(5分)用实验确定HCOOH是弱电解质。两同学的方案是: 甲:①称取一定质量的H

题型:实验题

问题:

(5分)用实验确定HCOOH是弱电解质。两同学的方案是:

甲:①称取一定质量的HCOOH配制0.1 mol·L1的溶液100 mL;

②用pH试纸测出该溶液的pH,即可证明HCOOH是弱电解质。

乙:①用已知物质的量浓度的HCOOH溶液、盐酸,分别配制pH=1的两种酸溶液各100 mL;②分别取这两种溶液各10 mL,加水稀释为100 mL;③各取相同体积的两种稀释液装入两个试管,同时加入纯度相同的锌粒,观察现象,即可证明HCOOH是弱电解质。

(1)在两个方案的第①步中,都要用到的定量仪器是                    

(2)甲方案中,说明HCOOH是弱电解质的理由是测得溶液的pH       1(选填>、<、=)。

乙方案中,说明HCOOH是弱电解质的现象是              

a.装HCl溶液的试管中放出H2的速率快;

b.装HCOOH溶液的试管中放出H2的速率快;

c.两个试管中产生气体速率一样快:

(3)一定温度下有:a.盐酸;b.硫酸;c.醋酸三种酸。

①当其物质的量浓度相同时,c(H+)由大到小的顺序是___________________________。

②当c(H+)相同、体积相同时,同时加入镁,若产生相同体积的H2(相同状况),则开始时的反应速率____________________。(用a b c的大小关系表示)

考点:设计实验方案及探究实验
题型:实验题

阅读理解。

     My mind went blank when I saw the gun pointing against the car window as we pulled out of

the garage. This can't be happening to me. Then I felt the gun, cold, against my head, and I heard

my friend Jeremy saying, "What do you want? Take my wallet," but at the time I thought of nothing.

     I remember being a little annoyed when the gunman pulled me from the car by the hair. I remember

the walk to the house-Jeremy, me, the two men with two guns. I remember the fear and anger in the

gunmen's voices because Jeremy was being slow, and I remember wondering why he was being slow.

I did not realize that Jeremy had thrown the keys into the bush. But I remember that sound of the gun

hitting Jeremy's head and the feeling as the man who had hold of my hair released me. And I remember

the split second when I realized he was looking at Jeremy, and I remember wondering how far I

could run before he pulled the trigger. But I was already running, and upon reaching the car across t

he street, I didn't crouch(蹲伏) behind it but screamed instead.

     I remember thinking there was something ridiculous and illogical about screaming "Help, help!" at

eight o'clock on a Tuesday evening in December and changing my plea(恳求) to the more specific

"Help, let me in, please let me in!" But the houses were cold, closed, unfriendly, and I ran on until I

heard Jeremy's screams behind me announcing that our attackers had fled.

     The neighbors who had not opened their doors to us came out with baseball bats and helped

Jeremy find his glasses and keys. In a group they were very brave. We waited for the police to come

until someone said to someone else that the noodles were getting cold, and I said politely, "Please go

and eat. We're O.K."

     I was happy to see them go. They had been talking of stricter sentences for criminals, of bringing

back the death penalty(处罚) and how the President is going to clean up the country. I was thinking,

they could be saying all of this over my dead body, and I still feel that stiffer sentences wouldn't

change a thing. In a rush all the anger I should have felt for my attackers was directed against these

contented people standing in front of their warm, comfortable homes talking about all the guns they

were going to buy. What good would guns have been to Jeremy and me?

     People all over the neighborhood had called to report our screams, and the police turned out in

force twenty minutes later. They were ill-tempered about what was, to them, much trouble about

nothing. After all, Jeremy was hardly hurt, and we were hopeless when it came to describing the

gunmen. "Typical," said one policeman when we couldn't even agree on how tall the men were.

Both of us were able to describe the guns in horrifying detail, but the two policemen who stayed

to make the report didn't think that would be much help.

The policemen were matter-of-fact about the whole thing. The thin one said, "That was a stupid thing to do, throwing away the keys. When a man has a gun against your head you do what you're told." Jeremy looked properly embarrassed.

Then the fat policeman came up and the thin one went to look around the outside of the house. "That was the best thing you could have done, throwing away the keys," he said. "If you had gone into the house with them…" His voice became weaker. "They would have hurt her" --- he twisted his head toward me - "and killed you both." Jeremy looked happier. "Look," said the fat policeman kindly, "there's no right or wrong in the situation. There's just luck."

All that sleepless night I replayed the moment those black gloves came up to the car window. How long did the whole thing last? Three minutes, five, eight? No matter how many hours of my life I may spend reliving it, I know there is no way to prepare for the next time --- no intelligent response to a gun. The fat cop was right. There's only luck. The next time I might end up dead.

And I'm sure there will be a next time. It can happen anywhere, anytime, to anyone. Security is an illusion(幻觉); there is no safety in locks or in guns. Guns make some people feel safe and some people feel strong, but they're fooling themselves.

1. When the writer saw the gun pointing against the car window, ______.

A. she felt very annoyed              

B. she lost consciousness

C. she felt very much nervous          

D. she lost the power of thinking

2. What most possibly drove the two gunmen away?

A. Jeremy's fighting                

B. The author's screaming    

C. Their neighbour's brave action      

D. The police's arrival

3. The police were rather angry because ______.

A. the author was not hurt and gave a false alarm 

B. they thought it was a case of little importance

C. the author and Jeremy could not tell the police anything

D. the gunmen had already fled when they arrived on the scene

4. What the author wants to tell us is that______.

A. neighbors are not helpful in moments of difficulty

B. the police are not reliable when one is in trouble

C. security is impossible as long as people can have guns

D. preventing robbers entering your house is the best choice

题型:实验题

患者男性,47岁,因"发现颈部包块伴乏力、消瘦3个月余"入院。患者于3个月前无意中发现右颈包块,约2cm×2cm大小,伴四肢无力,身体消瘦,3个月来上述症状逐渐加重,体重下降8kg,为求进一步诊治转入院。查体:T37.6℃,一般情况差,ECOG2级,形体消瘦,体重50kg,双颈可及多个肿大淋巴结,最大者约3cmX3cm,表面红肿,压之部分有疼痛,心肺未见异常,肝脾不大,双上肢手指肿胀,双下肢无水肿。实验室资料:血常规、肝肾功能正常,LDH明显升高,达1202mmol/L,胸片、肝脾B超检查未见异常;骨髓涂片示三系增生且未见异常细胞。右颈淋巴结活检病理:外周T细胞性淋巴瘤(非特异型)。

化疗可选择的方案有()。

A.CHOP

B.EPOCH

C.ABVD

D.MOPP

E.BACOP

F.ABVD联合利妥昔单抗

题型:实验题

古代的物流管理主要包括哪三个方面?

题型:实验题

该图描绘了我国古代的播种工具,下列现象与其发明者无关的是()

A.耦犁的推广

B.翻车的发明

C.代田法的推行

D.条播机雏形的出现

题型:实验题

高频电的频率越高、功率越大,距离越近时对人体健康影响可能越大,下列安全防护措施不包括()

A.减小治疗室内高频电疗仪的密度可降低室内电磁波的强度

B.治疗操作时不使辐射器空载或对着周围环境中的人员

C.避免高频电对眼、睾丸部位的大强度辐射。妊娠期间不接受高频电治疗,不在高频电环境中工作

D.增加环境内金属物品可以减少金属对高频电磁波的反射

E.密切接触大强度微波者可戴微波防护眼罩或穿微波防护服

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