问题 选择题

某Na2CO3、NaAlO2的混合溶液中逐滴加入1mol·L-1的盐酸,测得溶液中的CO2-3、HCO-3、AlO3、Al3+离子的物质的量与加入盐酸溶液的体积变化关系如图所示,则下列说法正确的是         (   )

A.原混合溶液中的CO2-3与AlO2的物质的量之比为1:2

B.V­1:V2=l:5

C.M点时生成的CO2为0.05mol

D.a曲线表示的离子方程式为:AlO2+H++H2O=Al(OH)3

答案

答案:D

由碳的守恒可知b、c曲线分别表示CO2-3、HCO-3的物质的量变化,而d表示HCO-3的物质的量变化,a表示AlO—2的物质的量变化,e表示Al3+的物质的量变化。故D项正确;M点时CO2-3恰好完全转化HCO-3为,没有气体生成,C项错误;根据a、c发生反应的离子方程式AlO—2+H++H2O=Al(OH)3↓和CO32-+H+=HCO3-,可知原混合溶液中的CO2-3与AlO—2的物质的量之比为1:1,A项错误;则V1为75mL,V2等于150mL加上150mL(溶解氢氧化铝的盐酸)为300mL,B项错误。综合后故选D。

多项选择题
阅读理解

“Have a nice day!” may be a pleasant gesture or a meaningless expression. When my friend Maxie says “have a nice day” with a smile, I know she sincerely cares about what happens to me. I feel loved and secure since another person cares about me and wishes me well.

“Have a nice day. Next!” this version of the expression is spoken by a salesgirl at the supermarket who is rushing me and my groceries out of the door. The words come out in the same tone (腔调)with a fixed procedure. They are spoken at me, not to me. Obviously, the concern for my day and everyone else’s is the management’s attempt to increase business.

The expression is one of those behaviors that help people get along with each other. Sometimes it indicates the end of a meeting. As soon as you hear it, you know the meeting is at an end. Sometimes the expression saves us when we don’t know what to say. “oh, you just had a tooth out? I’m terribly sorry, but have a nice day.”

The expression can be pleasant. If a stranger says “Have a nice day!” to you, you may find it heart-warming because someone you don’t know has tried to be nice to you.

Although the use of the expression is an insincere, meaningless social custom at times, there is nothing wrong with the sentence except that it is a little uninteresting. The salesgirl, the waitress, the teacher, and all the countless others who speak it without thinking may not really care about my day. But in a strange and comfortable way, it’s nice to know they care enough to pretend they care when they really don’t care all that much. While the expression may not often be sincere, it is always spoken. The point is that people say it all the time when they like.

小题1:How does the author understand Maxie’s word?

A.Maxie shows her anxiety to the author.

B.Maxie really wishes the author a good day.

C.Maxie encourages the author to stay happy.

D.Maxie really worries about the author’s security.小题2:What does the underlined sentence in Paragraph 2 mean?

A.The salesgirl is rude.

B.The salesgirl is bored.

C.The salesgirl cares about me.

D.The salesgirl says the words as a routine.小题3:By saying “Have a nice day,” a stranger may______.

A.try to be polite to you

B.express respects to you

C.give his blessing to you

D.share his pleasure with you.小题4:According to the last paragraph, people say “Have a good day” __________

A.sincerely

B.as thanks

C.as a habit

D.encouragingly小题5:What is the best title of the passage?

A.Have a Nice Day---- a Social Custom

B.Have a Nice Day----- a pleasant Gesture

C.Have a Nice Day----- a heart-warming Greeting

D.Have a Nice Day----- a polite ending of a Conversation