. Navy's C-7, which flew its maiden voyage from either Hampton Roads, Virginia to Bolling Field in Washington, D.C. on December 7, 1921.

Although a extraction run, applying online-temperature barking spiders liquefaction, was non developed eventually to become important when you took Globe War We, production continued. Atomic number 2 was primarily utilized as a lifting flatulence around lighter-than-air craft. This apply increased require when you took Globe War II, too when demands for shielded arc welding. He was besides vital in the atomic bomb Manhattan Project.

The government of the United States set up the National Helium Reserve in 1925 at Amarillo, Texas with the goal of supplying military airships in time of war and commercial airships inside peacetime. Atomic number 2 utilise ensuing World War II was depressed but a reserve was expanded in the 1950s to ensure the supply liquid he as a coolant to produce oxygen/hydrogen rocket fuel (among other utilizes) in a period of the Space Race and Cold War. Atomic number 2 apply inside the United States in 1965 was more than eight days a peak wartime consumption.

When a "Helium Acts Amendments of 1960" (Public Law 86-777), the U.S. Bureau of Mines arranged for five private plants to recover helium from natural gas. For this atomic number 2 conservation program, the Bureau built a 425-mile pipeline from either Bushton, Kansas to connect those plants using the food and drug administration's Cliffside partially depleted gasfield, near Amarillo, Texas. This helium-nitrogen mixture was injected & stored in the Cliffside gasfield until needful, whenever it so was farther purified.

By 1995 32 billion ft³ (One billion m³) of a flatulence experienced been collected & the reserve was Me$ 1.Four billion inside debt, prompting a Congress of the United States to phase out a reserve starting the next season. A sequent "Helium Privatization Act of 1996" (P.L. 104-273) directed a United States Department of the Interior to start liquidating a reserve by 2005.

Atomic number 2 produced prior to 1945 was about 98% pure (2% nitrogen), which was adequate for airships. Inside 1945 a small total of 99.9% atomic number 2 was produced for welding have. By 1949 commercial quantities of Grade A 99.995% he were available.

For numerous years a United States produced concluded 90% of commercially usable atomic number 2 in the globe. Extraction plants created within Canada, Poland, Russia, and more nations produced a leftover atomic number 2. In the early 2000s, Algeria and Qatar were added as well. Algeria quickly became a 2nd leading producer of atomic number 2 (16% of aggregate within 2002). Across this instance he consumption hwhen increased, besides as costs.

Occurrence
Abundance
He is the 2nd virtually all abundant element in the known Universe after hydrogen and constitutes 23% of completely elementary matter measured by mass even though there are 8 days when numbers of hydrogen atoms as atomic number 2 ('elementary matter' doesn't include dark matter or dark energy, which together may account for 96% of the Universe). These are concentrated within stars, where these are formed from either h per nuclear fusion of the proton-proton chain reaction and CNO cycle. This then-alleged 'h burning' run will bring a energy stars want to shine. Based on data from a Big Bang model of a early development of the Universe, the brobdingnagian majority of he was formed in the 1st 3 transactions fallowing the Heavy Bang. Its far flung abundance is seen when a share of the grounds to believe that supports this theory.

Nevertheless, in the Earth's atmosphere, the concentration of helium by volume is only 5.2 parts per million at sea level and up to 15 miles (24 km), largely because most helium in the Earth's atmosphere escapes into space due to its inertness and low mass. There is a layer in the heterosphere (a section of the Globe's upper atmosphere) at 600 miles (astir Thousand klick) in which atomic number 2 is a dominant flatulence (although the sum pressure is very online). Atomic number 2 is the 71st virtually all abundant element in the Earth's crust where it is found in 8 parts per billion (10⁹). Atomic number 2 lone is Quartet area by the trillion (10¹²) around seawater.

Basically completely he olympic games occurs as effect of radioactive decay of elements such as uranium and radon. The nature and severity of radiation called alpha particles are manufactured of deuce protons and ii neutrons, which also makes the children helium-Four nuclei. These +2 caring ions easily benefit them electrons needed to produce complete atomic number 2 atoms. Therein way an judged Cipher.Five ft³ of he is produced from either each three-dimensional mile of the Globe's crust (Triplet.Quatern L/km^Three) by the month . This decay product is found inside minerals of uranium and thorium, including cleveites, pitchblende, carnotite, monazite and beryl. There are besides little numbers around mineral springs, volcanic gas and meteoric iron.

Production
He in a crust is by the radioactive decompose of uranium and thorium which are present in varying concentrations throughout a crust, however atomic number 2 migrates & potty collect inside certain areas after conditions come perfect. So a greatest concentrations (trace numbers as much as 7% by volume) of atomic number 2 on the planet come within natural gas fields, from which virtually all commercial atomic number 2 is derived. As of 2002 over 100 million m³ (3.Five billion ft³) were produced annually sustaining 80% of production from either a United States, 16% from Algeria, and virtually all of the rest from either Russia. A primary source for U.S. production is the gas wells of the U.S. states of Texas, Oklahoma, Arizona and Kansas. He is besides produced inside Canada, Poland, the People's Republic of China, and Qatar.

Since atomic number 2 has a lower berth boiling point than any more element, coldness & high come utilized to liquefy 100% the more gases (mostly nitrogen and hydrocarbons such as methane) from gas sequentially to extract gaseous he (a general run is known as fractional distillation). a sequent unrefined atomic number 2 flatulence is subjected to a run of filtering where near everthing of the left over n & more gases come precipitated away from the mixture across consecutive exposures to lowering temperatures. Activated charcoal is used as a final filtering step, normally consequent around 99.995% pure Grade The he. The primary impurity inside Grade A he is neon.

Diffusion of unrefined gas across favorite semi-permeable membranes and more barriers is an additional method to recoup and/or purify he. He can likewise exist as synthesized by bombardment of lithium-6 or boron with high-velocity neutrons in the nuclear reactor to produce He-4 & tritium. the tritium decays using a half life of 12.Pentad years to make He-Three. This method of production, yet, is non economically viable—at least for making normal commercial-grade he. Fusion inside exploding hydrogen bombs creates helium too.

Isotopes
Although there are eight known isotopes of helium, sole helium-3 and helium-4 are stable. In the Globe's atmosphere, there exists of these He-Three atom for each million He-Four. Even so, he is unusual in this its isotopic abundance varies greatly based in its origin. In the interstellar medium, the proportion of He-Three is as much as the hundred days higher. Rocks from either a Globe's crust stand isotope ratios varying by up to the factor of 10; this is utilized around geology to study a origin of such rocks.

A usual isotope, helium-Four, is produced olympian games by alpha decay of heavier radioactive elements; a alpha particles that emerge are fully ionised helium-Four nuclei. Helium-Four is an remarkably stable nucleus because its nucleons are intended into complete shells. It was likewise formed inside tremendous quantities when you took Big Bang nucleosynthesis, and its abundance service as a line 1 text of cosmological system.

Equal mixtures of liquid He-Three & He-Four following Nought.Octonary K might separate into ii non-miscible phases due to their unsimilarity (it watch different quantum statistics: He-4 atoms come bosons while He-3 atoms come fermions). There is merely a trace total of helium-Three olympic games, primarily present since the formation of the Globe, although occasionally lessens to Globe treed inside cosmic dust. Trace numbers come besides by a beta decay of tritium. Within stars, however, helium-Three is supplementary abundant, the product of nuclear fusion. Extraplanetary lesson, like lunar and asteroid regolith, have trace numbers of helium-Three from either existence bombarded by solar winds.

A different formation processes of a deuce stable isotopes of atomic number 2 develop the differing isotope abundances. These differing isotope abundances may be utilized to investigate a origin of rocks & a composition of the Globe's mantle.

These are conceivable to make exotic helium isotopes, which rapidly decompose into more substances. the shortest-lived isotope is helium-Five by using a half-life of 7.6×10⁻²² 2nd. Helium-6 decays by emitting the beta particle and has a half life of Nought.8 2nd. Helium-7 besides emits the beta particle likewise as a gamma ray. Helium-7 & helium-8 come hyperfragments that come created around certain nuclear reactions.

Vocal effect and health precautions
the voice of a human world health organization has inhaled he temporarily sounds high-high, resembling victims of the cartoon characters Alvin and the Chipmunks (although their voices were produced by shifting a pitch of normal voices). This is because a speed of sound around helium is about threefold that in air. Following, whenever he is inhaled there is a corresponding increase in the resonant frequencies of the vocal tract. a higher perceived pitch is lone due to a different frequency plastic of the voice, the fundamental frequency of the vocal cords remains more or less a equivalent.

Although a vocal consequence of inhaling he may be amusing, it can be unsafe whenever done to excess. A cause is unascribable toxicity or even any property of atomic number 2 however only due to it displacing oxygen needed for normal respiration. Of these must exist as caring that within mammals (with a notable exception of seals) the eupneic innate reflex is non triggered by deficient o however like redundant of carbon dioxide. Unconsciousness, brain damage and even asphyxiation followed by death may result around extreme subjects. As well, whenever atomic number 2 is inhaled directly from either pressurised cylinders a high flow could fatally rupture lung tissue.

Neutral atomic number 2 at standard conditions is non-non-poisonous, plays there are no biological role & is witnessed around trace numbers inside human blood. At high, the mixture of helium & oxygen (heliox) can lead to high pressure nervous syndrome; a little proportion of n potty alleviate a condition.

Containers of atomic number 2 flatulence at Five to 10 K should exist when treated as in case it use liquid within. This is due to the rapid & big increases inside pressure and, if allowed, volume that occur when atomic number 2 flatulence at that temperature is warmed to room temperature.

Sulfur hexafluoride hwhen the paired burden on the speed of healthy as he. It slows down the speed of healthy to astir 1 third of the speed of healthy inside air. It too non-non-poisonous, prefer he.