sentence-transformers/squad huggingface dataset:
Passage: Zinc is a bluish-white, lustrous, diamagnetic metal, though most common commercial grades of the metal have a dull finish. It is somewhat less dense than iron and has a hexagonal crystal structure, with a distorted form of hexagonal close packing, in which each atom has six nearest neighbors (at 265.9 pm) in its own plane and six others at a greater distance of 290.6 pm. The metal is hard and brittle at most temperatures but becomes malleable between 100 and 150 °C. Above 210 °C, the metal becomes brittle again and can be pulverized by beating. Zinc is a fair conductor of electricity. For a metal, zinc has relatively low melting (419.5 °C) and boiling points (907 °C). Its melting point is the lowest of all the transition metals aside from mercury and cadmium.

Question: What color is zinc?

Question: Is iron more dense than zinc?

Question: At what temperature does the metal become malleable?

Question: At what temperature to zinc become brittle?

Question: What is the boiling point of zinc?

Question: In it's pre commercial state, what color is zinc?

Question: What is the crystalline structure of sync?

Question: What happens to zinc when it is manipulated to the temperatures between 100 and 150 Celsius?

Question: At what temperature can zinc be pulverized?
Passage: Several dozen radioisotopes have been characterized. 65Zn, which has a half-life of 243.66 days, is the most long-lived radioisotope, followed by 72Zn with a half-life of 46.5 hours. Zinc has 10 nuclear isomers. 69mZn has the longest half-life, 13.76 h. The superscript m indicates a metastable isotope. The nucleus of a metastable isotope is in an excited state and will return to the ground state by emitting a photon in the form of a gamma ray. 61Zn has three excited states and 73Zn has two. The isotopes 65Zn, 71Zn, 77Zn and 78Zn each have only one excited state.

Question: How many radioisotopes of zinc have been discovered?

Question: What is the longest half life of the isotopes?

Question: What does the superscript m represent?

Question: How many excited states does 61Zn have?

Question: How many excited states does 73Zn have?

Question: What is the most long lived radio isotope?

Question: What is the half life of 72Zn?

Question: How many nuclear isomers does zinc have?

Question: What does the superscript "m" indicate?

Question: What does a metastable isotope do to return to ground state from an excited state?
Passage: The chemistry of zinc is dominated by the +2 oxidation state. When compounds in this oxidation state are formed the outer shell s electrons are lost, which yields a bare zinc ion with the electronic configuration [Ar]3d10. In aqueous solution an octahedral complex, [Zn(H 2O)6]2+ is the predominant species. The volatilization of zinc in combination with zinc chloride at temperatures above 285 °C indicates the formation of Zn 2Cl 2, a zinc compound with a +1 oxidation state. No compounds of zinc in oxidation states other than +1 or +2 are known. Calculations indicate that a zinc compound with the oxidation state of +4 is unlikely to exist.

Question: What oxidation state dominates zinc?

Question: What indicates the formation of ZN2Cl?

Question: what are the only two oxidation states known for zinc?

Question: What oxidation state dominates the chemistry of zinc?

Question: What are the only two oxidation states known for zinc compounds?
Passage: Zinc chemistry is similar to the chemistry of the late first-row transition metals nickel and copper, though it has a filled d-shell, so its compounds are diamagnetic and mostly colorless. The ionic radii of zinc and magnesium happen to be nearly identical. Because of this some of their salts have the same crystal structure and in circumstances where ionic radius is a determining factor zinc and magnesium chemistries have much in common. Otherwise there is little similarity. Zinc tends to form bonds with a greater degree of covalency and it forms much more stable complexes with N- and S- donors. Complexes of zinc are mostly 4- or 6- coordinate although 5-coordinate complexes are known.

Question: Because zinc has a filled d-shell, its compounds are usually what?

Question: The ionic radii of what two elements are almost identical?

Question: What is the determining factor where zinc and magnesium are very similar chemically?

Question: Whit what donors does zinc form stable complexes?
Passage: Zinc(I) compounds are rare, and require bulky ligands to stabilize the low oxidation state. Most zinc(I) compounds contain formally the [Zn2]2+ core, which is analogous to the [Hg2]2+ dimeric cation present in mercury(I) compounds. The diamagnetic nature of the ion confirms its dimeric structure. The first zinc(I) compound containing the Zn—Zn bond, (η5-C5Me5)2Zn2, is also the first dimetallocene. The [Zn2]2+ ion rapidly disproportionates into zinc metal and zinc(II), and has only been obtained as a yellow glass formed by cooling a solution of metallic zinc in molten ZnCl2.

Question: What is necessary to stabilize the low oxidation state of zinc(l) compounds?

Question: What core do most zinc(l) compounds contain?

Question: What confirms the dimeric structure of the compound?

Question: When a solution of metallic zinc is cooled in molten ZnCl2, what is formed?
Passage: Binary compounds of zinc are known for most of the metalloids and all the nonmetals except the noble gases. The oxide ZnO is a white powder that is nearly insoluble in neutral aqueous solutions, but is amphoteric, dissolving in both strong basic and acidic solutions. The other chalcogenides (ZnS, ZnSe, and ZnTe) have varied applications in electronics and optics. Pnictogenides (Zn 3N 2, Zn 3P 2, Zn 3As 2 and Zn 3Sb 2), the peroxide (ZnO 2), the hydride (ZnH 2), and the carbide (ZnC 2) are also known. Of the four halides, ZnF 2 has the most ionic character, whereas the others (ZnCl 2, ZnBr 2, and ZnI 2) have relatively low melting points and are considered to have more covalent character.

Question: What is not known for binary compounds of zinc?

Question: ZnO can be dissolved in what kind of solutions?

Question: What applications do chalcogenides have?
Passage: In weak basic solutions containing Zn2+ ions, the hydroxide Zn(OH) 2 forms as a white precipitate. In stronger alkaline solutions, this hydroxide is dissolved to form zincates ([Zn(OH)4]2−). The nitrate Zn(NO3) 2, chlorate Zn(ClO3) 2, sulfate ZnSO 4, phosphate Zn 3(PO4) 2, molybdate ZnMoO 4, cyanide Zn(CN) 2, arsenite Zn(AsO2) 2, arsenate Zn(AsO4) 2·8H 2O and the chromate ZnCrO 4 (one of the few colored zinc compounds) are a few examples of other common inorganic compounds of zinc. One of the simplest examples of an organic compound of zinc is the acetate (Zn(O 2CCH3) 2).

Question: Zn(OH)2 is dissolved to form what in strong alkaline solutions?
Passage: The Charaka Samhita, thought to have been written between 300 and 500 AD, mentions a metal which, when oxidized, produces pushpanjan, thought to be zinc oxide. Zinc mines at Zawar, near Udaipur in India, have been active since the Mauryan period. The smelting of metallic zinc here, however, appears to have begun around the 12th century AD. One estimate is that this location produced an estimated million tonnes of metallic zinc and zinc oxide from the 12th to 16th centuries. Another estimate gives a total production of 60,000 tonnes of metallic zinc over this period. The Rasaratna Samuccaya, written in approximately the 13th century AD, mentions two types of zinc-containing ores: one used for metal extraction and another used for medicinal purposes.

Question: Zinc oxide is believed to be mentioned in what ancient text?

Question: Active zinc mines in India date back to what period?

Question: What process occurred around the 12th century?

Question: When was the Rasaratna Samuccaya written?

Question: What are the two uses of zinc ore mentioned in the Rasaratna Samuccaya?
Passage: The name of the metal was probably first documented by Paracelsus, a Swiss-born German alchemist, who referred to the metal as "zincum" or "zinken" in his book Liber Mineralium II, in the 16th century. The word is probably derived from the German zinke, and supposedly meant "tooth-like, pointed or jagged" (metallic zinc crystals have a needle-like appearance). Zink could also imply "tin-like" because of its relation to German zinn meaning tin. Yet another possibility is that the word is derived from the Persian word سنگ seng meaning stone. The metal was also called Indian tin, tutanego, calamine, and spinter.

Question: Who is attributed as first documenting zinc?

Question: Why is it possible that the name zinc could be derived from the German zinn?

Question: Why would zinc possibly be derived from the German word zinke?

Question: What are some of the other terms for zinc?
Passage: William Champion's brother, John, patented a process in 1758 for calcining zinc sulfide into an oxide usable in the retort process. Prior to this, only calamine could be used to produce zinc. In 1798, Johann Christian Ruberg improved on the smelting process by building the first horizontal retort smelter. Jean-Jacques Daniel Dony built a different kind of horizontal zinc smelter in Belgium, which processed even more zinc. Italian doctor Luigi Galvani discovered in 1780 that connecting the spinal cord of a freshly dissected frog to an iron rail attached by a brass hook caused the frog's leg to twitch. He incorrectly thought he had discovered an ability of nerves and muscles to create electricity and called the effect "animal electricity". The galvanic cell and the process of galvanization were both named for Luigi Galvani and these discoveries paved the way for electrical batteries, galvanization and cathodic protection.

Question: Who first patented the process that creates an oxide usable in the retort process?

Question: Before John Champion, what was the only element used to produce zinc?

Question: Who built the first horizontal retort smelter?

Question: What did Galvani name the effect he created of causing the frogs legs to twitch?

Question: The discoveries made by Galvani lead to what three important things?
Passage: Zinc metal is produced using extractive metallurgy. After grinding the ore, froth flotation, which selectively separates minerals from gangue by taking advantage of differences in their hydrophobicity, is used to get an ore concentrate. This concentrate consists of about 50% zinc with the rest being sulfur (32%), iron (13%), and SiO 2 (5%). The composition of this is normally zinc sulfide (80% to 85%), iron sulfide (7.0% to 12%), lead sulfide (3.0% to 5.0%) silica (2.5% to 3.5%), and cadmium sulfide (0.35% to 0.41%).

Question: What is used to produce the metal zinc?

Question: What is froth flotation used for?

Question: What is the first step in zinc metal production?

Question: What percentage of the ore concentrate is zinc?
Passage: The production for sulfidic zinc ores produces large amounts of sulfur dioxide and cadmium vapor. Smelter slag and other residues of process also contain significant amounts of heavy metals. About 1.1 million tonnes of metallic zinc and 130 thousand tonnes of lead were mined and smelted in the Belgian towns of La Calamine and Plombières between 1806 and 1882. The dumps of the past mining operations leach significant amounts of zinc and cadmium, and, as a result, the sediments of the Geul River contain significant amounts of heavy metals. About two thousand years ago emissions of zinc from mining and smelting totaled 10 thousand tonnes a year. After increasing 10-fold from 1850, zinc emissions peaked at 3.4 million tonnes per year in the 1980s and declined to 2.7 million tonnes in the 1990s, although a 2005 study of the Arctic troposphere found that the concentrations there did not reflect the decline. Anthropogenic and natural emissions occur at a ratio of 20 to 1.

Question: Large amounts of sulfur dioxide and cadmium vapor are produced due to what?

Question: Smelter slag contains a significant amount of what?

Question: Why does the Geul River contain heavy metals in a significant amount?

Question: What is the ratio that anthropogenic and natural emissions occur at?
Passage: Zinc is more reactive than iron or steel and thus will attract almost all local oxidation until it completely corrodes away. A protective surface layer of oxide and carbonate (Zn 5(OH) 6(CO 3) 2) forms as the zinc corrodes. This protection lasts even after the zinc layer is scratched but degrades through time as the zinc corrodes away. The zinc is applied electrochemically or as molten zinc by hot-dip galvanizing or spraying. Galvanization is used on chain-link fencing, guard rails, suspension bridges, lightposts, metal roofs, heat exchangers, and car bodies.

Question: What two compounds is zinc more reactive than?

Question: What forms as zinc corrodes?

Question: How is zinc applied?

Question: What is used on many common items, such as chain link fences?
Passage: The relative reactivity of zinc and its ability to attract oxidation to itself makes it an efficient sacrificial anode in cathodic protection (CP). For example, cathodic protection of a buried pipeline can be achieved by connecting anodes made from zinc to the pipe. Zinc acts as the anode (negative terminus) by slowly corroding away as it passes electric current to the steel pipeline.[note 2] Zinc is also used to cathodically protect metals that are exposed to sea water from corrosion. A zinc disc attached to a ship's iron rudder will slowly corrode, whereas the rudder stays unattacked. Other similar uses include a plug of zinc attached to a propeller or the metal protective guard for the keel of the ship.

Question: What makes zinc an efficient sacrificial anode?

Question: Connecting anodes made from zinc to buried pipe creates what?

Question: What does attaching a zinc disc to a ships iron rudder do?

Question: Why does zinc protect metals exposed to sea water from corroding?
Passage: Other widely used alloys that contain zinc include nickel silver, typewriter metal, soft and aluminium solder, and commercial bronze. Zinc is also used in contemporary pipe organs as a substitute for the traditional lead/tin alloy in pipes. Alloys of 85–88% zinc, 4–10% copper, and 2–8% aluminium find limited use in certain types of machine bearings. Zinc is the primary metal used in making American one cent coins since 1982. The zinc core is coated with a thin layer of copper to give the impression of a copper coin. In 1994, 33,200 tonnes (36,600 short tons) of zinc were used to produce 13.6 billion pennies in the United States.

Question: What has zinc replaced in pipe organs?

Question: Zinc, copper and aluminum alloys have use in what part of machinery?

Question: Zinc in the main metal used in making which american currency?

Question: What is zinc coated with to influence the look of pennies?
Passage: Alloys of primarily zinc with small amounts of copper, aluminium, and magnesium are useful in die casting as well as spin casting, especially in the automotive, electrical, and hardware industries. These alloys are marketed under the name Zamak. An example of this is zinc aluminium. The low melting point together with the low viscosity of the alloy makes the production of small and intricate shapes possible. The low working temperature leads to rapid cooling of the cast products and therefore fast assembly is possible. Another alloy, marketed under the brand name Prestal, contains 78% zinc and 22% aluminium and is reported to be nearly as strong as steel but as malleable as plastic. This superplasticity of the alloy allows it to be molded using die casts made of ceramics and cement.

Question: Aside from die casting, what are alloys of zinc mixed with copper, aluminium and magnesium used for?

Question: Alloys of zinc mixed with copper, aluminium and magnesium are marketed as what?

Question: What is possible to produce thanks to the low melting point and low viscosity of zinc aluminium alloy?

Question: What brand name of alloy is supposed to be as strong as steel while still being malleable as plastic?

Question: What is used to mold Prestal?
Passage: Similar alloys with the addition of a small amount of lead can be cold-rolled into sheets. An alloy of 96% zinc and 4% aluminium is used to make stamping dies for low production run applications for which ferrous metal dies would be too expensive. In building facades, roofs or other applications in which zinc is used as sheet metal and for methods such as deep drawing, roll forming or bending, zinc alloys with titanium and copper are used. Unalloyed zinc is too brittle for these kinds of manufacturing processes.

Question: What can be done when small amounts of lead are added to alloys?

Question: What is made with an alloy of 4% aluminium mixed with 96% zinc?

Question: Why are alloys used to make stamping dies rather than metal?

Question: Why isn't unalloyed zinc used in construction applications?
Passage: Roughly one quarter of all zinc output in the United States (2009), is consumed in the form of zinc compounds; a variety of which are used industrially. Zinc oxide is widely used as a white pigment in paints, and as a catalyst in the manufacture of rubber. It is also used as a heat disperser for the rubber and acts to protect its polymers from ultraviolet radiation (the same UV protection is conferred to plastics containing zinc oxide). The semiconductor properties of zinc oxide make it useful in varistors and photocopying products. The zinc zinc-oxide cycle is a two step thermochemical process based on zinc and zinc oxide for hydrogen production.

Question: In what form is 1/4 of zinc used in the US?

Question: What kind of zinc compound is used in manufacturing rubber?

Question: What protects the polymers in rubber from ultraviolet radiation?

Question: Why is zinc oxide useful in photocopying products?

Question: What kind of process is the zinc zinc-oxide cycle?
Passage: Zinc chloride is often added to lumber as a fire retardant and can be used as a wood preservative. It is also used to make other chemicals. Zinc methyl (Zn(CH3) 2) is used in a number of organic syntheses. Zinc sulfide (ZnS) is used in luminescent pigments such as on the hands of clocks, X-ray and television screens, and luminous paints. Crystals of ZnS are used in lasers that operate in the mid-infrared part of the spectrum. Zinc sulfate is a chemical in dyes and pigments. Zinc pyrithione is used in antifouling paints.

Question: What is added to wood in order to preserve it?

Question: What is the feature of zinc sufide that makes it useful in television screens?

Question: What kind of lasers are crystals of zinc suflde used in?

Question: Where is zinc pyrithion used?
Passage: 64Zn, the most abundant isotope of zinc, is very susceptible to neutron activation, being transmuted into the highly radioactive 65Zn, which has a half-life of 244 days and produces intense gamma radiation. Because of this, Zinc Oxide used in nuclear reactors as an anti-corrosion agent is depleted of 64Zn before use, this is called depleted zinc oxide. For the same reason, zinc has been proposed as a salting material for nuclear weapons (cobalt is another, better-known salting material). A jacket of isotopically enriched 64Zn would be irradiated by the intense high-energy neutron flux from an exploding thermonuclear weapon, forming a large amount of 65Zn significantly increasing the radioactivity of the weapon's fallout. Such a weapon is not known to have ever been built, tested, or used. 65Zn is also used as a tracer to study how alloys that contain zinc wear out, or the path and the role of zinc in organisms.

Question: What is the most abundant zinc isotope?

Question: What does 65Zn produce?

Question: Why is zinc oxide used in nuclear reactors?

Question: What is used to study how alloys containing zinc wear out?
Passage: Zinc is included in most single tablet over-the-counter daily vitamin and mineral supplements. Preparations include zinc oxide, zinc acetate, and zinc gluconate. It is believed to possess antioxidant properties, which may protect against accelerated aging of the skin and muscles of the body; studies differ as to its effectiveness. Zinc also helps speed up the healing process after an injury. It is also suspected of being beneficial to the body's immune system. Indeed, zinc deficiency may have effects on virtually all parts of the human immune system.

Question: What consumable product is zinc included in?

Question: What property of zinc is believed to protect against skin aging?

Question: What is the benefit of zinc after injury?
Passage: Although not yet tested as a therapy in humans, a growing body of evidence indicates that zinc may preferentially kill prostate cancer cells. Because zinc naturally homes to the prostate and because the prostate is accessible with relatively non-invasive procedures, its potential as a chemotherapeutic agent in this type of cancer has shown promise. However, other studies have demonstrated that chronic use of zinc supplements in excess of the recommended dosage may actually increase the chance of developing prostate cancer, also likely due to the natural buildup of this heavy metal in the prostate.

Question: What kind of cancer cells may zinc prove to kill?

Question: What type of agent is zync useful as against prostate cancer?

Question: What could overuse of zinc possibly cause?

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

Question: What does organozinc chemisty describe?

Question: What is the zinc equivalent of the Grinard reaction?

Question: When will organomagnesium halide formation fail?

Question: What are dimethylzinc, dietylzinc and diphenylzinc?
Passage: Zinc serves a purely structural role in zinc fingers, twists and clusters. Zinc fingers form parts of some transcription factors, which are proteins that recognize DNA base sequences during the replication and transcription of DNA. Each of the nine or ten Zn2+ ions in a zinc finger helps maintain the finger's structure by coordinately binding to four amino acids in the transcription factor. The transcription factor wraps around the DNA helix and uses its fingers to accurately bind to the DNA sequence.

Question: What role does zinc play in fingers, twists and clusters?

Question: What are proteins that druing replication and transcription of DNA, recognize base DNA?

Question: How many amino acids do the Zn2+ ions bind to?

Question: What does the transcription factor wrap around?