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一组数据1，7，8，5，4的中位数是a，则a的值是 ．
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一组数据577x的中位数与平均数相等则x的值为.
若一组数据34x58的平均数是4则该组数据的中位数是__________.
已知一组数据346788下列说法正确的是
众数是2
众数是8
中位数是6
中位数是7
下列说法正确的是
数据3，4，4，7，3的众数是4
数据0，1，2，5，a的中位数是2
一组数据的众数和中位数不可能相等
数据0，5，－7，－5，7的中位数和平均数都是0
现有一组数据2344555566778共有13个数据其样本中位数为
4
5
5.5
6
下列说法中正确的有1描述一组数据的平均数只有一个2描述一组数据的中位数只有一个3描述一组数据的众数只
1个
2个
3个
4个
一组数据456778的中位数和众数分别是.
7，7
7，6.5
5.5，7
6.5，7
一组数据34x68的平均数是5则这组数据的中位数是
4
5
6
7
一组数据456778的中位数和众数分别是
7，7
7，6.5
5.5，7
6.5，7
现有一组数据174386145其中位数为
3
5.5
6
下面说法①如果一组数据的众数是5那么这组数据中出现次数最多的数是5②如果一组数据的平均数是0那么这组
1
2
3
4
已知一组数据9988765则这组数据的中位数是
9；
8；
7；
6.
一组数据24568的中位数是.
已知一组数据34456747那么这组数据的
）中位数是5.5，众数是4 （
）中位数是5，平均数是5 （
）中位数是5，众数是4 （
）中位数是4.5，平均数是5
若一组数据34x58的平均数是4则该组数据的中位数是
一组数据357847的中位数是
一组数据18533的中位数是
3
3.5
4
5
一组数据556x778已知这组数据的平均数是6则这组数据的中位数是..
一组数据456778的中位数和众数分别是
7， 7
7， 6.5
5.5， 7
6.5， 7
有一组数据2a467它们的平均数是5则这组数据的中位数是__
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15分Thebestwaytodealwithsportsinjuriesistokeepthemfromhappeninginthefirstplace.Knowingtherulesofthegameyouareplayingandusingtheright1equipcangoalongwaytowardpreventinginjuries.Ifyouthinkyouhavebeeninjuredpull2yououtofthegameorstop3doyouractivityorworkout.Letacoachorparentknowwhathappenedincaseyouneedtoseeadoctor.Seriousheadandneckinjurieshappenmostoftentoathletes4playcontactsportslikefootball.Keeptheinjuredpersonstillwithhisorherhead5holdstraightwhilesomeonecallsforemergency6medicinehelp.Iftheperson7lieonthegrounddonottrytomovehimorher. Yourfirstquestionafterasportsinjurywill8probablebeWhencanIplayagain?Thisdependsontheinjuryandwhatyourdoctortellsyou.Evenifyoucan'treturntoyoursportrightawayadoctormighthavesuggestionsandadvice9whatyoucandotostayfit.Alwayscheckwithyourdoctor10tryinganyactivityfollowinganinjury.
已知ABCDE五种物质均为教案备课库中常见的物质它们相互转化的关系如图所示． 如果AB均为黑色固体C是造成温室效应的主要气体E是一种能使带火星的木条复燃的气体D是一种红色的固体单质．则C的化学式是A与B反应的化学方程式为 反应的基本类型是．
水是生产生活中不可缺少的物质．下列关于水的说法中正确的是
8分TheCoralSeaishometoanamazingvarietyofturtlessharkswhalesdolphinslargefishbirdscoralsplantsandmanyotherspecies.ManyofthesespeciesareendangeredelsewhereintheworldbutstillsurviveinthehealthyenvironmentoftheCoralSea. TheCoralSeaisalargeseriesofcoralreefslocatedoffthenortheastcoastofAustralia.ThisareaisthreetimeslargerthanAustralia'sfamousGreatBarrierReefwhichtheCoralSeaborders. TheCoralSeaisoneofthefewcoralreefenvironmentsthathaveremainedlargelyundamagedbyover﹣fishingoilandgasexplorationandpollution.Howeverstatisticsshowthatcoralreefsaroundtheworldaredisappearingfivetimesfasterthanrainforests.ItisverylikelythatinthenearfuturetheCoralSeawillfacethesamethreatstoitsexistence. TheAustraliangovernmentiscurrentlylookingatoptionsforprotectingtheCoralSeabuthasmadenodecisions.EnvironmentalistsarepushingforlawstodeclaretheCoralSeaareaamarineprotectedarea.Thisworldmeanalargeno﹣takezoneforfishermenano﹣explorationzoneforgasandoilcompaniesandano﹣dumpzoneforpollution.ThisworldmaketheCoralSeaamarineparklargerthananyintheworld. WecanwriteletterstoAustralianleadersAustralianenvironmentalprotectionagenciesandAustralianfriendstoletthemknowthatpeopleworldwidesupportthisprotectionoftheCoralSea.Tolosethislastgreatmarinewildnessworldwouldbealossforthewholeworld. FormoreinformationCLICKhereplease. 1Whatistheauthor'spurposeinwritingthispassage? A.ToteachpeoplehowtoprotecttheCoralSea. B.TocallforthepublicawarenesstoprotecttheCoralSea. C.ToshowtheamazingfeaturesoftheCoralSea. D.ToexplainthefunctionoftheCoralSea. 2Youcanmostprobablyreadthispassage. A.inaguidebook. B.onawebsite C.inasciencetextbook D.onaTVshow 3WhatisthemainimportantreasonforprotectingtheCoralSea? A.TheCoralSeahometomanyspecieswilldisappearsoon. B.TheCoralSeaisrichinoilandgas. C.TheCoralSeaisthreetimeslargerthanGreatBarrierReef. D.TheCoralSeawillbeamarineparklargerthananyintheworld. 4Whichofthefollowingisnotmentionedinthepassage? A.ThereasonforprotectingtheCoralSea. B.ThewaytoprotecttheCoralSea. C.ThelocationoftheCoralSea. D.Themoney﹣raisingforsavingtheCoralSea.
元素周期律是学习和研究化学的重要工具．如表是元素周期表的部分信息 认真分析信息结合所学知识回答 1分析上表规律可推知表中X＝核电荷数为8的元素名称是该元素在化学变化中易填“得到”或“失去”电子． 2表示的是写粒子符号 3写出由812号元素组成的化学式 4氟元素的化学性质与表中填元素符号元素的化学性质相似． 5在第三周期中元素类型的变化情况是从左到右由元素过渡到元素并以稀有气体结尾．
下列转化能一步完成的是 ①CH4→CO2②HNO3→H2SO4③CaO→CaOH2④BaOH2→NaOH⑤C→Cu．
下列物质或方式中的“碳”主要不是针对碳单质的是
某溶液中含有CuNO32和AgNO3现向其中逐渐加入一定质量的铁粉进行处理并绘制参加反应的铁的质量与溶液中溶质种类的关系图．下列说法不正确的是
小海小林小明三同学一起测定双氧水溶液中溶质的质量分数． 查阅资料2H2O22H2O+O2↑常温下氧气密度为1.42g/L． 设计原理将一定质量的双氧水样品与二氧化锰混合测定反应产生的氧气的质量计算出H2O2的质量继而得双氧水溶液中溶质的质量分数． 过程方法1小海首先设计如图1向装有样品溶液20g的锥形瓶75g中投入0.5g二氧化锰待双氧水反应完毕后测得锥形瓶和反应后混合物的总质量为95.1g则产生氧气的质量是双氧水溶液中溶质的质量分数为． 2小林对小海的设计提出质疑后设计如图2的方案只在上述方案中的锥形瓶上加一干燥管请你说明小林质疑的理由是． 3小明通过思考后觉得他们的方案误差都较大于是小明设计如图3的方案试剂用量不变．请你说明小明认为他们误差较大的原因．如果要满足小明的要求该实验需用mL的量筒．
空气的成分中体积分数约占21%的是
如图为甲乙两种盐的溶解度曲线下列说法正确的是
有一包固体粉末可能含有碳酸钙硫酸铜硝酸钾硫酸钠氯化钡中的一种或几种．为确定其组成进行如下实验 1取该固体粉末少量加足量水搅拌静置得到白色沉淀上层为无色溶液 2过滤在白色沉淀中加入足量稀硝酸白色沉淀不溶解． 根据以上实验可推断原固体粉末中一定有的物质是一定没有的物质是不能确定的物质是为确定这包固体粉末的组成小华取原固体粉末8.00g加足量水充分溶解后其粉末中的成分恰好完全反应过滤将沉淀洗涤干燥．称得其质量为4.66g．通过计算后确定这包固体粉末的组成是．
二氧化钛TiO2可作水分解的光催化剂其中氧元素为﹣2价则钛元素的化合价为
在化学实验技能考试做完“二氧化碳的制取和性质”实验后废液桶中有大量的盐酸与氯化钙的混合溶液不考虑其他杂质．为避免污染环境并回收利用废液化学兴趣小组做了如下实验 取废液桶上层清液共11.88kg向其中加入溶质质量分数为21.2%的碳酸钠溶液．所得溶液pH与加入的碳酸钠溶液的质量关系如图所示 1通过如图可知当碳酸钠溶液质量加到kg时废液恰好处理完盐酸与氯化钙的混合溶液完全转化成氯化钠溶液． 2此时所得溶液能否用于该校生物兴趣小组的小麦选种选种液要求氯化钠的溶质质量分数在10%一20%之间请通过计算回答．
在地壳中含量最多的元素是
向100gCuSO4与H2SO4的混合溶液中加入质量分数为20%的氢氧化钠溶液产生沉淀的质量与所加氢氧化钠溶液的质量关系如图所示回答下列问题 1由图象可知NaOH先与混合溶液中发生反应． 2生成沉淀CuOH2的质量是多少 3当加入NaOH溶液的质量为40g时所得溶液中Na2SO4的质量分数是多少结果精确到0.1%
某化学兴趣小组的同学对一瓶久置的熟石灰粉末的组成进行实验探究请你一起参与他们的探究活动． 提出问题这瓶熟石灰粉末是否已经变质生成了CaCO3 进行猜想猜想一熟石灰全部变成了CaCO3． 猜想二熟石灰部分变成了CaCO3． 猜想一熟石灰没有变质． 设计实验该小组同学对猜想一设计了下列探究方案请你帮助他们完成下表中相关实验内容． 反思与应用 ①要证明猜想二成立可参照上述实验方案进行探究在步骤②中产生的实验现象是． ②熟石灰变质是由于用化学方程式表示．在教案备课库我们所学过的物质中还有举一例等具有这样的性质因此像熟石灰这类物质在实验室应保存．
除去下列各组物质中的少量杂质所用试剂和方法均正确的是
除去下列各物质中的少量杂质所选用的试剂方法均正确的是
1云南水资源丰富但分布不均．有些村民用地下水作为生活用水人们常用检验地下水是硬水还是软水生活中可用的方法降低水的硬度 2高铁酸钾K2FeO4是一种新型高效的多功能水处理剂．高铁酸钾受热时发生的反应为4K2FeO42R+4K2O+3O2↑则R是填化学式 3请举一例生活中节约用水的具体措施．
图示“错误操作”与图下面“可能产生的后果”不一致的是
下列实验方法一定能达到实验目的是
6分Igrewupinafamilythatatedinnertogethereveryevening.Althoughmyparentsenjoyedwinetheyrarelydrankduringtheweekandwerealwaysinmoderation节制.AsformyselfIwasn'tinterestedinalcoholicdrinksandneitherweremyhighschoolfriends. SowhenIarrivedoncampusformyfirstyearofuniversitylifeIwasabitshocked.Manydifferenteventshadbeenorganizedforthefreshmenbuttheyallhadonethingincommon﹣alcoholandplentyofit.NotwantingtobeleftoutIjoinedafewoftheevents.ButIalwaysreturnedhomeearlyfeelingdisappointed.Yourpersonalityinterestsandexperiencesdidn'tmatteratallonlyhowmanyalcoholicdrinksyoucouldabsorbbeforepassingout喝醉.ItseemedshallowtomeIwantedtogettoknowmynewclassmatesnothowfasttheycoulddownapintofbeer. GraduallyhoweverIrealizedthatrealfriendsdon'tjudgeyoubyhowmuchyoucandrinkandtherewereotherwaysofmakingfriends.IjoinedaphotographysocietytookafirstaidcourseandeveryweekendIwentcyclingwithaclassmate.IfoundthatbyengagingintheseactivitiesandsharingthefunoflearningnewskillstogetherinagroupIformedmuchstrongerbondswithmynewfriendsthaneventhestrongestalcoholicdrinkscouldencourage. AnothervaluablelessonIlearnedisthatit'sperfectlyokaytosayNoifyoudon'twanttodrink.HoweverinmanyWesternsocietiesespeciallytheUKbingedrinking狂喝hasbecomethenorm.Manypeoplewhodrinkdon'tnecessarilywanttobuttheygiveintothepeerpressure同伴压力﹣they'reafraidtosayNo. 1Whatshockedtheauthorwhenheentereduniversity? A.Thestrangecampus. B.Thepopularityofalcohol. C.Thedrunkenclassmates. D.Thelimitedactivities. 2Whydidtheauthorreturnhomeearlyfromtheeventsatfirst? A.Hewasn'tgoodatdrinking. B.Hehadnofamiliarclassmates. C.Hehatedthewaypeoplegotalong. D.Hewasleftoutbytheorganizers. 3Howdidtheauthorfinallymakerealfriendsatuniversity? A.BysayingNotoalcoholicdrinks. B.Bystayingawayfromgroupactivities. C.Bygivingintothepeerpressure. D.Byjoiningpeoplewithcommoninterests.
几种常见物质的pH范围如表其中酸性最强的是
设计方案是实验探究的保证感悟方法是探究的根本目的．某合作学习小组开展了如下探究．实验一检验氢氧化钠溶液中是否含有氢氧化钙．【分析】从组成上看氢氧化钙和氢氧化钠都属于碱它们在水溶液中都能解离出相同的填符号所以具有相似的化学性质．但由于解离出的Na+和Ca2+不同所以性质也有不同．设计实验时可加入能解离出CO32﹣的试剂利用CO32﹣与Ca2+结合产生白色沉淀这一特殊现象予以检验．【设计方案并实验】写出上述方案中出现白色沉淀的一个化学方程式．【方法感悟】在检验物质时要分析物质的组成和．据此选择加入恰当的试剂最后根据不同现象得出结论．【实验探究】实验二有一种白色固体可能含有氯化钠氢氧化钠碳酸钠硫酸钠和硝酸钡中的一种或几种为探究其组成某合作学习小组设计方案并进行了如图实验1上述实验中过滤操作用到的玻璃仪器有烧杯玻璃棒和．2小晶同学通过上述实验推知白色固体样品中一定不含有．3为确定白色固体样品中可能存在的物质小燕对沉淀C进行实验．4小虎同学认为白色固体中还有物质不能确认其是否存在．其理由是用化学方程式表示．如要确认只需将上述实验方案中所加的一种试剂改为即可．【方法感悟】若其他物质的存在对所检验的物质有干扰时可先将干扰物质转化再选择加入恰当的试剂最后根据不同现象得出结论．
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下列物品所使用的材料中不属于有机合成材料的是
25分假定你是李华收到了美国朋友彼得寄来的最新英文小说.请你给他回邮件内容包括: 1.小说收到; 2.回赠礼物; 3.礼物意义; 4.邀请他来华. 注意: 1.词数80左右; 2.可适当增加细节以使行文连贯.
10分Everyonecanbenefitfrommakinganefforttopracticegratitude感激everyday.Thefollowingthreestepscanhelpyoustartfeelingmoregratefulandappreciativeofthegoodthingsinyourlife: NoticetheGoodThingsinYourLife 1Payattentiontothesmalleverydaydetailsofyourlife﹣naturepeoplecommunitysheltercreaturecomfortslikeawarmbedoragoodmeal.Andthenstartagratitudejournal日记.Makingacommitment承诺保证towritingdowngoodthingseachdaymakesitmorelikelythatwewillnoticegoodthingsastheyhappen. EnjoytheFeelingofGratitude Therearemomentswhenyounaturallyrightthenandtherefeelfilledwithgratitude.ThesearemomentswhenyousaytoyourselfOhwowthisisamazing!orHowgreatisthis!Pause.2Letitsinkin.Enjoyyourblessingsinthemomenttheyhappen. ExpressGratitude Expressinggratitudeismorethanbeingpolite.3Showyourappreciationtosomeonewhoreallydidsomethingnice.Say:Itwasreallykindofyouto…Youdidmeabigfavorwhen…orThankyouforbeingtherewhen….4Holdthedooropenforthepersonbehindyouevenifitmeanswaitingalittlelongerthanyounormallywould. Truegratitudedoesn'tleaveyoufeelinglikeyouoweotherpeoplesomething﹣afterallifyou'vedonesomeoneafavoryouprobablydon'twantthepersontofeellikeyouexpectsomethingbackinreturn.5 A.It'saboutshowingyourheartfeltappreciation. B.Justnoticeandabsorb吸收吸入thatfeelingoftruegratitude. C.Youcanalsoexpressgratitudebydoingakindness. D.It'sallaboutfeelinggoodandcreatingacycleofgood. E.Starttonoticeandidentifythethingsyouaregratefulfor. F.Helpsomeonewithoutlettingthepersonfindoutitwasyou. G.It'samazingwhatyounoticewhenyoufocusonfeelinggrateful.
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