下列是酸溶液与碱溶液发生反应的各种关系,请用“>”“c(X-)。 ①混合溶液中c

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问题:

下列是酸溶液与碱溶液发生反应的各种关系,请用“>”“<”或“=”填空: 

(1) 取0.2 mol/LHX溶液与0.2 mol/L NaOH溶液等体积混合,测得混合溶液中c(Na+)>c(X-)。

①混合溶液中c(HX)      c(X-);   

②混合溶液中c(HX) + c(X-)        0.1 mol/L(忽略溶液体积变化);    

③混合溶液中由水电离出的c(OH-)      0.1 mol/L 的HX溶液中由水电离出的c(H+)。

(2) 如果取0.2 mol/LHX溶液与0.1 mol/LNaOH溶液等体积混合,测得混合溶液的PH>7,则说明在相同浓度时HX的电离程度       NaX的水解程度。

(3) 分别取pH=2的硫酸和醋酸各50mL,加入足量的镁粉,反应开始时,反应速率前者_________后者;充分反应后,相同条件下产生氢气的体积前者_________后者。

(4) 等浓度等体积的盐酸和醋酸,分别与等浓度的NaOH溶液反应,恰好中和时,消耗NaOH的体积前者__________后者,所得溶液的pH前者________后者。

考点:燃烧热水的离子积常数水电离的影响因素水的电离平衡
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自负的人心理的共同特点 [ ]

A.以他人为中心

B.以自我为中心

C.以集体为中心 

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唇联合处的黏膜癌的癌前病变主要是

A.结节性白斑

B.白色念珠菌白斑

C.扁平苔藓

D.盘状红斑狼疮

E.A+B

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小明沿水平方向用力推地面上的桌子,但没有推动.下列说法中正确的是(  )

A.人推桌子的力小于桌子受到的摩擦力

B.人推桌子的力等于桌子受到的摩擦力

C.人推桌子的力和桌子的重力是平衡力

D.桌子对地面的压力和地面对桌子的支持力是平衡力

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Don’t you just love ice skating every winter?I am sure,that since winter is approaching,your skates are set to come out,just waiting to be used.Impress your friends with your new trick on how to ice­skate backwards with the help of these tips.Skating backwards on ice is a bit difficult but once you master the basic,there’s nothing like it.Follow the steps given below and you will be able to skate backwards in no time.

Stand Straight

The first thing that you need to do is,stand straight.If you feel that you are falling backwards,then just put your chin(下巴) up and slightly bend your knees.Don’t worry;this happens to all.

Confidence Is What You Need

The most important step while learning how to skate backwards,is having enough confidence in yourself and in what you are doing.How can you achieve this?By practice.Just practice rolling backwards down a gentle slop every single day or just by pushing off from a wall or something of that sort.But before you do that,make sure that the place where you are practicing is free from any kind of debris(碎片) because otherwise,you could land up in the hospital due to some accident.While going backwards,just get used to the feeling of moving backwards.One of the important ice skating tips and techniques is that if you feel that you are losing your balance,then scissor(做剪式运动) your skates.Keep practicing this till you are confident about it.

Maintain Speed

Confident now?Great!Now the next step is to maintain your speed.While rolling in a straight line with one skate,with the other try sculling(划桨),that is,keep pushing yourself backwards with an outwards stroke(滑动).Now bring the skate which you were using to scull,and then again,repeat the same process.Make sure that you put most of your weight on the skate which is moving straight and not the one with which you are sculling.Now,try the same thing using the other foot.Again keep doing this till you are confident enough.

Increase Your Speed Now

Once you are confident that you can scull with either foot,the next thing that you have to do is increase your speed.Try some of your own tricks now.Scull with either foot or with both at the same time.

Scull and Be Aware

While you keep one foot straight,keep sculling with the other.You can do that simultaneously with both feet.Concentrate on what you are doing but don’t get so involved,that you don’t see where you are going.If you are not watching your back,you might just bang against something or someone.

小题1:According to the text confidence comes from ______.

A.high speed

B.strict coaches

C.constant exercise

D.good techniques小题2:Which is the right order of ice­skating backwards?

a.Increasing your speed.

b.Being able to scull with one foot.

c.Being about to stand straight.

d.Trying some different tricks.

A.c→a→d→b

B.c→b→d→a

C.a→c→b→d

D.c→b→a→d小题3:In order to keep balance when skating backwards you should ________.

A.skate in a scissor gesture

B.use both your feet to scull

C.skate forward first and then backward

D.put most of your weight on the skate with which you are sculling小题4:The purpose of the text is ________.

A.to compare different ways of ice­skating backwards

B.to introduce the culture of ice­skating backwards

C.to explain advantages of ice­skating backwards

D.to offer some advice on ice­skating backwards

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PLC系统调试的程序测试方法主要有()。

A、白盒测试法

B、黑盒测试法

C、自顶向下测试法

D、自底向上测试法

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