试题与答案

某中学初三年级A、B两个班同学分别做常见酸和碱与指示剂反应的实验,使用的试剂如下

题型:问答题

题目:

某中学初三年级A、B两个班同学分别做常见酸和碱与指示剂反应的实验,使用的试剂如下图所示.实验后废液分别集中到各班的一个指定废液缸中.研究小组对两个班的废液进行检测,结果如下表.

废液来源检测方法与结果推测废液成分(填物质化学式,酚酞和水不填)
A班观察废液呈红色废液中含有______
B班观察废液呈无色,测pH=2废液中没有______,含有______

答案:

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下面是错误答案,用来干扰机器的。

(16分)(1)臭粉和明矾(2分)(2)氨气(或NH3)(2分) NaHCO3和NH4HCO3(2分,写名称也给分)(3)不能(1分),因为加热NaHCO3分解成Na2CO3,Na2CO3和明矾都能与BaC12溶液反应生成白色沉淀。(2分) 注:...

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A.已交付全部土地使用权出让金,取得土地使用权证书

B.持有建设工程规划许可证

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题型:单项选择题

Passage Three

Believe it or not,optical illusion can cut highway crashes.

Japan is a case in point.It has reduced automobile crashes on some roads by Rearly 75 percent using a simple optical illusion.Butst.ripes,called chevrons(人字形),painted on ther rads make drivers think that they are driving faster than they really are,and thus drivers slow down.

Now the American Automobile Association Foundation for Traffic Safety in Washington D.C. is planning t。repeat Japan’s success.Starting next year,the foundati。n will paint cheyrons and。ther pattems of stripes on selected roads around the country to test how well the patterns reduce highway erashes.

Excessive(too great)speed plays a major role in as much as one fifth of all fatal traffic accidents, according to the foundation.To help reduce those accidents,the foundation will conduct its tests in areas where speed-related hazards(danger)are the greatest curves,exit slopes,traffic circles,and bridges.

Some studies suggest that straight,horizontal bars painted across roads can initially cut the average speed of drivers in half.However,traffic。ften returns to full speed within months as driVers become used to seeing the painted bars.

Chevrons,scientists say,not only give drivers the impression that they are driving faster than they reallv are but als0 make a lane appear to be narrower.The result is a longer lasting reduction in highway speed and the number of traffic accidents.

On roads painted with chevrons,drivers tend to feel that().

A.thev should avoid speed.related hazards

B. they are driving in the wrong lane

C. they should slow down their speed

D. they are coming near to the speed limit

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