问题 选择题

莫尔盐[(NH42Fe(SO42•6H2O]常作氧化还原滴定法的基准物质,在0.1mol/L 的该盐的溶液中,下列有关比较不正确的是(  )

A.c(SO42-)>c(NH4+)>c(Fe2+)>c(H+)>c(OH-

B.c(NH3•H2O)+c(NH4+)=0.2mol/L

C.2c(SO42-)+c(OH-)=c(NH4+)+2c(Fe2+)+c(H+

D.c(H+)=c(OH-)+c(NH3•H2O)

答案

A.在(NH42Fe(SO42•6H2O溶液中,存在NH4+、Fe2+、SO42-、OH-、H+,由于 NH4+、Fe2+ 都水解,导致二者的浓度都减小,即 c(NH4+)<0.2mol/L,c(Fe2+)<0.1mol/L,

NH4+、Fe2+ 水解使溶液呈酸性,即 c(H+)>c(OH-).因为盐类水解程度较小,因此 c(Fe2+)>c(H+),则c(SO42-)>c(NH4+)>c(Fe2+)>c(H+)>c(OH-),故A正确;

B.根据NH4++H2O⇌H++NH3•H2O知,氮原子有两种存在形式,即NH4+、NH3•H2O,根据氮原子守恒,c(NH3•H2O)+c(NH4+)=0.2mol/L,故B正确;

C.在 (NH42Fe(SO42•6H2O溶液中,存在NH4+、Fe2+、SO42-、OH-、H+,由电荷守恒得:2c(SO42-)+c(OH-)=c(NH4+)+2c(Fe2+)+c(H+),故C正确;

D.根据质子守恒,水电离产生的H+与OH-数目相等,结合NH4++H2O⇌H++NH3•H2O和Fe2++2H2O⇌Fe(OH)2+2H+,可得c(H+)=c(OH-)+c(NH3•H2O)+2Fe(OH)2,故D错误;

故选D.

完形填空
Because my family were not going to be helpful, I decided I would look for one all by myself and not tell them about it till I’d got one.
I had seen an agency advertised in a local newspaper. I rushed out of the 36 in search of it. I was wildly excited, and as  37 as if I were going on the stage. Finding the 38  quite easily, I ran breathlessly through a door which said “Enter without knocking, if you please.”
The simple atmosphere of the office 39  me. The woman looked carefully at me 40 through her glasses, and then 41  me in a low voice. I answered softly. All of a sudden I started to feel rather 42 ,She wondered why I was looking for this sort of 43  . I felt even more helpless, when she told me that it would be 44  to get a job without 45 .I wondered whether I ought to leave,  46  the telephone on her desk rang, I heard her say:“ 47  , I’ve got someone in the 48  at this very moment, who might 49  .” She wrote down a 50  , and held it out to me, saying: “Ring up this lady. She wants  a 51  immediately. In fact, you would have to start tomorrow by cooking a dinner for ten people.”
“Oh yes,” said I — 52  having cooked for more than four in my life. I 53  her again and again, and rushed out to the 54  telephone box. I collected my thoughts, took a deep breath, and rang the number. I said confidently that I was just what she was looking for.
I spent the next few hours 55  cook books.
小题1:A. bed           B house             C. agency       D. office
小题2:
A.proudB.pleaseC.nervousD.worried
小题3:
A.familyB.doorC.placeD.stage
小题4:
A.calmedB.excitedC.frightenedD.disturbed
小题5:
A.as usualB.for a whileC.in a minuteD.once again
小题6:
A.advisedB.examinedC.informedD.questioned
小题7:
A.encouragedB.dissatisfiedC.hopelessD.pleased
小题8:
A.placeB.jobC.adviceD.help
小题9:
A.difficultB.helplessC.possibleD.unusual
小题10:
A.abilityB.experienceC.knowledgeD.study
小题11:
A.afterB.sinceC.untilD.when
小题12:
A.Above allB. As a matter of fact
C.As a resultD.In spite of that
小题13:
A.familyB.houseC.officeD.restaurant
小题14:
A.hireB.acceptC.suitD.offer
小题15:
A.letterB.nameC.noteD.number
小题16:
A.cookB.helpC.teacherD.secretary
小题17:
A.almostB.neverC.nearlyD.really
小题18:
A.answeredB.promisedC.thankedD.told
小题19:
A.outsideB.localC.closestD.nearest
小题20:
A.borrowingB.buyingC.readingD.writing
单项选择题 A1/A2型题