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牙膏中的摩擦剂为碳酸钙（CaCO3），通过计算回答下列问题．（1）CaCO3的相对分子质为 ；（2）CaCO3中碳元素与氧元素的质量比为 ；（3）CaCO3中钙元素的质量分数为 ．
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轻质碳酸钙广泛应用于橡胶塑料油漆水性涂料以及造纸等行业日常生活中的牙膏也常用它作摩擦剂目前轻质碳酸钙
某学生为了测定一种以碳酸钙为摩擦剂的牙膏中碳酸钙的含量用烧杯称取这种牙膏膏体100.0克向烧杯中逐渐
已知普通补钙剂的主要成分为碳酸钙化学式为CaCO3试计算碳酸钙中钙元素的质量分数若补钙剂中含碳酸钙的
生白云石的主要化学成份是碳酸钙CaCO3和碳酸镁MgCO3
牙膏中常用碳酸钙二氧化硅等物质作为摩擦剂某同学对牙膏中摩擦剂碳酸钙的含量进行探究【实验原理】测定C.
饲料级轻质碳酸钙以干基计算质量标准中规定CaCO3含量应大于或等于
90.0%
95.0%
98.0%
39.2%
碳酸钙CaCO3是某种补钙剂的成分之一请计算1碳酸钙的相对分子质量=2碳酸钙中钙元素的质量分数=.
测定牙膏中摩擦剂碳酸钙的含量 某同学为测定一种以碳酸钙为摩擦剂的牙膏中碳酸钙CaCO3的含量用烧
轻质碳酸钙广泛应用于橡胶塑料油漆水性涂料以及造纸等行业日常生活中的牙膏也常用它作摩擦剂目前轻质碳酸钙
碳酸钙CaCO3是某种补钙剂的成分之一请计算1碳酸钙的相对分子质量=12碳酸钙中钙元素的质量分数=.
牙膏中常用碳酸钙二氧化硅等物质作为摩擦剂某同学对牙膏中摩擦剂碳酸钙的含量进行探究【实验原理】测定C.
某研究性学习小组的同学通过课外学习了解到某品牌牙膏中含有摩擦剂湿润剂表面活性剂黏合剂香料甜味剂等成分
碳酸钙是牙膏中常用的摩擦剂可用石灰石作原料制得某牙膏厂现有一批石灰石样品为探究所含碳酸钙的质量高温煅
石灰石粉的化学名称是碳酸钙分子式为CaCO3
小远通过查阅资料知道了牙膏的主要成分他将一定比例的碳酸钙粉末和食盐倒入小烧杯中然后加入适量的甘油保湿
在炉前喷钙脱硫工艺中碳酸钙CaCO3在炉膛温度900-1250℃的区域内受热分解成氧化钙CaO和二氧
小玲通过查阅资料知道了牙膏的主要成分她将一定比例的碳酸钙粉末和食盐倒入小烧杯中然后加人适量的甘油保湿
已知SiO2不与稀盐酸反应牙膏中的摩擦剂约占牙膏成分的50%主要用于增强牙膏对牙齿的摩擦和去污牙膏摩
牙膏中常用碳酸钙二氧化硅等物质作为摩擦剂．某同学对牙膏中摩擦剂碳酸钙的含量进行测定取某品牌牙膏20
冶金石灰的主要化学成分是碳酸钙CaCO3
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FreedomandResponsibility Freedom'schallengeintheDigitalAgeisaserioustopic.Wearefacingtodayastrangenewworldandweareallwonderingwhatwearegoingtodowithit. Some2500yearsagoGreecediscoveredfreedom.Beforethattherewasnofreedom.Thereweregreatcivilizationssplendidempiresbutnofreedomanywhere.EgyptandBabylonwerebothtyranniesoneverypowerfulmanrulingoverhelplessmasses. InGreeceinAthens雅典alittlecityinalittlecountrytherewerenohelplessmasses.AndAthenianswillinglyobeyedthewrittenlawswhichtheythemselvespassedandtheunwrittenwhichmustbeobeyediffreemenlivetogether.Theymustshoweachotherkindnessandpityandthemanyqualitieswithoutwhichlifewouldbeverypainfulunlessonechosetolivealoneinthedesert.TheAtheniansneverthoughtthatamanwasfreeifhecoulddowhathewanted.Amanwasfreeifhewasself﹣controlled.Tomakeyourselfobeywhatyouapprovedwasfreedom.Theyweresavedfromlookingattheirlivesastheirownprivateaffair.EachonefeltresponsibleforthewelfareofAthensnotbecauseitwasforcedonhimfromtheoutsidebutbecausethecitywashisprideandhissafety.Theessentialbeliefofthefirstfreegovernmentintheworldwaslibertyforallmenwhocouldcontrolthemselvesandwouldtakeresponsibilityforthestate. Butdiscoveringfreedomisnotlikediscoveringcomputers.Itcannotbediscoveredonceforall.Ifpeopledonotprizeitandworkforititwillgo.Constantwatchisitsprice.Athenschanged.Itwasachangethattookplacewithoutbeingnoticedthoughitwasoftheextremeimportanceaspiritualchangewhichaffectedthewholestate.IthadbeentheAtheniansprideandjoytogivetotheircity.Thattheycouldgetmaterialbenefitsfromherneverenteredtheirminds.Therehadtobeacompletechangeofattitudebeforetheycouldlookatthecityasanemployerwhopaidhercitizensfordoingherwork.Nowinsteadofmengivingtothestatethestatewastogivetothem.Whatthepeoplewantedwasagovernmentwhichwouldprovideacomfortablelifeforthemandwiththisastheprimaryobjectideasoffreedomandself﹣relianceandresponsibilitywereneglectedtothepointofdisappearing.Athenswasmoreandmorelookedonasacooperativebusinesspossessedofgreatwealthinwhichallcitizenshadarighttoshare. Athensreachedthepointwhenthefreedomshereallywantedwasfreedomfromresponsibility.Therecouldbeonlyoneresult.Ifmeninsistedonbeingfreefromtheburdenofself﹣dependenceandresponsibilityforthecommongoodtheywouldceasetobefree.Responsibilityisthepriceeverymanmustpayforfreedom.Itistobehadonnootherterms.AthenstheAthensofAncientGreecerefusedresponsibilityshereachedtheendoffreedomandwasnevertohaveitagain. ButtheexcellentbecomesthepermanentAristotlesaid.Athenslostfreedomforeverbutfreedomwasnotlostforeverfortheworld.AgreatAmericanJamesMadisonreferredtoThecapacity能力ofmankindforself﹣government.NodoubthehadnotanideathathewasspeakingGreek.Athenswasnotinthefarthestbackgroundofhismindbutoncemanhasagreatandgoodideaitisnevercompletelylost.TheDigitalAgecannotdestroyit.Somehowinthisorthatman'sthoughtsuchanidealivesthoughunconsideredbytheworldofaction.Onecanneverbesurethatitisnotonthepointofbreakingoutintoactiononlysurethatitwilldososometime. 65.WhatdoestheunderlinedwordtyranniesinParagraph2referto? A.Countrieswheretheirpeopleneedhelp. B.Powerfulstateswithhighercivilization. C.Splendidempireswherepeopleenjoyfreedom. D.Governmentsruledwithabsolutepower. 66.Peoplebelievinginfreedomarethosewho. A.regardtheirlifeastheirownbusiness B.seekgainsastheirprimaryobject C.behavewithinthelawsandvaluesystems D.treatotherswithkindnessandpity 67.WhatchangeinattitudetookplaceinAthens? A.TheAtheniansrefusedtotaketheirresponsibility. B.TheAtheniansnolongertookprideinthecity. C.TheAtheniansbenefitedspirituallyfromthegovernment. D.TheAthenianslookedonthegovernmentasabusiness. 68.WhatdoesthesentenceTherecouldbeonlyoneresult.inParagraph5mean? A.Athenswouldcontinuetobefree. B.Athenswouldceasetohavefreedom. C.Freedomwouldcomefromresponsibility. D.FreedomwouldstopAthensfromself﹣dependence. 69.WhydoestheauthorrefertoAristotleandMadison? A.Theauthorishopefulaboutfreedom. B.Theauthoriscautiousaboutself﹣government. C.TheauthorisskepticalofGreekcivilization. D.Theauthorisproudofman'scapacity. 70.Whatistheauthor'sunderstandingoffreedom? A.Freedomcanbemorepopularinthedigitalage. B.Freedommaycometoanendinthedigitalage. C.Freedomshouldhavepriorityoverresponsibility. D.Freedomneedstobeguaranteedbyresponsibility.
下列推理不正确的是 ①同种分子构成的物质一定属于纯净物 ②只含一种元素的物质一定是单质 ③质子数相同的微粒一定是同种元素 ④含有氧元素的化合物一定是氧化物 ⑤最外层电子数相等的原子化学性质一定相似 ⑥化学反应前后原子的个数和种类一定不改变 ⑦同种物质中同种元素一定显相同价态．
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厨师在厨房炒菜时加了料后再加醋就让菜肴变得香美可口这其实隐藏了一个化学的小秘密醋中的乙酸与料酒中的乙醇反应生成了有香味的乙酸乙酯下表中是几种常见的酯请完成下列问题 1甲酸甲酯中碳元素氢元素氟元素的质量比为其中氢元素的质量分数为保留0.1% 2比较归纳是学习的重要方法根据表推测X的化学式是 3丙酸丙酯中氧元素的质量分数填“大于”“小于”或“等于”丁酸丁酯中氧元素的质量分数 4若菜肴中的乙酸乙酯在人体内代谢时其中的碳元素完全部转化为CO2则44mg的乙酸乙酯完全代谢产生的CO2的质量为多少请写出计算过程
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请阅读下面文字及图表并按照要求用英语写一篇150词左右的文章. [写作内容] 1.用约30个单词概述上述信息的主要内容 2.结合上述信息简要分析导致交通问题的主要原因 3.根据你的分析从社会规范rulesandregulations和个人行为两方面谈谈你得到的启示不 少于两点. [写作要求] 1.写作过程中不能直接引用原文语句 2.作文中不能出现真实姓名和学校名称 3.不必写标题. [评分标准] 内容完整语言规范语篇连贯词数适当.
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IntheUnitedStatesaloneover100millioncell﹣phonesarethrownawayeachyear.Cell﹣phonesarepartofagrowingmountainofelectronicwastelikecomputersandpersonaldigitalassistants.Theelectronicwastestreamisincreasingthreetimesfasterthantraditionalgarbageasawhole. Electronicdevicescontainvaluablemetalssuchasgoldandsilver.ASwissstudyreportedthatwhiletheweightofelectronicgoodsrepresentedbypreciousmetalswasrelativelysmallincomparisontototalwastetheconcentration含量ofgoldandotherpreciousmetalswashigherinSo﹣callede﹣wastethaninnaturallyoccurringminerals. Electronicwastesalsocontainmanypoisonousmetals.Evenwhenthemachinesarerecycledandtheharmfulmetalsremovedtherecyclingprocessofteniscarriedoutinpoorcountriesinpracticallyuncontrolledwayswhichallowmanypoisonoussubstancestoescapeintotheenvironment. Creatingproductsoutofrawmaterialscreatesmuchmorewastematerialupto100timesmorethanthematerialcontainedinthefinishedproducts.Consideragainthecell﹣phoneandimaginetheminesthatproducedthosemetalsthefactoriesneededtomaketheboxandpackaging包装itcamein.Manywastesproducedintheproducingprocessareharmfulaswell. TheU.S.EnvironmentalProtectionAgencynotesthatmostwasteisdangerousinthattheproductiondistributionanduseofproducts﹣aswellasmanagementoftheresultingwaste﹣allresultingreenhousegasrelease.Individualscanreducetheircontributionbycreatinglesswasteatthestart﹣forinstancebuyingreusableproductsandrecycling. Inmanycountriestheconceptofextendedproducerresponsibilityisbeingconsideredorhasbeenputinplaceasanincentive动机forreducingwaste.Ifproducersarerequiredtotakebackpackagingtheyusetoselltheirproductswouldtheyreducethepackaginginthefirstplace? Governments'incentivetorequireproducerstotakeresponsibilityforthepackagingtheyproduceisusuallybasedonmoney.Whytheyaskshouldcitiesortownsberesponsibleforpayingtodealwiththebubblewrap气泡垫thatencasedyourtelevision? Fromthegovernments'pointofviewaprimarygoaloflawsrequiringextendedproducerresponsibilityistotransferboththecostsandthephysicalresponsibilityofwastemanagementfromthegovernmentandtax﹣payersbacktotheproducers. 58.BymentioningtheSwissstudytheauthorintendstotellusthat. A.theweightofe﹣goodsisrathersmall B.E﹣wastedeservestobemadegooduseof C.naturalmineralscontainmorepreciousmetals D.thepercentageofpreciousmetalsisheavyine﹣waste 59.Theresponsibilityofe﹣wastetreatmentshouldbeextended. A.fromproducerstogovernments B.fromgovernmentstoproducers C.fromindividualstodistributors D.fromdistributorstogovernments 60.Whatdoesthepassagemainlytalkabout? A.Theincreaseine﹣waste. B.Thecreationofe﹣waste. C.Theseriousnessofe﹣waste. D.Themanagementofe﹣waste.
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瘦素是由白色脂肪细胞分泌的一种蛋白质类激素科学家发现这种激素可以通过减少进食量促进产热来减轻哺乳动物的体重．为了研究该激素的调节机制科学家进行了系列实验． 1给健康的饥饿小鼠饲喂/注射瘦素后小鼠产热增加推测此时小鼠散热的机制是皮肤和分泌增强以维持体温的相对恒定． 2现有两类患肥胖症的小鼠B小鼠肥胖是瘦素基因缺陷所致A小鼠肥胖原因未知．科学家进行连体共生即通过手术使两只小鼠的血液循环贯通实验如表 根据实验结果推测在连体前与正常小鼠比较B小鼠体内瘦素的含量较低/一样/较高A小鼠肥胖的原因最可能是．为排除手术对实验结果的干扰可增设一组处理措施为的对照实验．
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我国自主研发的抗癌新药“西达本胺”已全球上市西达本胺的化学式为C22H19FN4O2下列关于西达本胺的说法正确的是
某种植物的花色有白蓝和紫三种颜色花色受两对等位基因Aa和Dd控制且两对基因分别位于两对同源染色体上．花色相关的色素遗传如图所示请回答 1控制花色的基因遵循定律判断的理由是． 2开蓝花植株的基因型为． 3现有花色基因型为AADDaaDD和aadd的三个纯合品种从中任意选出所需品种在最短时间内培育出大量能稳定遗传的蓝色品种写出培育流程要求写出遗传图解并配有简要的相关文字说明
镓是一种放在手心就会熔化的金属图①是镓元素在元素周期表中的信息图②是镓原子的结构示意图请回答 1镓原子位于元素周期表中第周期 2ABC三种微粒所属元素中与镓元素化学性质相似的是填“A”“B”或“C”则镓离子与B粒子形成的化合物的化学式为 3镓和C形成的化合物是由“分子”“原子”或“离子”直接构成 4D为某粒子的结构示意图其中当x﹣y＝8时该粒子的符号为．
近年来京津冀地区饱受沙尘暴之苦．因此保护生态环境大力开展植树种草防止沙漠化等是当前的紧要任务． 1在退耕还林还草过程中要生态工程的原理做到树种草种不能过于单一同时也要遵循生态工程的原理才不会出现“前面造林后面砍林”的现象． 2防止沙漠化最好种植耐旱性植物科研人员将获得的大肠杆菌中的海藻糖合成酶基因导入植物细胞中并获得有效表达增强了植物的耐旱性．获得的海藻糖合成酶基因可利用PCR技术扩增该技术反应体系中除含缓冲液引物和dNTP以外还应含有其中dNTP的作用是设计引物时要注意避免． 3如图为用探针检验某一转海藻糖合成酶基因抗旱植物基因型的原理相关基因用R和r表示． ①若被检植株发生A现象不发生BC现象则被检植物的基因型为． ②经检测抗旱基因已经导入烟草细胞但未检测出抗旱基因转录出的mRNA从构建基因表达载体的角度推测最可能的原因是．
下列有关实验操作与实验现象的叙述错误的是
Youthsporthasthepotentialtoaccomplishthreeimportantobjectivesinchildren'sdevelopment.Firstsportprogramscanprovideyouthwithopportunitiestobephysicallyactivewhichcanleadtoimprovedphysicalhealth.Secondyouthsportprogramshavelongbeenconsideredimportanttoyouth'spsychosocialdevelopmentprovidingopportunitiestolearnimportantlifeskillssuchascooperationdisciplineleadershipandself﹣control.Thirdyouthsportprogramsarecriticalforthelearningofmotorskillsthesemotorskillsserveasafoundationforfuturenationalsportstarsandrecreationaladultsportparticipants.Whencoachersdevelopactivitiesforyouthpracticesandwhensportorganizationsdesignyouth﹣sportprogramstheymustconsidertheimplicationofdeliberateplayanddeliberatepractice. ResearchfromTelama2006statesthatregularparticipationindeliberateplayordeliberatepracticeactivitiesduringchildhoodandyouthagesninetoeighteenincreasesthelikelihoodofparticipationinsportsduringadulthoodbysixtimesforbothmalesandfemales.Côté2002definesdeliberateplayactivitiesinsportasthosedesignedtomaximizeenjoyment.Theseactivitiesareregulatedbyflexiblerulesadaptedfromstandardizedsportrulesandaresetupbythechildrenorbyaninvolvedadult.Childrentypicallychangerulestofindapointwheretheirgameissimilartotheactualsportbutstillallowsforplayattheirlevel.Forexamplechildrenmaychangesoccerandbasketballrulestosuittheirneedsandenvironmente.g.inthestreet.onaplayingfieldorinsomeone'sbackyard.Wheninvolvedindeliberateplayactivitieschildrenarelessconcernedwiththeoutcomeoftheiroutcomeoftheirbehavior.whethertheywinorlosethanwiththebehavior.havingfun. OntheotherhandEricsson1993suggeststhatthemosteffectivelearningoccursthroughinvolvementinhighlystructuredactivitiesdefinedasdeliberatepractice.Deliberatepracticeactivitiesrequireeffortproducenoimmediaterewardsandaremotivatedbythegoalofimprovingperformanceratherthanthegoalofenjoyment.Whenindividualsareinvolvedindeliberateplaytheyexperimentwithdifferentcombinationsofbehaviorsbutnotnecessarilyinthemosteffectivewaytoimproveperformance.Incontrastwhenindividualsareinvolvedindeliberatepracticetheyexhibitbehavior.focusedonimprovingperformancebythemosteffectivemeansavailable.Forexamplethebackhandskillsintenniscouldbelearnedandimprovedovertimebyplayingmatchesorbycreatingfunpracticesituations.Howeverplayerscouldmoreeffectivelyimprovetheirbackhandperformancebypracticingdrillsthatmightbeconsideredlessenjoyable.Althoughdrillsareusedinmosteffectivemeansavailablepracticemightnotbethemostenjoyabletheymightbethemostrelevanttoimprovingperformance. NoteAnswerthequestionsorcompletethestatementsinNOMORETHANTENWORDS 78.Besidesthelearningofmotorskillswhataretheothertwoimportantobjectivesofyouthsport?. 79.Ifchildrenparticipateindeliberateplayordeliberatepracticeactivitiestheyaremorelikelyto. 80.Indeliberateplayactivitieswhatdochildrendotomaximizeenjoyment?. 81.Incontrasttodeliberateplaydeliberatepracticeisaimedat.
加压或降温可将氧气变成液氧下列说法正确的是
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