Chemical formula for galena

Chemical formula for galena

Bihar Board. Class 9; Class 10; Class 11; Class 12; CBSE Board Chemical Formula: PbS (Lead Sulfide) Molecular Weight: 239.27 g/mol Crystal System: Cubic Hardness: 2.5 on the Mohs scale, which means it is relatively soft and can be easily scratched. Color: Galena is typically bluish-gray to silver in color but can tarnish to a dull gray.Word Equation. Galena + Dioxygen = Lead (Ii) Oxide + Sulfur Dioxide. PbS + O2 = PbO + SO2 is a Double Displacement (Metathesis) reaction where two moles of Galena [PbS] and three moles of Dioxygen [O 2] react to form two moles of Lead (Ii) Oxide [PbO] and two moles of Sulfur Dioxide [SO 2] Show Chemical Structure Image.Galena is the primary ore mineral of lead. Worked for its lead content as early as 3000 BC, it is found in ore veins with sphalerite, pyrite, chalcopyrite, tennantite-tetrahedrite, etc. and in skarns, as well as in sedimentary rocks where it may replace carbonate beds or be deposited in pore spaces. The crystals are bright when fresh but often ...... equation. This, equation reflects the fact that the reaction rate depends on the ... Solov'ev, “Equilibrium of chemical reactions of oxides of nitrogen with ...Nov 15, 2022 · ratio. of atoms. The formula of a compound shows how many atoms of each element are bonded together. The formula is made up of symbols and numbers. The numbers are written as subscript, which ...Lead (II) sulfide. Molecular Formula PbS. Average mass 239.265 Da. Monoisotopic mass 239.948669 Da. ChemSpider ID 14135. Galena is a lead sulfide mineral with the chemical formula PbS. It consists of lead (Pb) and sulfur (S) atoms arranged in a cubic crystal lattice structure. Unlike minerals with magnetic properties, such as magnetite (Fe3O4), galena lacks the necessary combination of elements and atomic arrangement to exhibit magnetism.Galena is a lead sulfide mineral with a chemical composition of PbS. It is the world's primary ore of lead and is mined from a large number of deposits in many countries. It is found in igneous and metamorphic rocks in medium- to low-temperature hydrothermal veins. In sedimentary rocks … See moreWith the help of Chemical formulas, you can check the number of atoms and elements in the compound. ... Galena. Lead (II) Sulphide. PbS. Galena is mined for its silver content and it is a primary ore of lead. Glauber’s Salt. Sodium Sulphate Decahydrate. Na 2 SO 4.10H 2 O. It is used for medicinal purposes for the removal of certain drugs ...With the help of Chemical formulas, you can check the number of atoms and elements in the compound. ... Galena. Lead (II) Sulphide. PbS. Galena is mined for its silver content and it is a primary ore of lead. Glauber’s Salt. Sodium Sulphate Decahydrate. Na 2 SO 4.10H 2 O. It is used for medicinal purposes for the removal of certain drugs ...Lead(II) oxide, also called lead monoxide, is the inorganic compound with the molecular formula Pb O.PbO occurs in two polymorphs: litharge having a tetragonal crystal structure, and massicot having an orthorhombic crystal structure.Modern applications for PbO are mostly in lead-based industrial glass and industrial ceramics, including computer …General Galena Information : Chemical Formula: PbS : Composition: Molecular Weight = 239.27 gm Lead 86.60 % Pb Sulfur 13.40 % S _____ 100.00 % : Empirical Formula: PbS …Oct 18, 2023 · Halite (/ ˈ h æ l aɪ t, ˈ h eɪ l aɪ t /), commonly known as rock salt, is a type of salt, the mineral (natural) form of sodium chloride (Na Cl).Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, pink, red, orange, yellow or gray depending on inclusion of other materials, impurities, and …Sphalerite and galena occur in very minor amounts, particularly in Cu-rich footwall mineral zones and as late, cross-cutting veins in association with late shear zones and faults (Table 4.3). Sphalerite and galena also occur as interstitial grains in massive sulfide and adjacent to silicate inclusions. Wood does not have a chemical formula because it is not an individual chemical compound but is made up of many chemical structures. Within its cellular structure, there are three chemical components which are principally composed of carbon,...Chemical Formula: PbS Locality: Joplin district of Missouri, Kansas, and Oklahoma and other world wide occurrences. Name Origin: The Roman naturalist, Pliny, used the name galena to describe lead ore. Galena, also called lead glance, is the natural mineral form of lead(II) sulfide. It is the most important ore of lead and an important source of ...Galena - Mindat.org - Mines, Minerals and More Find step-by-step Chemistry solutions and your answer to the following textbook question: Write chemical formulas for galena.Galena, naturally occurring mineral, approximately 1-2in, Thermo Scientific Chemicals ... Molecular Formula, PbS. Molecular Weight (g/mol), 239.26. MDL Number ...Galena is a lead sulfide mineral with the chemical formula PbS. It consists of lead (Pb) and sulfur (S) atoms arranged in a cubic crystal lattice structure. Unlike minerals with magnetic properties, such as magnetite (Fe3O4), galena lacks the necessary combination of elements and atomic arrangement to exhibit magnetism. The IMA symbol is Gn. RRUFF Project. Lead sulfide is a sulfide of lead that occurs naturally as the mineral galena. It is used as a semiconductor and infrared detector. Lead is a heavy metal and stable element with the symbol Pb and the atomic number 82, existing in metallic, organic, and inorganic forms. Sugar: Common table sugar, or sucrose, is a hydrate. Its chemical formula is C12H22O11·H2O, indicating the presence of one water molecule per sucrose molecule. This water molecule contributes to the crystalline structure of sugar. Honey: Honey is a natural sweetener that contains water molecules as hydrates.Bihar Board. Class 9; Class 10; Class 11; Class 12; CBSE BoardFree essays, homework help, flashcards, research papers, book reports, term papers, history, science, politicsApr 28, 2022 · Galena is a mixture, not a compound and so it does not have a chemical formula. It is a mixture of sulphides of lead, silver, arsenic, antimony and copper. It is …Lead (II) sulfide. Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). ?) Lead (II) sulfide (also spelled sulphide) is an inorganic compound with the formula Pb S. Galena is the principal ore and the most important compound of lead. Vanadinite. Vanadinite is a mineral belonging to the apatite group of phosphates, with the chemical formula Pb 5 ( V O 4) 3 Cl. It is one of the main industrial ores of the metal vanadium and a minor source of lead. A dense, brittle mineral, it is usually found in the form of red hexagonal crystals. It is an uncommon mineral, formed by the ...The most common sulfide crystalling in this manner is galena (PbS), the ore mineral of lead. A type of packing that involves two sulfide ions in each of the octahedral positions in the sodium chloride structure is the pyrite structure. This is a high-symmetry structure characteristic of the iron sulfide, pyrite (FeS 2 O). The most common sulfide crystalling in this manner is galena (PbS), the ore mineral of lead. A type of packing that involves two sulfide ions in each of the octahedral positions in the sodium chloride structure is the pyrite structure. This is a high-symmetry structure characteristic of the iron sulfide, pyrite (FeS 2 O). Galena is a gray, cubic, shiny, dense mineral most commonly associated with lead. It is one of the earliest minerals used by humans, and one of the most abundant sulfide minerals on the Earth. Relation to Mining. Galena is still mined today in large quantities, not only for lead, but also for silver. Uses5.2 Chemical Weathering ... The equation shown here is for olivine, but it could apply to almost any other ferromagnesian silicate, including pyroxene, amphibole, or biotite. Iron in the sulphide minerals (e.g., pyrite) can also be oxidized in this way. And the mineral hematite is not the only possible end result, as there is a wide range of ...As an example, the chemical formula for galena is PbS. That means there is one atom of sulfur to each atom of lead. However in reality, galena crystals usually contain considerably more sulfur than a 1 to 1 ratio with the lead would call for. The same is …Empirical Formulas. An empirical formula tells us the relative ratios of different atoms in a compound. The ratios hold true on the molar level as well. Thus, H 2 O is composed of two atoms of hydrogen and 1 atom of oxygen. Likewise, 1.0 mole of H 2 O is composed of 2.0 moles of hydrogen and 1.0 mole of oxygen.We can also work backwards from molar …5.2 Chemical Weathering ... The equation shown here is for olivine, but it could apply to almost any other ferromagnesian silicate, including pyroxene, amphibole, or biotite. Iron in the sulphide minerals (e.g., pyrite) can also be oxidized in this way. And the mineral hematite is not the only possible end result, as there is a wide range of ...Temperatures of formation for Barika sulfides estimated based on sulfur isotope values for coexisting galena-sphalerite (Δ = 2–4.8‰) and galena-pyrite (Δ = −3.3 to −5.4‰) pairs range from 146 to 293 °C, and these are consistent with fluid inclusion homogenization temperatures.Galena is a mineral composed primarily of lead(II) sulfide (PbS). It has been used for thousands of years as a source of lead, silver, and sometimes as a semiprecious stone. Here are some of the chemical, physical, and optical properties of galena: Chemical Properties: Chemical Formula: PbS (Lead Sulfide) Molecular Weight: 239.27 g/mol; Crystal ...23-Aug-2013 ... Lead sulfide is an inorganic compound with the chemical formula PbS. It is also known as galena, which is the principal ore and important ...Roasting of galena (PbS): The concentrated ore is roasted at a moderate temperature in a reverberatory furnace and in a limited supply of air. The balanced chemical equations are as given below. 2 P b S + 3 O 2 → 2 P b O + 2 S O 2 ↑ P b S + 2 O 2 → P b S O 4 .Galena has metallic to lead-gray, cube-shaped crystals that break into cubic, right-angled fragments. It is an ore—a mineral of economic value—that was once mined in southeastern Kansas for its lead content. The Tri-State mining district, which includes the far southeastern corner of the state, was formerly one of the most important lead ... General Hematite Information : Chemical Formula: Fe2O3 : Composition: Molecular Weight = 159.69 gm Iron 69.94 % Fe 100.00 % Fe 2 O 3: Oxygen 30.06 % O: 100.00 % 100.00 % = TOTAL OXIDEAug 5, 2018 · Systematic (IUPAC) Name: copper (II) sulfate pentahydrate. Common Names: copper (II) sulfate, copper (II) sulfate, cupric sulfate, cupric sulfate. Vernacular Name: copper sulfate, copper sulfate. Archaic Name: blue vitriol, bluestone, copper vitriol. CAS Number: 7758-99-8. There are many ways to name a chemical.General Galena Information : Chemical Formula: PbS : Composition: Molecular Weight = 239.27 gm Lead 86.60 % Pb Sulfur 13.40 % S _____ 100.00 % : Empirical Formula: PbS : Environment: Lead sulfide ore veins, and disseminated in igneous and sedimentary rocks. IMA Status: Valid Species (Pre-IMA) Prehistoric : Locality:The chemical formula of galena is PbS (lead sulfide). It belongs to the isometric crystal system, most common crystal shapes are cubes, octahedrons, and their combinations. The dodecahedron crystal shapes are much less common, over 40 galena crystal shapes are known. Twinning is common on {111} (spinel law twins).Galena is also known as lead glance. Its chemical formula is PbS. It is the most abundant Sulphide mineral. so, Galena is an importnt minerl of Pb(Lead)Wood does not have a chemical formula because it is not an individual chemical compound but is made up of many chemical structures. Within its cellular structure, there are three chemical components which are principally composed of carbon,...Pure limestone is made up of two component minerals: calcium carbonate and calcium-magnesium carbonate. The chemical formula for calcium carbonate is CaCO3. The chemical formula for calcium-magnesium carbonate is CaMg(CO3)2.2 days ago · Galena is the most abundant lead mineral, has been mined for millennia, and remains our major source of that metal. It is a metallic, …7.1 Drug Indication. Urea is used topically for debridement and promotion of normal healing of hyperkeratotic surface lesions, particularly where healing is retarded by local infection, necrotic tissue, fibrinous or purulent debris or eschar. Urea is useful for the treatment of hyperkeratotic conditions such as dry, rough skin, dermatitis .... Apr 23, 2023 · The chemical formula (Zn, Fe) of sphalerite is S. It is a zinc sulphide containing a variable amount of iron instead of zinc in the mineral lattice. The iron content …Summarize this article for a 10 years old. SHOW ALL QUESTIONS. Lead (II) sulfide (also spelled sulphide) is an inorganic compound with the formula Pb S. Galena is the principal ore and the most important compound of lead. It is a semiconducting material with niche uses. Lead (II) sulfide. Troilite has a chemical composition of FeS, while pyrrhotite's chemical composition is Fe (1-x) S. Pyrrhotite is deficient in iron because some of the iron sites in its crystal lattice are vacant (empty). That is why the iron in the formula has a subscript of 1-x. The value of "X" in the chemical formula of pyrrhotite can range between 1 and 0.17.Jul 7, 2023 · Chemical Equations. As shown in Figure 3.1.1 3.1. 1, applying a small amount of heat to a pile of orange ammonium dichromate powder results in a vigorous reaction known as the ammonium dichromate volcano. Heat, light, and gas are produced as a large pile of fluffy green chromium (III) oxide forms.Aug 5, 2018 · Systematic (IUPAC) Name: copper (II) sulfate pentahydrate. Common Names: copper (II) sulfate, copper (II) sulfate, cupric sulfate, cupric sulfate. Vernacular Name: copper sulfate, copper sulfate. Archaic Name: blue vitriol, bluestone, copper vitriol. CAS Number: 7758-99-8. There are many ways to name a chemical.Sulfur, the tenth most abundant element in the universe, has been known since ancient times. Sometime around 1777, Antoine Lavoisier convinced the rest of the scientific community that sulfur was an element. Sulfur is a component of many common minerals, such as galena (PbS), gypsum (CaSO 4 ·2(H 2 O), pyrite (FeS 2), sphalerite (ZnS or …Galena is the crystalline form of lead sulfide, PbS. It is in the cubic system and often forms beautiful silvery cubic crystals that may display twinning or steps. Galena is the major mineral source of lead. It forms beautiful crystals in the cubic system, many of which are prized by collectors.Galena is a rocksalt group, sulfide mineral with a chemical formula of PbS. Find facts and data about Galena.Galena is a lead sulfide mineral with a chemical composition of PbS. It is the world's primary ...minerals classified. grouped by chemistry, specifically the anions within the chemical formula. F. T/F -- Diamond and graphite are both poly-morphs of pure silicon. chloride differ chlorine. Chloride is chlorine's anion. ore minerals. Minerals utilized by humans as a source of metal. 2 type polarity bonds.The chemical formula for sulfuric acid is \(\ce{H_2SO_4}\). Summary. A chemical symbol is a one- or two-letter designation of an element. Compounds are combinations of two or more elements. A chemical formula is an expression that shows the elements in a compound and the relative proportions of those elements.Apr 1, 2019 · The chemical formula of galena is PbS (lead sulfide). It belongs to the isometric crystal system, most common crystal shapes are cubes, octahedrons, and their combinations. The dodecahedron crystal shapes are much less common, over 40 galena crystal shapes are known. Chemical formula No data bPb(NO3)2 PbOa Pb3O4e Chemical structure Not applicable Not applicable Not applicable . CAS Registry Number 12709-98-7: a: 10099-74-8: b: 1317-36-8: a: 1314-41-6: d: Pb O Pb O O Pb O Pb O O Pb O O Pb: LEAD 348 ... The most important Pb mineral is galena (PbS). Other common Pb-containing minerals include …The most common sulfide crystalling in this manner is galena (PbS), the ore mineral of lead. A type of packing that involves two sulfide ions in each of the octahedral positions in the sodium chloride structure is the pyrite structure. This is a high-symmetry structure characteristic of the iron sulfide, pyrite (FeS 2 O). Anglesite. Anglesite is a lead sulfate mineral with the chemical formula PbSO 4. It occurs as an oxidation product of primary lead sulfide ore, galena. Anglesite occurs as prismatic orthorhombic crystals and earthy masses, and is isomorphous with barite and celestine. It contains 74% of lead by mass and therefore has a high specific gravity of 6.3.Galena has been mined for lead and silver since the time of the Romans. It is the mineral form of lead sulfide. The chemical formula is PbS.What is the maximum mass of pure lead that could be extracted from 7.5 kg of galena lead ore with the chemical formula PbS? Be sure your answer has the unit symbol, if necessary, and rounded to the correct number of significant digits.Galena is a rocksalt group, sulfide mineral with a chemical formula of PbS. Find facts and data about Galena.Galena has metallic to lead-gray, cube-shaped crystals that break into cubic, right-angled fragments. It is an ore—a mineral of economic value—that was once mined in southeastern Kansas for its lead content. The Tri-State mining district, which includes the far southeastern corner of the state, was formerly one of the most important lead ... Word Equation. Galena + Dioxygen = Lead (Ii) Oxide + Sulfur Dioxide. PbS + O2 = PbO + SO2 is a Double Displacement (Metathesis) reaction where two moles of Galena [PbS] and three moles of Dioxygen [O 2] react to form two moles of Lead (Ii) Oxide [PbO] and two moles of Sulfur Dioxide [SO 2] Show Chemical Structure Image.chemical transformations in the materials for the . ... galena surface due to the high affinity of depressants. 1. ... Structural formula of dixanthogen .Galena's chemical formula is PbS. This expresses that a lead sulfide molecule is composed of one lead (Pb) cation (positive ion) and one sulfur (S) anion. Explanation: if helpful mark me as the brainliest pleaseThis problem has been solved! You'll get a detailed solution from a subject matter expert that helps you learn core concepts. Question: What is the maximum mass of pure lead that could be extracted from 1.0kg of galena, a lead ore with the chemical formula PbS? Be sure your answer has a unit symbol, if necessary, and is rounded to the correct ... Chemical formula. In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and plus (+) and minus (−) signs.chemical formula, any of several kinds of expressions of the composition or structure of chemical compounds. The forms commonly encountered are empirical, molecular, structural, and projection formulas. An empirical formula consists of symbols representing elements in a compound, such as Na for sodium and Cl for chlorine, and subscripts ...Oct 29, 2009 · Pyrite is iron ore while galena is lead ore. This is the main difference between them. The chemical formula of pyrite is FeS2; it is sulfide compound of iron where as galena is sulfide compound of lead with the chemical formula PbS. The color of galena may vary from light gray to dark gray while pyrite is generally brass yellow in color. Chemistry questions and answers. What is the maximum mass of pure lead that could be extracted from 2.0 kg of galena, a lead ore with the chemical formula PbS? Be sure your answer has a unit symbol, if necessary, and is rounded to the carrect number of significant digits.We're toid oxygen is the most coenmon element in the Earth's solid crust.Minerals (G-M) » Minerals (O-S) » Kirkby Teaching Materials Galena Sulfide mineral About Galena In Our Earth In Our Society In Our Future In the Upper Midwest Gallery Galena Properties Commonly confused with... Did you know... Galena is the most abundant lead mineral, has been mined for millennia, and remains our major source of that metal.ScienceChemistryWhat is the maximum mass of pure lead that could be extracted from 55.0 g of galena, a lead ore with the chemical formula PbS? Be sure your ...Write chemical formula of galena. Maharashtra State Board HSC Science (Electronics) 12th Standard Board Exam. Question Papers 212. Textbook Solutions 10257. MCQ Online Mock Tests 60. Important Solutions 4650. Concept Notes & Videos 417. Time Tables 26. Syllabus. Write chemical formula of galena. - Chemistry.Galena. Galena. Galena lanita. Galena crystal from Galena, Kansas. General. Category, Sulfides. Chemical formula · lead sulfide (PbS). Identification. Color ...Gypsum is the mineral that includes in its structure Sulfate ion, which makes it a sulfate mineral, and of all the sulfate minerals, Gypsum is the most common. Gypsum is composed of hydrated calcium sulfate, and its chemical formula is CaSO4.2H2O. It is a natural salt mineral, that is to say, an evaporite mineral, and is mostly found along with ...Mindat.org - Mines, Minerals and MoreStudy with Quizlet and memorize flashcards containing terms like Mass, Mass is measured in _____., Mass is measured using a _____ _____ _____. and more.Study with Quizlet and memorize flashcards containing terms like Sphalerite (Class: sulfide), Gypsum (Class: sulfate), Galena (Class: sulfide) and more. Scheduled maintenance: Saturday, September 10 from 11PM to 12AM PDT0. FORMAULAE OF COMMON MINERALS ; Pyrite. FeS · Calcite ; Chalcopyrite. CuFeS · Siderite ; Sphalerite. ZnS. Magnesite ; Galena. PbS. Dolomite ; Cinnabar. HgS.Aug 31, 2023 · 1. Which of the following is the most common lead ore? a. Galena b. Sphalerite c. Chalcopyrite d. Pyrite 2. What is the chemical formula for Galena, a lead ore? a. PbS b. PbO c. PbSe d. PbSO4 3. How is lead extracted from lead ores? a. Smelting b. Leaching c. Fractional distillati...Galena is a gray, cubic, shiny, dense mineral most commonly associated with lead. It is one of the earliest minerals used by humans, and one of the most abundant sulfide minerals on the Earth. Relation to Mining. Galena is still mined today in large quantities, not only for lead, but also for silver. UsesJNTU Hyderabad B.Tech Non-Ferrous Extractive Metallurgy Mid - I, September - 2014 Question PaperBelow is a listorted by mineral name of 900 commonly available minerals and mineral synonyms. For each mineral species we provided a quick reference of chemical formula, mineral group or mineral series, mineral class and, subclass, and the Dana locality or type locality where the original mineral was first found and described.Study with Quizlet and memorize flashcards containing terms like Mass, Mass is measured in _____., Mass is measured using a _____ _____ _____. and more.09-Aug-2023 ... Galena not a rock its a Economic mineral of lead. Formula of Galena is PbS. Galena and Sphalerite(ZnS) Found togather at Hydrothemal deposits.Galena Meanings, Zodiacs, Planets, Elements, Colors, Chakras, and more. Science & Origin of GalenaGalena is a lead sulfide mineral that crystallizes in the form of masses, cubes, octahedrons, and fibrous layers. Today, it's the most important lead ore when it comes to the production of goods. This mineral was first described back in 77 A.D. by Gaius Plinius Secundus (Pliny the Elder). He named ...Mg2+Cl−Cl− (4.3.2) (4.3.2) Mg 2 + Cl − Cl −. Now the positive and negative charges are balanced. We could write the chemical formula for this ionic compound as MgClCl MgClCl, but the convention is to use a numerical subscript when there is more than one ion of a given type— MgCl2 MgCl 2.Chemistry questions and answers. What is the maximum mass of pure lead that could be extracted from 2.0 kg of galena, a lead ore with the chemical formula PbS? Be sure your answer has a unit symbol, if necessary, and is rounded to the carrect number of significant digits.We're toid oxygen is the most coenmon element in the Earth's solid crust.Question: Part A Referring to the table given below, write a balanced equation for the dissolving of galena in hydrochloric acid. The products are hydrogen sulfide gas and load (II) chloride. Table Some Nonsilicate Minerals of Economic Importance Mineral Type Name Chemical Formula Source and/or Use Hematite FeO3 Ore of iron; pigment Oxide ...chemicals for industrial and home consumers. U.S. production occurs in Florida, North Carolina, Idaho and Utah. The U.S. is a major producer. It was not import reliant in 2012. Potash A carbonate of potassium; used as a fertilizer, in medicine, in the chemical industry and to produce decorative color effects on brass, bronze and nickel. TheChemical Formula: Fe++Fe+++2O4 : Composition: ... Empirical Formula: Fe 3+ 2 Fe 2+ O 4: Environment: Common accessory mineral in igneous and metamorphic rocks. Can be ... anglesite, naturally occurring lead sulfate (PbSO 4 ). A common secondary mineral that is a minor ore of lead, it is usually formed by the oxidation of galena and often forms a concentrically banded mass surrounding a core of unaltered galena. The formation of cerussite (lead carbonate) often accompanies or follows the formation of anglesite.What is the chemical formula for galena? A PbS. 8 Q What is the chemical formula for native sulphur? A S. 9 Q What is the chemical formula for native copper? A Cu. 10 Q What is the name of the mineral with the chemical formula FeS₂? A pyrite. 11 Q What is the name of the mineral with the chemical formula CaCO ...Galena's chemical formula is PbS. This expresses that a lead sulfide molecule is composed of one lead (Pb) cation (positive ion) and one sulfur (S) anion. Each ion forms an octahedral structure by ...Since the greatest common divisor of the ratio of atoms in Galena, PbS is 1, it is already simplified and its empirical formula is also PbS. Calculators.