romikgosai/squad_modified huggingface dataset:
Brass, which is an alloy of copper and zinc, has been used since at least the 10th century BC in Judea and by the 7th century BC in Ancient Greece. Zinc metal was not produced on a large scale until the 12th century in India and was unknown to Europe until the end of the 16th century. The mines of Rajasthan have given definite evidence of zinc production going back to the 6th century BC. To date, the oldest evidence of pure zinc comes from Zawar, in Rajasthan, as early as the 9th century AD when a distillation process was employed to make pure zinc. Alchemists burned zinc in air to form what they called "philosopher's wool" or "white snow".

Questions and answers:
['
Q: What two metals are mixed to create Brass?
A: copper and zinc', '
Q: When was brass first used?
A: 10th', '
Q: Where was zinc first produced on a large scale?
A: India', '
Q: When was zinc introduced to Europe?
A: end of the 16th century', '
Q: Where is the oldest evidence of pure zinc?
A: Zawar', '
Q: Brass is an alloy of what two elements?
A: copper and zinc', '
Q: The earliest uses of brass has been attributed to what ancient location?
A: Judea', '
Q: We have evidence of zinc production dating back to the 6th century thanks to what mine?
A: Rajasthan', '
Q: What early process was used to make zinc?
A: distillation process', '
Q: What were the names given to zinc by early alchemists?
A: "philosopher\'s wool" or "white snow"']
The element was probably named by the alchemist Paracelsus after the German word Zinke (prong, tooth). German chemist Andreas Sigismund Marggraf is credited with discovering pure metallic zinc in 1746. Work by Luigi Galvani and Alessandro Volta uncovered the electrochemical properties of zinc by 1800. Corrosion-resistant zinc plating of iron (hot-dip galvanizing) is the major application for zinc. Other applications are in batteries, small non-structural castings, and alloys, such as brass. A variety of zinc compounds are commonly used, such as zinc carbonate and zinc gluconate (as dietary supplements), zinc chloride (in deodorants), zinc pyrithione (anti-dandruff shampoos), zinc sulfide (in luminescent paints), and zinc methyl or zinc diethyl in the organic laboratory.

Questions and answers:
['
Q: Who named the element zinc?
A: Paracelsus', '
Q: What was zinc named after?
A: Zinke', '
Q: Who is credited with discovering zinc?
A: Andreas Sigismund Marggraf', '
Q: What two people discovered the electrochemical properties of zinc?
A: Luigi Galvani and Alessandro Volta', '
Q: Where can you find zinc chloride?
A: deodorants', '
Q: Who is credited as giving zinc its name?
A: Paracelsus', '
Q: What does the name zinc or zinke mean?
A: (prong, tooth)', '
Q: Who discovered pure metallic zinc?
A: Andreas Sigismund Marggraf', '
Q: What is the most common use for zinc?
A: (hot-dip galvanizing', '
Q: What is a common use for zinc chloride?
A: deodorants']
Zinc is an essential mineral perceived by the public today as being of "exceptional biologic and public health importance", especially regarding prenatal and postnatal development. Zinc deficiency affects about two billion people in the developing world and is associated with many diseases. In children it causes growth retardation, delayed sexual maturation, infection susceptibility, and diarrhea. Enzymes with a zinc atom in the reactive center are widespread in biochemistry, such as alcohol dehydrogenase in humans. Consumption of excess zinc can cause ataxia, lethargy and copper deficiency.

Questions and answers:
['
Q: How many people are affected by zinc deficiency?
A: two billion', '
Q: What can consumption of excess zinc cause?
A: ataxia, lethargy and copper deficiency', '
Q: Where can you find enzymes with a zinc atom in the reactive center?
A: biochemistry,', '
Q: What can a lack of zinc cause in children?
A: growth retardation, delayed sexual maturation, infection susceptibility, and diarrhea', '
Q: What is extremely important to prenatal and postnatal development?
A: Zinc', '
Q: What can cause symptoms in children ranging from diarrhea to retarded growth?
A: Zinc deficiency', '
Q: In what substance can you find a zinc atom within its reactive center?
A: alcohol dehydrogenase', '
Q: What causes symptoms such as lethargy and copper deficiency?
A: excess zinc']
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.

Questions and answers:
['
Q: What color is zinc?
A: bluish-white', '
Q: Is iron more dense than zinc?
A: It is somewhat less dense than iron', '
Q: At what temperature does the metal become malleable?
A: 100 and 150 °C', '
Q: At what temperature to zinc become brittle?
A: 210 °C', '
Q: What is the boiling point of zinc?
A: 907 °C', "
Q: In it's pre commercial state, what color is zinc?
A: bluish-white", '
Q: What is the crystalline structure of sync?
A: hexagonal', '
Q: What happens to zinc when it is manipulated to the temperatures between 100 and 150 Celsius?
A: becomes malleable', '
Q: At what temperature can zinc be pulverized?
A: 210 °C']
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.

Questions and answers:
['
Q: How many radioisotopes of zinc have been discovered?
A: Several dozen', '
Q: What is the longest half life of the isotopes?
A: 243.66', '
Q: What does the superscript m represent?
A: metastable isotope', '
Q: How many excited states does 61Zn have? 
A: three', '
Q: How many excited states does 73Zn have?
A: two', '
Q: What is the most long lived radio isotope?
A: 65Zn', '
Q: What is the half life of 72Zn?
A: 46.5 hours', '
Q: How many nuclear isomers does zinc have?
A: 10', '
Q: What does the superscript "m" indicate?
A: metastable isotope', '
Q: What does a metastable isotope do to return to ground state from an excited state?
A: emitting a photon in the form of a gamma ray']
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.

Questions and answers:
['
Q: What oxidation state dominates zinc?
A: +2', '
Q: What indicates the formation of ZN2Cl?
A: The volatilization of zinc in combination with zinc chloride at temperatures above 285 °C', '
Q: what are the only two oxidation states known for zinc?
A: +1 or +2', '
Q: What oxidation state dominates the chemistry of zinc?
A: +2', '
Q: What are the only two oxidation states known for zinc compounds?
A: +1 or +2']
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.

Questions and answers:
['
Q: Because zinc has a filled d-shell, its compounds are usually what?
A: diamagnetic and mostly colorless.', '
Q: The ionic radii of what two elements are almost identical?
A: zinc and magnesium', '
Q: What is the determining factor where zinc and magnesium are very similar chemically?
A: ionic radius', '
Q: Whit what donors does zinc form stable complexes?
A: N- and S-']
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.

Questions and answers:
['
Q: What is necessary to stabilize the low oxidation state of zinc(l) compounds?
A: bulky ligands', '
Q: What core do most zinc(l) compounds contain?
A: [Zn2]2+', '
Q: What confirms the dimeric structure of the compound?
A: diamagnetic nature of the ion', '
Q: When a solution of metallic zinc is cooled in molten ZnCl2, what is formed?
A: yellow glass']
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.

Questions and answers:
['
Q: What is not known for binary compounds of zinc?
A: noble gases', '
Q: ZnO can be dissolved in what kind of solutions?
A: strong basic and acidic solutions', '
Q: What applications do chalcogenides have?
A: electronics and optics.']
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).

Questions and answers:
['
Q: Zn(OH)2 is dissolved to form what in strong alkaline solutions?
A: zincates']
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.

Questions and answers:
['
Q: Zinc oxide is believed to be mentioned in what ancient text?
A: The Charaka Samhita', '
Q: Active zinc mines in India date back to what period?
A: Mauryan period', '
Q: What process occurred around the 12th century?
A: smelting of metallic zinc', '
Q: When was the Rasaratna Samuccaya written?
A: 13th century AD,', '
Q: What are the two uses of zinc ore mentioned in the Rasaratna Samuccaya?
A: metal extraction and another used for medicinal purposes']
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.

Questions and answers:
['
Q: Who is attributed as first documenting zinc?
A: Paracelsus', '
Q: Why is it possible that the name zinc could be derived from the German zinn?
A: imply "tin-like"', '
Q: Why would zinc possibly be derived from the German word zinke?
A: metallic zinc crystals have a needle-like appearance', '
Q: What are some of the other terms for zinc?
A: Indian tin, tutanego, calamine, and spinter.']
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.

Questions and answers:
["
Q: Who first patented the process that creates an oxide usable in the retort process?
A: William Champion's brother, John,", '
Q: Before John Champion, what was the only element used to produce zinc?
A: calamine', '
Q: Who built the first horizontal retort smelter?
A: Johann Christian Ruberg', '
Q: What did Galvani name the effect he created of causing the frogs legs to twitch?
A: animal electricity', '
Q: The discoveries made by Galvani lead to what three important things?
A: electrical batteries, galvanization and cathodic protection.']
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%).

Questions and answers:
['
Q: What is used to produce the metal zinc?
A: extractive metallurgy.', '
Q: What is froth flotation used for?
A: get an ore concentrate', '
Q: What is the first step in zinc metal production?
A: grinding the ore', '
Q: What percentage of the ore concentrate is zinc?
A: 50%']
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.

Questions and answers:
['
Q: Large amounts of sulfur dioxide and cadmium vapor are produced due to what?
A: The production for sulfidic zinc ores', '
Q: Smelter slag contains a significant amount of what?
A: heavy metals', '
Q: Why does the Geul River contain heavy metals in a significant amount?
A: mining operations leach significant amounts of zinc and cadmium', '
Q: What is the ratio that anthropogenic and natural emissions occur at?
A: 20 to 1']
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.

Questions and answers:
['
Q: What two compounds is zinc more reactive than?
A: iron or steel', '
Q: What forms as zinc corrodes?
A: protective surface layer of oxide and carbonate', '
Q: How is zinc applied?
A: electrochemically or as molten zinc', '
Q: What is used on many common items, such as chain link fences?
A: Galvanization']
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.

Questions and answers:
['
Q: What makes zinc an efficient sacrificial anode?
A: relative reactivity of zinc and its ability to attract oxidation', '
Q: Connecting anodes made from zinc to buried pipe creates what?
A: cathodic protection', '
Q: What does attaching a zinc disc to a ships iron rudder do?
A: protect metals that are exposed to sea water from corrosion', '
Q: Why does zinc protect metals exposed to sea water from corroding?
A: will slowly corrode, whereas the rudder stays unattacked']
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.

Questions and answers:
['
Q: What has zinc replaced in pipe organs?
A: lead/tin alloy', '
Q: Zinc, copper and aluminum alloys have use in what part of machinery?
A: machine bearings', '
Q: Zinc in the main metal used in making which american currency?
A: one cent coins', '
Q: What is zinc coated with to influence the look of pennies?
A: thin layer of copper']
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.

Questions and answers:
['
Q: Aside from die casting, what are alloys of zinc mixed with copper, aluminium and magnesium used for?
A: spin casting', '
Q: Alloys of zinc mixed with copper, aluminium and magnesium are marketed as what?
A: Zamak', '
Q: What is possible to produce thanks to the low melting point and low viscosity of zinc aluminium alloy?
A: small and intricate shapes', '
Q: What brand name of alloy is supposed to be as strong as steel while still being malleable as plastic?
A: Prestal', '
Q: What is used to mold Prestal?
A: die casts made of ceramics and cement.']
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.

Questions and answers:
['
Q: What can be done when small amounts of lead are added to alloys?
A: cold-rolled into sheets', '
Q: What is made with an alloy of 4% aluminium mixed with 96% zinc?
A: stamping dies', '
Q: Why are alloys used to make stamping dies rather than metal?
A: too expensive', "
Q: Why isn't unalloyed zinc used in construction applications?
A: too brittle"]
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.

Questions and answers:
['
Q: In what form is 1/4 of zinc used in the US?
A: zinc compounds', '
Q: What kind of zinc compound is used in manufacturing rubber?
A: Zinc oxide', '
Q: What protects the polymers in rubber from ultraviolet radiation?
A: Zinc oxide', '
Q: Why is zinc oxide useful in photocopying products?
A: semiconductor', '
Q: What kind of process is the zinc zinc-oxide cycle?
A: thermochemical']