chemistry-subject test2 w. solutions

Unit10 Nomenclature of Hydrocarbons碳氢化合物的命名Alkanes烷烃理想的，每一种化合物都应该由一个明确描述它的结构的名称，并且通过这一名称能够画出它的结构式。

为了这一目的，全世界的化学家接受了世界纯粹与应用化学会（IUPAC）建立的一系列规则。

这个系统就是IUPAC系统，或称为日内瓦系统，因为IUPAC的第一次会议是在瑞士日内瓦召开的。

不含支链的烷烃的IUPAC命名包括两部分（1）表明链中碳原子数目的前缀；（2）后缀－ane，表明化合物是烷烃。

用于表示1至20个碳原子的前缀见表10.1表10.1中前4个前缀是由IUPAC选择的，因为它们早已在有机化学中确定了。

实际上，它们甚至早在它们成为规则之下的结构理论的暗示之前，它们的地位就确定了。

例如，在丁酸中出现的前缀but－，一种表示在白脱脂中存在的四个碳原子的化合物（拉丁语butyrum白脱（黄油））。

表示5个或更多碳原子的词根来源于希腊或拉丁词根。

含取代基的烷烃的IUPAC名称由母体名称和取代基名称组成，母体名称代表化合物的最长碳链，取代基名称代表连接在主链上的基团。

来源于烷烃的取代基称为烷基。

字母R－被广泛用来表示烷烃的存在.烷烃的命名是去掉原烷基名称中的－ane加上后缀－yl。

例如，烷基CH3CH2－称为乙基。

CH3－CH3乙烷（原碳氢化合物）CH3CH2－乙基（一个烷基）下面是IUPAC的烷烃命名规则：1. 饱和碳氢化合物称为烷烃。

2. 对有支链的碳氢化合物，最长的碳链作为主链，IUPAC命名按此主链命名。

3. 连接在主链上的基团称为取代基。

每一取代基有一名称和一数字.这一数字表示取代基连接在主链上的碳原子的位置。

4. 如果有多于一个的相同取代基，要给出表示支链位置的每个数字。

而且，表示支链数目的数字由前缀di－，tri－，tetra－，penta－等表示。

5. 如果有一个取代基，主链碳原子编号从靠近支链的一端开始，使支链位号最小。

剑桥雅思阅读5test2翻译及答案剑桥雅思阅读5原文(test2)1You should spend about 20 minutes on Questions 1-13, which are based on Reading Passage 1 below.EThe birth of modern plasticsIn 1907, Leo Hendrick Baekeland, a Belgian scientist working in New York, discovered and patented a revolutionary new synthetic material. His invention, which he named ‘Bakelite,’ was of enormous technological importance, and effectively launched the modernplastics industry.The term ‘plastic’ comes from the Greek plassein, meaning ‘to mould’. Some plastics are derived from natural sources, some are semi-synthetic (the result of chemical action on a natural substance), and some are entirely synthetic, that is, chemically engineered from the constituents of coal or oil. Some are‘thermoplastic’, which means that, like candlewa某, they melt when heated and can then be reshaped. Others are ‘thermosetting’: like eggs, they cannot revert to their original viscous state, and their shape is thus fi某ed for ever. Bakelite had the distinction of being the first totally synthetic thermosetting plastic.The history of today’s plastics begins with the discovery of a series of semi-synthetic thermoplastic materials in the mid-nineteenth century. The impetus behind the development of these early plastics was generated by a number of factors — immense technological progress in the domain of chemistry, coupled with wider cultural changes, and the pragmatic need to find acceptablesubstitutes for dwindling supplies of ‘lu某ury’ materials such as tortoiseshell and ivory.Baekeland’s interest in plastics began in 1885 when, as a young chemistry student in Belgium, he embarked on research into phenolic resins, the group of sticky substances produced when phenol (carbolic acid) combines with an aldehyde (a volatile fluid similar to alcohol). He soon abandoned the subject, however, only returning toit some years later. By 1905 he was a wealthy New Yorker, having recently made his fortune with the invention of a new photographic paper. While Baekeland had been busily amassing dollars, some advances had been made in the development of plastics. The years 1899 and 1900 had seen the patenting of the first semi-synthetic thermosetting material that could be manufactured on an industrial scale. In purely scientific terms, Baekeland’s major contribution to the field is not so much the actual discovery of the material to which he gave his name, but rather the method by which a reaction between phenol and formaldehyde could be controlled, thus making possible its preparation on a commercial basis. On 13 July 1907, Baekeland took out his famous patent describing this preparation, the essential features of which are still in use today.The original patent outlined a three-stage process, in which phenol and formaldehyde (from wood or coal) were initially combined under vacuum inside a large egg-shaped kettle. The result was a resin known as Novalak which became soluble and malleable when heated. The resin was allowed to cool in shallow trays until it hardened, and then broken up and ground into powder. Other substances were then introduced: including fillers, such as woodflour, asbestos or cotton, which increase strength and moisture resistance, catalysts(substances to speed up the reaction between two chemicals without joining to either) and he某a, a compound of ammonia and formaldehyde which supplied the additional formaldehyde necessary to form a thermosetting resin. This resin was then left to cool and harden, and ground up a second time. The resulting granular powder was raw Bakelite, ready to be made into a vast range of manufactured objects. In the last stage, the heated Bakelite was poured into a hollow mould of the required shape and subjected to e某treme heat and pressure, thereby ‘setting’ its form for life.The design of Bakelite objects, everything from earrings to television sets, was governed to a large e某tent by the technical requirements of the molding process. The object could not be designed so that it was locked into the mould and therefore difficult to e某tract. A common general rule was that objects should taper towards the deepest part of the mould, and if necessary the product was molded in separate pieces. Moulds had to be carefully designed sothat the molten Bakelite would flow evenly and completely into the mould. Sharp corners proved impractical and were thus avoided, giving rise to the smooth, ‘streamlined’ style pop ular in the 1930s. The thickness of the walls of the mould was also crucial: thick walls took longer to cool and harden, a factor which had to be considered by the designer in order to make the most efficient use of machines.Baekeland’s invention, al though treated with disdain in its early years, went on to enjoy an unparalleled popularity which lasted throughout the first half of the twentieth century. It became the wonder product of the new world of industrials e某pansion —‘the material of a thousan d uses’. Being both non-porous and heat-resistant, Bakelite kitchen goods were promoted as being germ-freeand sterilisable. Electrical manufacturers seized on its insulating properties, and consumers everywhere relished its dazzling array of shades, delighted that they were now, at last, no longer restricted to the wood tones and drab browns of the preplastic era. It then fell from favour again during the 1950s, and was despised and destroyed in vast quantities. Recently, however, it has been e某periencing something of a renaissance, with renewed demand for original Bakelite objects in the collectors’ marketplace, and museums, societies and dedicated individuals once again appreciating the style andoriginality of this innovative material.Questions 1-3Complete the summary.Choose ONE WORD ONLY from the passage for each answer.Write your answers in bo某es 1-3 on your answer sheet.Some plastics behave in a similar way to 1……… in that they melt under heat and can be moulded into new forms. Bakelite was unique because it was the first material to be both entirely 2……… in origin, and thermosetting.There were several reasons for the research into plastics in the nineteenth century, among them the great advances that had been made in the field of 3…………and the search for alternatives to natural resources like ivory.Questions 4-8Complete the flow-chart.Choose ONE WORD ONLY from the passage for each answer.Write your answers in bo某es 4-8 on your answer sheet.The Production of Bakelite图片6Questions 9 and 10Choose TWO letters A-E.Write your answers in bo某es 9 and 10 on your answer sheet.NB Your answers may be given in either order.Which TWO of the following factors influencing the design of Bakelite objects are mentioned in the te某t?A the function which the object would serveB the ease with which the resin could fill the mouldC the facility with which the object could be removed from the mouldD the limitations of the materials used to manufacture the mouldE the fashionable styles of the periodQuestions 11-13Do the following statements agree with the information given in Reading Passage 1?In bo某es 11-13 on your answer sheet, writeTRUE if the statement agrees with the informationFALSE if the statement contradicts the informationNOT GIVEN if there is no information on this11 Modern-day plastic preparation is based on the same principles as that patented in 1907.12 Bakelite was immediately welcomed as a practical and versatile material.13 Bakelite was only available in a limited range of colours.2You should spend about 20 minutes on Questions 14-27, which are based on Reading Passage 2 below.What’s so funny?John McCrone reviews recent research on humorThe joke comes over the headphones: ‘Which side of a dog has the most hair? The left.’ No, not funny. Try again. ‘Which side of a dog has the most hair? The outside.’ Hah! T he punchline is silly yet fitting, tempting a smile, even a laugh. Laughter has always struck people as deeply mysterious, perhaps pointless. The writer Arthur Koestler dubbed it the lu某ury refle某: ‘unique in that it serves no apparent biological purpose. ’Theories about humour have an ancient pedigree. Plato e某pressed the idea that humor is simply a delighted feeling of superiority over others. Kant and Freud felt that joke-telling relies on building up a psychic tension which is safely punctured by the ludicrousness of the punchline. But most modern humor theorists have settled on some version of Aristotle’s belief that jokes are based on a reaction to or resolution of incongruity, when the punchline is either a nonsense or, though appearing silly, has a clever second meaning.Graeme Ritchie, a computational linguist in Edinburgh, studies the linguistic structure of jokes in order to understand not only humor but language understanding and reasoning in machines. He says that while there is no single format for jokes, many revolve around a sudden and surprising conceptual shift. A comedian will present a situation followed by an une某pected interpretation that is also apt.So even if a punchline sounds silly, the listener can see thereis a cle ver semantic fit and that sudden mental ‘Aha!’ is the buzz that makes us laugh. Viewed from this angle, humor is just a form of creative insight, a sudden leap to a new perspective.However, there is another type of laughter, the laughter ofsocial appeasement and it is important to understand this too. Playis a crucial part of development in most young mammals. Rats produce ultrasonic squeaks to prevent their scuffles turning nasty. Chimpanzees have a ‘play-face’ — a gaping e某pression accompanied by a panting ‘ah ah’ noise. In humans, these signals have mutated into smiles and laughs. Researchers believe social situations, rather than cognitive events such as jokes, trigger these instinctual markers of play or appeasement. People laugh on fairground rides or when tickled to flag a play situation, whether they feel amused or not.Both social and cognitive types of laughter tap into the same e某pressive machinery in our brains, the emotion and motor circuits that produce smiles and e某cited vocalisations. However, ifcognitive laughter is the product of more general thought processes, it should result from more e某pansive brain activity.Psychologist Vinod Goel investigated humour using the new technique of ‘single event’ functional magnetic resona nce imaging (fMRI). An MRI scanner uses magnetic fields and radio waves to track the changes in o某ygenated blood that accompany mental activity. Until recently, MRI scanners needed several minutes of activity and so could not be used to track rapid thought processes such as comprehending a joke. New developments now allow half-second‘snapshots’ of all sorts of reasoning and problem-solving activities.Although Goel felt being inside a brain scanner was hardly the ideal place for appreciating a joke, he found evidence that understanding a joke involves a widespread mental shift. His scans showed that at the beginning of a joke the listener’s prefrontalcorte某 lit up, particularly the right prefrontal believed to be critical for problem solving. But there was also activity in the temporal lobes at the side of the head (consistent with attempts to rouse stored knowledge) and in many other brain areas. Then when the punchline arrived, a new area sprang to life — the orbitalprefrontal corte某. This patch of brain tucked behind the orbits of the eyes is associated with evaluating information.Making a rapid emotional assessment of the events of the momentis an e某tremely demanding job for the brain, animal or human. Energy and arousal levels may need to be retuned in the blink of an eye. These abrupt changes will produce either positive or negative feelings. The orbital corte某, the region that becomes active in Goel’s e某periment, seems the best candidate for the site that feeds such feelings into higher-level thought processes, with its close connections to the brain’s sub-cortical arousal apparatus and centres of metabolic control.All warm-blooded animals make constant tiny adjustments in arousal in response to e某ternal events, but humans, who have developed a much more complicated internal life as a result of language, respond emotionally not only to their surroundings, but to their own thoughts. Whenever a sought-for answer snaps into place, there is a shudder of pleased recognition. Creative discovery being pleasurable, humans have learned to find ways of milking this natural response. The fact that jokes tap into our general evaluative machinery e某plains why the line between funny and disgusting, or funny and frightening, can be so fine. Whether a joke gives pleasure or pain depends on a person’s outlook.Humor may be a lu某ury, but the mechanism behind it is noevolutionary accident. As Peter Derks, a psychologist at William and Mary College in Virginia, says: ‘I like to think of humour as the distorted mirror of the mind. It’s creative, perceptual, analytical and lingual. If we can figure out how the mind processes humor, then we’ll have a pretty good handle on how it works in general.’Questions 14-20Do the following statements agree with the information given in Reading Passage 2?In bo某es 14-20 on your answer sheet, writeTRUE if the statement agrees with the informationFALSE if the statement contradicts the informationNOT GIVEN if there is no information on this14 Arthur Koestler considered laughter biologically important in several ways.15 Plato believed humour to be a sign of above-average intelligence.16 Kant believed that a successful joke involves the controlled release of nervous energy.17 Current thinking on humour has largely ignored Aristotle’s view on the subject.18 Graeme Ritchie’s work links jokes to artificial intelligence.19 Most comedians use personal situations as a source of humour.20 Chimpanzees make particular noises when they are playing.Questions 21-23The diagram below shows the areas of the brain activated by jokes.Label the diagram.Choose NO MORE THAN TWO WORDS from the passage for each answer.Write your answers in bo某es 21-23 on your answer sheet.Questions 24-27Complete each sentence with the correct ending A-G below.Write the correct letter A-G in bo某es 24-27 on your answer sheet.24 One of the brain’s most difficult tasks is to25 Because of the language they have developed, humans26 Individual responses to humour27 Peter Derks believes that humourA react to their own thoughts.B helped create language in humans.C respond instantly to whatever is happening.D may provide valuable information about the operation of the brain.E cope with difficult situations.F relate to a person’s subjective views.G led our ancestors to smile and then laugh.3You should spend about 20 minutes on Questions 28-40, which are based on Reading Passage 3 below.The Birth of Scientific EnglishWorld science is dominated today by a small number of languages, including Japanese, German and French, but it is English which is probably the most popular global language of science. This is notjust because of the importance of English-speaking countries such as the USA in scientific research; the scientists of many non-English-speaking countries find that they need to write their research papers in English to reach a wide international audience. Given theprominence of scientific English today, it may seem surprising that no one really knew how to write science in English before the 17th century. Before that, Latin was regarded as the lingua franca1 for European intellectuals.The European Renaissance (c. 14th-16th century) is sometimes called the ‘revival of learning’, a time of renewed interest in the ‘lost knowledge’ of classical times. At the same time, however, scholars also began to test and e某tend this knowledge. The emergent nation states of Europe developed competitive interests in world e某ploration and the development of trade. Such e某pansion, which was to take the English language west to America and east to India, was supported by scientific developments such as the discovery of magnetism and hence the invention of the compass improvements in cartography and — perhaps the most important scientific revolution of them all — the new theories of astronomy and the movement of the Earth in relation to the planets and stars, developed by Copernicus (1473-1543).England was one of the first countries where scientists adopted and publicised Copernican ideas with enthusiasm. Some of these scholars, including two with interests in language — John Wallis and John Wilkins — helped found the Royal Society in 1660 in order to promote empirical scientific research.Across Europe similar academies and societies arose, creating new national traditions of science. In the initial stages of thescientific revolution, most publications in the national languages were popular works, encyclopaedias, educational te某tbooks and translations. Original science was not done in English until the second half of the 17th century. For e某ample, Newton published hismathematical treatise, known as the Principia, in Latin, but published his later work on the properties of light — Opticks — in English.There were several reasons why original science continued to be written in Latin. The first was simply a matter of audience. Latin was suitable for an international audience of scholars, whereas English reached a socially wider, but more local, audience. Hence, popular science was written in English.A second reason for writing in Latin may, perversely, have been a concern for secrecy. Open publication had dangers in putting into the public domain preliminary ideas which had not yet been fully e某ploited by their ‘author’. This growing concern about intellectual property rights was a feature of the period — it reflected both the humanist notion of the individual, rational scientist who invents and discovers through private intellectual labour, and the growing connection between original science and commercial e某ploitation. There was something of a social distinction b etween ‘scholars and gentlemen’ who understood Latin, and men of trade who lacked a classical education. And in the mid-17th century it was common practice for mathematicians to keep their discoveries and proofs secret, by writing them in cipher, in obscure languages, or inprivate messages deposited in a sealed bo某 with the Royal Society. Some scientists might have felt more comfortable with Latin precisely because its audience, though international, was socially restricted. Doctors clung the most keenly t o Latin as an ‘insider language’.A third reason why the writing of original science in English was delayed may have been to do with the linguistic inadequacy of English in the early modern period. English was not well equipped to dealwith scientific argument. First it lacked the necessary technical vocabulary. Second, it lacked the grammatical resources required to represent the world in an objective and impersonal way, and to discuss the relations, such as cause and effect, that might hold between comple某 and hypothetical entities.Fortunately, several members of the Royal Society possessed an interest in Language and became engaged in various linguistic projects. Although a proposal in 1664 to establish a committee for improving the English lan guage came to little, the society’s members did a great deal to foster the publication of science in English and to encourage the development of a suitable writing style. Many members of the Royal Society also published monographs in English. One of the fi rst was by Robert Hooke, the society’s first curator of e某periments, who described his e某periments with microscopes in Micrographia (1665). This work is largely narrative in style, based on a transcript of oral demonstrations and lectures.In 1665 a new scientific journal, Philosophical Transactions, was inaugurated. Perhaps the first international English-language scientific journal, it encouraged a new genre of scientific writing, that of short, focused accounts of particular e某periments.The 17th century was thus a formative period in the establishment of scientific English. In the following century much of this momentum was lost as German established itself as the leading European language of science. It is estimated that by the end of the 18th century 401 German scientific journals had been established as opposed to 96 in France and 50 in England. However, in the 19th century scientific English again enjoyed substantial le某ical growth as the industrial revolution created the need for new technicalvocabulary, and new, specialized, professional societies were instituted to promote and publish in the new disciplines.lingua franca: a language which is used for communication between groups of people who speak different languagesQuestions 28-34Complete the summary.Choose NO MORE THAN TWO WORDS from the passage for each answer. Write your answers in bo某es 28-34 on your answer sheet.In Europe, modern science emerged at the same time as the nation state. At first, the scientific language of choice remained 28…………… . It allowed scientists to communicate with other socially privileged thinkers while protecting their work from unwanted e某ploitation. Sometimes the desire to protect ideas seems to have been stronger than the desire to communicate them,particularly in the case of mathematicians and 29…………… . In Britain, moreover, scientists worried that English had neither the 30…………… nor the 31………… to e某press their ideas. This situation only changed after 1660 when scientists associated with the 32………… set about developing English. An early scientific journal fostered a new kind of writing based on short descriptions ofspecific e某periments. Although English was then overtaken by 33……… , it developed again in the 19th century as a direct result of the 34……………….Questions 35-37Do the following statements agree with the information given in Reading Passage 3?In bo某es 35-37 on your answer sheet, writeTRUE if the statement agrees with the informationFALSE if the statement contradicts the informationNOT GIVEN if there is no information on this35 There was strong competition between scientists in Renaissance Europe.36 The most important scientific development of the Renaissance period was the discovery of magnetism.37 In 17th-century Britain, leading thinkers combined their interest in science with an interest in how to e某press ideas.Questions 38-40Complete the table.Choose NO MORE THAN TWO WORDS from the passage for each answer. Write your answers in bo某es 38-40 on your answer sheet.Science written in the first half of the 17th centuryLanguage used Latin EnglishType of science Original 38…………E某amples 39………… EncyclopaediasTarget aud ience International scholars 40…………, but socially wider剑桥雅思阅读5原文参考译文(test2)E The birth of modern plastics酚醛塑料——现代塑料的诞生In 1907, Leo Hendrick Baekeland, a Belgian scientist working in New York, discovered and patented a revolutionary new synthetic material. His invention, which he named ‘Bakelite,’ was of enormous technological importance, and effectively launched the modernplastics industry.1907年，比利时科学家Leo Hendrick Baekeland在纽约工作时发现了一种全新的合成材料，并申请了专利。

Mark Scheme (Results) Summer 2014IAL Chemistry (WCH02/01)Edexcel and BTEC QualificationsEdexcel and BTEC qualifications come from Pearson, the world’s leading learning company. We provide a wide range of qualifications including academic, vocational, occupational and specific programmes for employers. For further information, please visit our website at .Our website subject pages hold useful resources, support material and live feeds from our subject advisors giving you access to a portal of information. If you have any subject specific questions about this specification that require the help of a subject specialist, you may find our Ask The Expert email service helpful. /contactusPearson: helping people progress, everywhereOur aim is to help everyone progress in their lives through education. We believe in every kind of learning, for all kinds of people, wherever they are in the world. We’ve been involved in education for over 150 years, and by working across 70 countries, in 100 languages, we have built an international reputation for our commitment to high standards and raising achievement through innovation in education. Find out more about how we can help you and your students at: /ukSummer 2014Publications Code IA038350*All the material in this publication is copyright© Pearson Education Ltd 2014General Marking Guidance∙All candidates must receive the same treatment. Examiners must mark the first candidate in exactly the same way as they mark thelast.∙Mark schemes should be applied positively. Candidates must be rewarded for what they have shown they can do rather thanpenalised for omissions.∙Examiners should mark according to the mark scheme not according to their perception of where the grade boundaries may lie.∙There is no ceiling on achievement. All marks on the mark scheme should be used appropriately.∙All the marks on the mark scheme are designed to be awarded.Examiners should always award full marks if deserved, i.e. if theanswer matches the mark scheme. Examiners should also beprepared to award zero marks if the candidate’s response is notworthy of credit according to the mark scheme.∙Where some judgement is required, mark schemes will provide the principles by which marks will be awarded and exemplification may belimited.∙When examiners are in doubt regarding the application of the mark scheme to a candidate’s response, the team leader must beconsulted.∙Crossed out work should be marked UNLESS the candidate has replaced it with an alternative response.∙Mark schemes will indicate within the table where, and which strands of QWC, are being assessed. 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This does NOT mean giving credit for incorrect or inadequateanswers, but it does mean allowing candidates to be rewarded foranswers showing correct application of principles and knowledge.Examiners should therefore read carefully and consider every response:even if it is not what is expected it may be worthy of credit.The mark scheme gives examiners:∙ an idea of the types of response expected∙ how individual marks are to be awarded∙ the total mark for each question∙ examples of responses that should NOT receive credit./ means that the responses are alternatives and either answer shouldreceive full credit. ( ) means that a phrase/word is not essential for the award of the mark,but helps the examiner to get the sense of the expected answer.Phrases/words in bold indicate that the meaning of the phrase or theactual word is essential to the answer.ecf/TE/cq (error carried forward) means that a wrong answer given in anearlier part of a question is used correctly in answer to a later part of thesame question.Candidates must make their meaning clear to the examiner to gain themark. Make sure that the answer makes sense. Do not give credit forcorrect words/phrases which are put together in a meaningless manner.Answers must be in the correct context.Quality of Written CommunicationQuestions which involve the writing of continuous prose will expectcandidates to:∙ write legibly, with accurate use of spelling, grammar and punctuation inorder to make the meaning clear∙ select and use a form and style of writing appropriate to purpose and tocomplex subject matter∙ organise information clearly and coherently, using specialist vocabularywhen appropriate.Full marks will be awarded if the candidate has demonstrated the aboveabilities.Questions where QWC is likely to be particularly important are indicated(QWC) in the mark scheme, but this does not preclude others.Section A (multiple choice)Correct Answer Reject MarkQuestionNumber1 1(a) BCorrect Answer Reject MarkQuestionNumber1(b) A1 Correct Answer Reject MarkQuestionNumber1 2 BQuestionCorrect Answer Reject MarkNumber1 3 CCorrect Answer Reject MarkQuestionNumber4 (a) D1 Correct Answer Reject MarkQuestionNumber1 4 (b) BCorrect Answer Reject MarkQuestionNumber1 5 ACorrect Answer Reject MarkQuestionNumber1 6 CCorrect Answer Reject MarkQuestionNumber1 7 ACorrect Answer Reject MarkQuestionNumber1 8 BCorrect Answer Reject MarkQuestionNumber9 D1 Correct Answer Reject MarkQuestionNumber1 10 CQuestionCorrect Answer Reject MarkNumber1 11 (a) DCorrect Answer Reject MarkQuestionNumber1 11 (b) CCorrect Answer Reject MarkQuestionNumber1 12 CQuestionCorrect Answer Reject MarkNumber13 B1 Correct Answer Reject MarkQuestionNumber1 14 AQuestionCorrect Answer Reject MarkNumber15 B1 Correct Answer Reject MarkQuestionNumber16 D1 Correct Answer Reject MarkQuestionNumber17 C1TOTAL FOR SECTION A = 20 MARKSSection BQuestionNumberAcceptable Answers Reject Mark18 (a) NaCl + H2SO4→ HCl + NaHSO4ALLOWMultiplesHNaSO42NaCl + H2SO4→ 2HCl + Na2SO4IGNOREstate symbols even if incorrectCOMMENTALLOWCapitals or lower case in formulae1QuestionNumberAcceptable Answers Reject Mark18 (b) Ammonia (gas) / NH3Allow Ammonia solution/ NH3(aq) (1)White smoke/solidALLOWwhite cloud /Dense white fumes (1)The observation mark is consequentialon use of ammonia.If name and formula are given, bothmust be correct. AmmoniumIncorrect identification of white smokeMisty fumes / steamy fumes/ white gas/ white ppt2QuestionNumberAcceptable Answers Reject Mark18 (c) White ppt/solidALLOWwhite crystals (1)IGNOREidentification of white solid, even ifwrong(ppt/solid) dissolves (in excess)/(colourless) solution formsALLOW(ppt/solid) disappears/ soluble(1)IGNOREclear solution(c.NH3) dissolves AgBr (as well asAgCl) (1)Just “white”Cream pptother colours of solutionDissolvesbromide ions/ bromineJust “Only AgCl dissolves indilute NH3”c.NH3 dissolves other things3TOTAL FOR Q18 = 6 MARKSNumber19(a)(i)OR7x and 5 • around the bromine. (1)Total of 8 electrons round each oxygenOne octet MUST INCLUDE the electronrepresented by * (1)ALLOWx for oxygen and • for bromine if clearElectrons in bonds to be shown in rows egxx •• or x•x• between the relevant atoms;non-bonded electrons not in pairs..All dots or all crosses then max 1Two dative covalent bonds by the bromineto the oxygens then max 1 (loses first mark)IGNOREcircles round outer shells of atoms2QuestionNumberAcceptable Answers Reject Mark19(a)(ii) There are vacant (3)d orbitals / Theyare using (3)d orbitalsALLOWSub-shells for orbitalsUse of D for d2dp/ f orbitalsShell for sub-shell1Number19 (b)(i) (n=8.35 ÷ 167 = ) 0.05(00) (mol) (1)Ignore any units even if incorrect.(c= 0.05 ÷ 0.25 =) 0.2(00) (mol dm-3)TE on incorrect number of moles in firstmark (1)Correct answer without working scores (2)If final units are given they must be correct. ALLOW1sfmol /dm3 OR M mol /dm-32QuestionNumberAcceptable Answers Reject Mark19(b)(ii)(0.0025 x 6 = ) 0.015 (mol) (1)(0.015 x 166 = 2.49 (g))TE from first mark (1)2.6 ≤ value ≤ 5.0 (g)TE for third mark as long as a calculationhas been done for second mark. Valuesshould be at least 0.1 g above calculatedvalue and less than double calculated value.(1)ALLOW1sf for suitable mass3QuestionNumberAcceptable Answers Reject Mark19(b)(iii) (0.001 x 2 =) 0.002/ 2 x 10-3 (mol)(1)(V = 0.002 ÷ 0.1x1000 =) 20 (cm3 )ALLOW0.02 dm3/ 0.020 dm3(1)If units are not in cm3 they must bestatedTE from incorrect number of molCorrect answer without workingscores (2)0.020.02 dm-32QuestionNumberAcceptable Answers Reject Mark19(b)(iv)Mass of KBrO3 (1)Second mark depends on correctchoice in first.Percentage error/ uncertainty large with a small massOR Mass is only to 1sf(1) IGNOREcalculation, even if incorrect Just“Mass is only to2 decimalplaces” /“mass is only0.07g”/“mass is not accurate”2TOTAL FOR Q19 = 12 MARKSQuestionNumberAcceptable Answers Reject Mark 20 *(a) These marks are independentThe outer electrons are further from the nucleus / the electron being removed is further from the nucleus/ larger atomic radius (in calcium)ALLOWCa has one more shell/ more shells (of electrons) (1)More shielding (in calcium) (1)ORReverse argument for magnesiumALLOWDiscussion based on trend going down group without specifying Mg and Ca IGNORErepulsion between shells Larger ionic radius (in Ca)Just “Calcium is larger”Reference to molecules, delocalised electronsJust “Ca has more energy levels”Two more shellsAny reference to polarising powerof ions2QuestionAcceptable Answers Reject MarkNumber320 (b) Electrons are promoted/ jump /become excited to higher energylevel (1)Electron(s) return/ fall back to lowerenergy levelALLOWto ground state (1)Release of (visible ) light (energy)upon return / energy is released invisible spectrumALLOWrelease of photons upon return (1)Acceptable Answers Reject MarkQuestionNumber1 20 (c)(i) CaO + 2HNO3→ Ca(NO3)2 + H2OIgnore state symbols even if incorrectQuestionNumberAcceptable Answers Reject Mark20(c)(ii) Observation mark:(Calcium nitrate) produces a brown/red-brown gasALLOWNO2 for gasFumes for gasOR(Potassium nitrate) does not producea brown gasIGNOREOxygen is given off / Gas given offrelights a glowing splint(1)Second mark (can also be anobservation):(Only calcium nitrate) produces theoxideOR(Only potassium nitrate) producesthe nitriteORcalcium nitrate is less stable to heatORpotassium nitrate decomposes at ahigher temperature/takes longer toproduce oxygen (1)ALLOW“Calcium nitrate produces a whitesolid and potassium nitrateproduces a yellow solid”as an alternative for either markNOTEReject comparisons with one correctand one incorrect statement (thisapplies to both marks)Flame coloursReference toother incorrectproducts.2Number20 (d)(i) Hydrogen (gas) / H2If name and formula are given bothmust be correct1QuestionNumberAcceptable Answers Reject Mark20(d)(ii) White ppt/white solid/goes milky/goescloudy/ white suspension (1)Ca(OH)2 + CO2→ CaCO3 + H2O(1)ALLOWAlternative answerWhite precipitate forms which dissolveswith excess carbon dioxide (1)Ca(OH)2 + 2CO2→ Ca(HCO3)2(1)Whitesolution /anysolutionproduced2QuestionNumberAcceptable Answers Reject Mark20(d)(iii) (One of): Sr(OH)2/Ba(OH)2/Ra(OH)2OR(One of):Strontium/Barium/RadiumhydroxideIf name and formula given then bothmust be correctSrOH/ BaOH/RaOHJust Sr/ Ba/ RaMg(OH)2/MgOH/magnesiumhydroxide/Be(OH)2/BeOH/berylliumhydroxide1Number20 (e)(i) White ppt/solidALLOWWhite crystals (1)(BaSO4 is insoluble but) MgSO4 is(very) soluble / MgSO4 gives acolourless solution/ MgSO4 gives noprecipitateALLOWBaSO4 does not dissolveTE on first mark if it stated that aprecipitate formed even if colour iswrong/ missing(1)White ppt ofBaCl2 / MgCl2Extraobservations eg effervescence Magnesium is soluble / bariumis insolubleA precipitate of magnesiumsulfate formsand thendissolvesJust “MgSO4 is more soluble /less insoluble” Reference to solubility of chloridesThere would beno reaction2QuestionNumberAcceptable Answers Reject Mark20(e)(ii) Barium sulfate is not absorbed/ isinsolubleIGNOREComments on X-raysBarium sulfate is not digestedBarium sulfate is unreactive/ doesnot react with stomach acidsReferences to toxicity.Just ‘Barium’ 1QuestionNumberAcceptable Answers Reject Mark20 (f) First mark:(Increase) concentration of HCl(1)Second markMore particles/ moles of (HCl) in thesame volumeOR more (frequent/ successful )collisionsAllow second mark only if factor isconcentration (1)-------------------------------Any two from three of the followingfor third and fourth marks:Reduce particle size / use powder(instead of lumps)/ use finely divided(solid) (1)(Increases) surface area (1)more (frequent/ successful ) collisions(1)ALLOWReverse arguments Increase concentration of CaCO3 /HCl and CaCO3 /reactantsIncrease kinetic energy ofparticlesIncrease kinetic energy ofparticles4QuestionAcceptable Answers Reject MarkNumber1 20(g) Pressure only affects gaseous reactions/there are no gaseous reactants (orproducts) /there is no significant volumechange/ liquids are incompressibleALLOWpressure doesn’t affect solids/ solutionsNote: there are many possible correctways of expressing the idea thatpressure only affects rate of reactionsinvolving gases.IGNORENumber of moles in reaction doesn’tchangeTOTAL FOR Q20 = 20 MARKSTOTAL FOR SECTION B = 38 MARKSSection CQuestionNumberAcceptable Answers Reject Mark 21 (a) Primary (1)Part of the molecule whichdetermines how it will react / atom or group responsible for its reactions / group where chemical reactions occur/ part of the molecule responsible for its (chemical) propertiesALLOWThe part of the molecule which reacts / Group responsible for its characteristics (1)IGNOREGroup which determines how the molecule behaves Molecule responsible for reactions2QuestionNumberAcceptable Answers Reject Mark21 (b) C20H30OCorrect number of carbons (1)Rest of formula correct (stand alonemark, even if C incorrect) (1)Note: C20H29OH scores first markonlyIgnore working (structural formula)if shown as long as a molecularformula is given Juststructuralformula2QuestionNumberAcceptable Answers Reject Mark21(c)(i) Reflux apparatus produces carboxylic/ retinoicacidORcompletely oxidizes the alcohol(1)Convert to distillationALLOWuse condenser in horizontal position/description of distillation/ sketch of distillationapparatus (1)Oxidizing agent should be limiting/not inexcess/remove aldehyde as it is formed/ removebefore further oxidation (1)ALLOWUse excess alcohol‘Product’ for ‘aldehyde’Oxidizes to aketoneFractionaldistillationJust ‘thecollection ofaldehyde’3QuestionNumberAcceptable Answers Reject Mark21(c)(ii) Cr2O72-(aq)+14H+(aq)+ 6e-→2Cr3+(aq)+7H2O(l)+6 +3Orange GreenOne mark for the correct numbers of hydrogens(1)One mark for the correct numbers of chromiumsand electrons (1)One mark for each oxidation number with sign.If sign is missing penalise once onlyALLOW6+ , 3+ (2)One mark for both colours (1)Any othercolour withorange/Green-blue5Number21(c)(iii) (Retinal) (strong) absorption at1740-1720 (due to C=O bond)OR(Retinal) (weak) absorption at2900–2820/ 2775–2700 (due to C-Hbond)ALLOWWavenumber/ peak/ stretch for“absorption” (1)No absorption at 3750–3200/absorption at 3750-3200 shows notall retinol converted (1)Ignore comments on absorptions at3300-2500Absorption at1725-17001700-16802Number21(c)(iv)Any one of the following:ALLOW the following circles in retin ol Any additional area circled Circlesincluding anyC atom other than those ofthe doublebond circledon the mark scheme1Number21(c)(v) Round the carbon there arethree areas with electrons / 3 regionsof electron density/ 3 areas ofelectron densityALLOWThree bond pairs IF answer says thatdouble bond can be treated as onebond (1)Electron pairsrepel/ go to maximum separation/goto minimum repulsion (1)ALLOWBonds repelThe answer must clearly refer toelectrons/ bonds/ bonding pairs atsome point to score these marks.Trigonal planarALLOWTriangular planar (1)Round thecarbon there are3 bondsC with a lonepairatoms repelmaximumrepulsion/minimumseparation3QuestionNumberAcceptable Answers Reject Mark21 (d)Accept any orientation of =O and –OH andlength of bonds.Allow the OH displayed COOH addedto finalsingle bond OOH added1Number21 (e) Observation and precaution marks aredependent on correct reagent.EITHERReagentPCl5 / phosphorus((V)) chloride /phosphorus pentachlorideALLOWPhosphoric(V) chloride (1)ObservationSteamy/misty/white fumes (1)IGNORETests on steamy fumes eg litmusPrecautionUse of fume cupboard (1)IGNOREneed for safety goggles and lab coats. Incorrect reasons given for use of fume cupboard.Need for dry equipmentUse of gloves OR ALLOWReagentSodium/ Na (1) ObservationFizzing/Bubbles (1)IGNOREsodium dissolvesPrecautionHandle with gloves/tweezers (1) IGNOREnaked flamesneed for dry equipmentneed for safety goggles and lab coats. Whitesmoke/solid Dense white fumesGas mask3TOTAL FOR SECTION C (Question 21) = 22 MARKSTOTAL FOR PAPER = 80 MARKSAppendix A:Question 19ai: Additional Guidance.Pearson Education Limited. Registered company number 872828 with its registered office at Edinburgh Gate, Harlow, Essex CM20 2JE。

美国麻省理工学院化学工程专业介绍学校名称：美国麻省理工学院(剑桥)MassachusettsInstituteofTechnology(Cambridge)所在位置：美国，77MassachusettsAvenueCambridge,MA02139-4307(617)253-1000创建时间：1861 QS排名：2 USNEWS排名：5 学费：40732录取率：0.1申请美国留学的学生越来越多，那么美国麻省理工学院的化学工程专业怎么样呢?这是很多移民人士比较感兴趣的问题。

和出国移民网一起来看看吧!下面是小编整理的相关资讯，欢迎阅读。

美国麻省理工学院化学工程专业简介麻省理工学院的化学工程专业历史起源于19世纪晚期。

1888年，麻省理工学院化学教授LewisM.Norton创造了化学工程课程。

1891年，麻省理工学院化学工程学院成为第一个授予化学工程学士学位的地方。

1898年弗兰克·索普教授出版的工业化学概况，被认为是化学工程的第一本教科书。

1907年，麻省理工学院成为第一所授予化学工程专业博士学位的学校。

从那时起，麻省理工学院化学工程系领导全美化学工程的发展。

麻省理工学院化学工程专业基本申请要求学费$46,400申请截止日期12月1日TOEFL要求100GPA要求无可申请学期秋季IELTS要求7.0GRE要求要求GRESubject自愿麻省理工学院化学工程专业课程介绍麻省理工学院化学工程专业理科硕士学科的学生需要完成30学分的课程，学生可以选择主题方向或者是报告方向。

在主题方向的选择，要求该专业的学生需要完成24个学分的授课课程和6个学分的主题，其主题要求基于学生所直接研究表现。

在报告方向的选择，要求该专业的学生需要完成27个学分的授课课程和2个学分的报告，该报告要求根据文献回顾或设计表现的项目。

麻省理工学院化学工程专业前置课程·化学工程中的数字方法(NumericalMethodsinChemicalEngineering10.34)·化学工程热力学(ChemicalEngineeringThermodynamics10.40)·运输现象分析(AnalysisofTransportPhenomena10.50)·化学反应工程(ChemicalReactorEngineering10.65)麻省理工学院化学工程专业设置化学工程系有以下研究领域，分别是：·热力学与分子计算(ThermodynamicsandMolecularComputations)·催化剂与反应工程(CatalysisandReaction Engineering)·系统设计与工程(Systems DesignandEngineering)·运输过程(Transport Processes)·生物工程(Biological Engineering)·材料(Materials)·聚合物(Polymers)·表面与结构(SurfacesandStructures)·能源与环境工程(EnergyandEnvironmentalEngineering)麻省理工学院化学工程专业就业情况CollegeFactual的研究数据显示：麻省理工学院化学工程专业毕业生的平均年薪起薪为80,000美元，在职业生涯中期的薪资大约年薪为111,000美元。

化学选择性必修二实验计划英文回答：Chemistry Elective II Experiment Plan.Experiment 1: Determination of the Activation Energy of a Chemical Reaction.Objective: To determine the activation energy of a chemical reaction using the Arrhenius equation.Materials: Reactants, catalyst, thermometer, stopwatch, graduated cylinder, pipettes.Procedure:Prepare a series of solutions with different concentrations of the reactants.Add a catalyst to each solution.Measure the temperature of each solution and start the stopwatch.Monitor the temperature and record the time taken for the reaction to complete.Plot a graph of ln(rate) vs. 1/T and determine the slope of the line.Use the slope of the line to calculate the activation energy (Ea) using the Arrhenius equation:ln(rate) = -Ea/RT + ln(A)。

Experiment 2: Synthesis and Characterization of a Coordination Complex.Objective: To synthesize and characterize a coordination complex using spectroscopic techniques.Materials: Metal salt, ligand, solvent, spectrophotometer, IR spectrophotometer.Procedure:Prepare a solution of the metal salt and the ligand in a solvent.Heat the solution to reflux and allow the reaction to proceed for a specified time.Filter the reaction mixture and isolate the coordination complex.Characterize the coordination complex using UV-Vis spectrophotometry and IR spectroscopy.Determine the stoichiometry and geometry of the complex.Experiment 3: Determination of the Equilibrium Constant of a Chemical Reaction.Objective: To determine the equilibrium constant of achemical reaction using spectrophotometry.Materials: Reactants, solvent, spectrophotometer, cuvettes.Procedure:Prepare a series of solutions with different concentrations of the reactants at equilibrium.Measure the absorbance of each solution at a specific wavelength.Plot a graph of absorbance vs. concentration and determine the slope of the line.Use the slope of the line to calculate the equilibrium constant (K) using the Beer-Lambert law: A = εbc.中文回答：化学选择性必修二实验计划。

261区域治理MARKET作者简介：邱 瑾，生于1996年，江西师范大学研究生，研究方向为心理统计与测量。

认知诊断中的Q 矩阵简述江西师范大学心理学院 邱瑾摘要：作为新一代的心理测量理论，在教育测量领域认知诊断受到越来越多的青睐。

它不仅能在细粒度的层面上，评估个体在学科能力上的知识掌握状态，而且可以根据评估结果，给教师提供个体接下来的发展学习的道路。

在运用认知诊断理论作认知诊断评估的过程中，Q矩阵起着至关重要的作用。

关键词：认知诊断；Q矩阵；知识状态中图出版号：B842.1文献标识码：A文章编号：2096-4595（2020）28-0261-0001认知诊断是一项通过评估被试者的认知技能或特定知识（属性）集合的掌握情况的技术。

正如Tasuka 所说，它至少包含“Q 矩阵理论”和“诊断分类”两大部分。

在目前的认知诊断的领域中，有相当多的研究正把热点集中于Q 矩阵的修正和估计研究上。

这一研究热点不仅仅只存在于Q 矩阵修正方法开发研究、Q 矩阵估计方法开发研究，国内同样还存在着对Q 矩阵相关研究的综述上。

例如，王晓军，丁树良和罗芬（2019）作了Q 矩阵的综述，存在层级属性关系的Q 矩阵的算法、作用，刘永和涂冬波（2015）讨论的是根据被试反应估计Q 矩阵的6种方法。

一、认知诊断的目的在认知诊断的过程中，Q 矩阵是必不可少的一部分。

在认识Q 矩阵的概念和作用之前，我们应该了解认知诊断的目的。

Leighton 和Gierl(2007)指出，认知诊断致力于评估受测者的特定知识结构和加工技能的掌握情况，它是基于个人的认知过程上的诊断。

在认知过程中加工技能也可称之为属性，认知诊断评估最后会给出受测者在多个属性上的属性掌握状态用以表示被试的知识状态。

关键的问题是，如何通过被试作答项目的反应来判断被试的属性掌握状态？重点在于Q 矩阵的建立。

Q 矩阵理论主要是确定测验项目所测的间接观察的认知属性，并把它转化为可直接监测的理想反应模式，将被试在“黑箱子”里的认知状态与在项目上直观的作答反应联系起来，进而为了解并推测被试的认知状态提供基础。

basic solution化学英文回答：What is a basic solution?A basic solution is a solution that has a pH greater than 7.0. This means that the solution contains more hydroxide ions (OH-) than hydrogen ions (H+). Basic solutions are also known as alkaline solutions.What are the properties of basic solutions?Basic solutions have a number of characteristic properties, including:They are slippery to the touch.They taste bitter.They turn red litmus paper blue.They react with acids to form salts and water.What are the uses of basic solutions?Basic solutions are used in a variety of applications, including:Cleaning agents: Basic solutions are often used as cleaning agents because they can dissolve grease and dirt.Deodorants: Basic solutions can be used as deodorants because they can neutralize acids that cause body odor.Medicines: Basic solutions are used in a number of medicines, such as antacids and cough syrups.How can you make a basic solution?There are a number of ways to make a basic solution, including:Dissolving a base in water: The most common way to make a basic solution is to dissolve a base in water. Some common bases include sodium hydroxide (NaOH), potassium hydroxide (KOH), and calcium hydroxide (Ca(OH)2).Mixing an acid and a base: You can also make a basic solution by mixing an acid and a base. When an acid and a base react, they form a salt and water. The salt will be basic if the base is stronger than the acid.Safety precautions.Basic solutions can be harmful if they are not handled properly. It is important to wear gloves and eye protection when working with basic solutions. Basic solutions should also be stored in a safe place away from children and pets.中文回答：什么是碱性溶液？碱性溶液是pH值大于7.0的溶液。

官方SAT2化学真题解析Subj...Chemistry SAT Subject Tests?Answer Explanations to Practice Questions from Getting Ready for the SAT Subject TestsVisit the SAT? student website toget more practice and study tips forthe Subject Test in Chemistry.SAT? Subject Test in ChemistryIn this document, you will find detailed answer explanations to all of the chemistry practice questions from Getting Ready for the SAT Subject Tests. By reviewing these answer explanations, you can familiarize yourself with the types of questions on the test and learn your strengths and weaknesses. The estimated difficulty level is based on a scale of 1 to 5, with 1 the easiest and 5 the most difficult.To find out more about the SAT Subject Tests, visit us at /doc/b17639eaaeaad1f346933fac.html.1. Difficulty: 2Choice (C) is correct. To answer this question, you mustrecognize which of the choices above are acid solutions.Only choices (A) and (C) satisfy this requirement. Choice(B) refers to a neutral salt solution, choice (D) is a solutionof an alcohol, and choice (E) is a basic solution. Choices(A) and (C) are both acidic solutions, but choice (A) is astrong acid that is completely ionized in aqueous solution, whereas choice (C) is only partially ionized in aqueoussolution. Since the concentrations of all the solutions are the same, you do not need to consider this factor. The hydrogen ion concentration of a 0.1 molar acetic acid solution isconsiderably smaller than 0.1 molar. The hydrogen ionconcentration in choice (A) is equal to 0.1 molar. Thus, the correct choice is choice (C), a weakly acidic solution.2. Difficulty: 3Choice (E) is correct. To answer this question, you needto understand the pH scale, which is a measure of thehydrogen ion concentration in solution and is defined aspH = -log [H+]. The higher the pH, the lower the hydrogen ion concentration and the more basic the solution. Among the choices given above, choice (E) is the most basic solution.3. Difficulty: 4Choice (A) is correct. To answer this question, you needto know that acids react with bases to form salts andwater. Since the question refers to equal volumes of eachsolution, assume 1 liter of each solution is available.Barium hydroxide solution is a strong base (i.e., it iscompletely ionized in water), and 1 liter of 0.05 M Ba(OH)2 provides 0.1 mole of OH- ions in solution. When 1 liter of this solution is added to 1 liter of either 0.1 M NaCl,0.1 M CH3OH or 0.1 M KOH, no reactions occur and theresulting solutions remain basic; that is, the pH will begreater than 7 in each case. When 0.1 mole of OH- ionsreacts with 0.1 mole of acetic acid, the resulting solutionwill also be basic and have a pH greater than 7 becauseacetic acid is a weak acid (i.e., it is incompletely ionized inwater). The acetic acid reacts with the OH- ions as follows: HC2H3O2 + OH- C2H3O2- + H2OThe acetate ion produced is a strong base, which hydrolyzes in water to yield a solution containing more OH- ions than H+ ions. When 1 liter of 0.05 M Ba(OH)2 reacts with1 liter of 0.1 M HCl, there is a reaction between 0.1 mole ofOH- ions and 0.1 mole of H+ to form 0.1 mole of H2O. The resulting solution contains Ba2+ ions and Cl- ions and equal concentrations of OH- and H+ ions. The solution formed is neutral, and the pH is 7; therefore choice (A) is the correct answer.4. Difficulty: 3Choice (A) is correct. The chemical formula of sodiumacetate is NaC2H3O2. The sodium ion is Na+, and theacetate ion is C2H3O2-. The Na+ ion has the form X+.5. Difficulty: 1Choice (C) is correct. The chemical formula of aluminumoxide is Al2O3. The aluminum ion is Al3+, and the oxide ion is O2-. The Al3+ ion has the form X3+.6. Difficulty: 2Choice (A) is correct. The chemical formula of potassiumphosphate is K3PO4. The potassium ion is K+, and thephosphate ion is PO43-. The K+ ion has the form X+, andthe phosphate ion has the form XO43- ; therefore the correct answer is choice (A).7. Difficulty: 3Choice (C) is correct. The highest principal quantum number in this electron configuration is 3 (valence electrons 3s2 3p4), so the element is in the third period of the periodic table. The atom has two s and four p valence electrons, so it is in theoxygen group. The atom is therefore an atom of sulfur.8. Difficulty: 3Choice (A) is correct. The Ca2+ ion is a Ca atom that haslost two electrons. Ca has an atomic number of 20 and has20 electrons, so Ca2+ must have 18 electrons. The neutralatom with 18 electrons (and 18 protons) is Ar. Note thatAr is two elements before Ca in the periodic table.9. Difficulty: 2Choice (E) is correct. The element with the lowest atomicnumber that has any electrons in an f orbital is cerium(atomic number 58), which has the electron configuration[Xe] 4f 1 5d1 6s2. All elements with an atomic numberequal to or greater than 58 have ground-state atoms withelectrons in f orbitals. Uranium has an atomic number of92; therefore, the correct answer is (E).10. Difficulty: 2Choice (A) is correct. Argon is a noble gas, and noble gases are relatively unreactive.101. Difficulty: 3Both statements are true, and statement II gives the reason that statement I is correct. The correct answer is therefore true, true, correct explanation.102. Difficulty: 3It is true that diamond melts at a very high temperature(over 3,500°C). Substances with ionic bonding do have high melting points, but the bonding in diamond is network covalent, not ionic. (Note that unless both statements aretrue, it is not necessary to determine whether the secondstatement is a correct explanation of the first statement.) 103. Difficulty: 3Ionization energy depends on effective nuclear chargeand the distance of the electron from the nucleus. Outerelectrons are partially shielded from the nucleus by innerelectrons, so the effective nuclear charge is about the same for atoms of elements in the same group of the periodictable. Potassium (K) and lithium (Li) are in the samegroup of the periodic table, but the lithium atom has fewer occupied shells and a smaller atomic radius. The outermost electron in Li is in a shell that is close to the nucleus, and the outermost electron in K is in a shell that is relatively far from the nucleus. Therefore, there is less attraction between the outermost electron in a K atom and its nucleus thanbetween the outermost electron in a Li atom and its nucleus, and it is easier to remove an electron from a K atom, resulting in a lower first ionization energy for K than for Li.It is true that K (atomic number 19) has more protons inits nucleus than does Li (atomic number 3), but this is notthe reason for the relative ionization energies. (Note, forexample, that Ca has more protons in its nucleus than does K, but Ca has a higher first ionization energy than does K.) The correct answer is true, true, not a correct explanation. 104. Difficulty: 4In the activity series, Zn is relatively easy to oxidize to Zn2+, while Cu is relatively inactive. Therefore, if Zn metal were placed in a solution containing Cu2+ ions, Zn would beoxidized to Zn2+ ions, and Cu2+ would be reduced to Cumetal. Both statements are true, and statement II gives the reason that statement I is correct. The correct answer istherefore true, true, correct explanation.105. Difficulty: 5When a system at equilibrium is disturbed, the systemwill shift in a way that partially offsets the effect of thedisturbance (LeChatelier’s principle). Thus, when HC2H3O2 is added to the equilibrium mixture, the equilibriumwill shift to the right. This increases the concentration ofC2H3O2- and H3O+. Statement I is therefore false. Changes in the concentrations of reactants and products do not affect thevalue of the equilibrium constant; if the temperature does not change, the value of the equilibrium constantdoes not change. Statement II is therefore false. The correct answer is false, false.11. Difficulty: 3Choice (C) is correct. This is a question that concernsthe concentration of a diluted solution. One way to solvethe problem is through the use of ratios. In this question,a solution of nitric acid is diluted 10-fold; therefore, theconcentration of the solution will decrease by a factor of 10, that is, from 0.100 molar to 0.010 molar. Alternatively, you could calculate the number of moles of H+ ions present and divide this value by 0.50 liter: (0.100 × 0.050)/0.5 = M of the diluted solution.12. Difficulty: 2Choice (D) is correct. This question pertains to thebalancing of chemical equations. To answer this questioncorrectly, you need to recognize that both mass and charge must be conserved in any chemical equation. With this in mind, the chemical equation is correctly written as2 Cu2+(aq) + 4 I-(aq) → 2 CuI(s) + I2(s)The coefficient for I-(aq) is 4.13. Difficulty: 4Choice (C) is correct. This is a laboratory-orientedquestion pertaining to the measurement of gas pressures. It demands higher-level analytical skills that involve drawing conclusions from results obtained in an experiment. To answer this question correctly, you must first understandthat, in an open type of manometer, the air exerts pressure on the column of liquid in the open side of the U-tube, andthe gas being studied exerts pressure on the other side of the U-tube. It is clear, then, that statement I is true sincethe data given show that the manometer is open-ended,and its right side is exposed to the atmosphere. Statement II is also true because the level of liquid mercury is higherin the right side, which is exposed to the atmosphere, than in the left side, which is exposed to the gas. Thus the gaspressure is greater than atmospheric pressure. StatementIII is not correct because the pressure of the gas in thebulb, expressed in millimeters of mercury, is equal to thedifference in height, h, of the two mercury levels, plus theatmospheric pressure. Thus only statements I and II aretrue, and the correct answer is choice (C).14. Difficulty: 3Choice (B) is correct. This is a question on states ofmatter. Y ou must convert the description of the physicalphenomenon given in the question to graphical form.When a liquid is cooled slowly, its temperature will decrease with time. Thus the first portion of a graph depicting this phenomenon must show a decrease when temperature isplotted against time. When a pure liquid substance reaches its fusion (melting) point, continued cooling will release heat with time as the substance solidifies. During thisperiod, there is no drop in temperature. After the substance has completely solidified, further cooling will cause an additional drop in temperature. The only graph shown that accurately depicts the events described is choice (B), which is the correct answer.15. Difficulty: 3Choice (A) is correct. This is a question on chemicalbonding that requires you to apply the principles ofmolecular bonding. Each of the molecules given is correctly paired with the term describing its molecular geometry except choice (A). The geometry of PF3 is not trigonalplanar but trigonal pyramidal because this geometrycorresponds to a maximum possible separation of theelectron pairs around the central atom, phosphorus, andtherefore yields the most stable configuration; the centralatom of the molecule is surrounded by the three singlebonds and one unshared electron pair. Thus, the correctanswer is choice (A). Note that this is the type of questionthat asks you to identify the one solution to the problemthat is inappropriate.16. Difficulty: 2Choice (C) is correct. This question tests your ability tobalance chemical equations. The stoichiometry of thecorrectly balanced equation indicates that 2 moles of SO2(g) are needed to react completely with 1 mole of O2(g) to form2 moles of SO3.17. Difficulty: 3Choice (B) is correct. This is a question on stoichiometrythat tests the important skill of scientific reasoning basedon experimental evidence. The question indicates that 100 percent of the composition of the compound analyzed can be accounted for with the elements hydrogen and carbon.Thus, this compound is a hydrocarbon and choice (A)is a correct statement. It is not the correct answer to thequestion, however, because you can deduce more specific conclusions about this compound from the informationgiven. The relative percentage composition providesevidence that the atomic ratio of carbon to hydrogenin the compound must be 86/12 : 14/1.0, or about 1 : 2.Therefore, you can conclude that the empirical formula for the compound is CH2. Thus choice (B) is a better answer than choice (A). Since you do not know the total numberof moles of the compound used for analysis, you cannotcalculate the molar mass or derive the molecular formulafor this compound. Therefore choices (C) and (D) cannotbe determined from the information given and thus are not correct answers to the question. It is known, however, that a substance with an empirical formula of CH2 cannot have a triple bond. Therefore choice (E) is incorrect.18. Difficulty: 2Choice (D) is correct. The molar mass of C3H8 is 44.0 g/mol.According to the equation, four moles of water are formed for each mole of propane combusted. The molar massof water is 18.0 g/mol, so the mass of water formed is18.0 g × 4 = 72.0 g.19. Difficulty: 1Choice (D) is correct. Each mole of KHSO4 contains fourmoles of oxygen atoms, so 0.50 mol of KHSO4 containstwo moles of oxygen atoms. One mole is 6.0 × 1023, and2 (6.0 × 1023) = 12 × 1023 = 1.2 × 1024.20. Difficulty: 3Choice (E) is correct. Air contains mostly N2 (molar mass28 g/mol) and O2 (molar mass 32 g/mol). The molar mass ofcarbon dioxide is 44 g/mol, so carbon dioxide is more dense than air. The other statements are true and are not correct choices.21. Difficulty: 3Choice (D) is correct. Going down a group of the periodictable, atomic radius and atomic mass increase. Becauseeffective nuclear charge is about the same within a groupand radius increases going down a group, ionization energy decreases going down a group.22. Difficulty: 4Choice (E) is correct. In aqueous solution, HI can donate aproton and form I-, NH4+ can donate a proton to form NH3, HCO3- can donate a proton to form CO32-, and H2S can donate a proton to form HS-. NH3 does not donate a proton in aqueous solution to form NH2-; therefore, choice (E) is the correct answer.2011 The College Board. College Board, achieve more, SAT and the acorn logo are registered trademarks of the College Board. SAT Subject Tests is a trademark owned by the College Board.。