问题 选择题

下列4个坐标图分别示意实验过程中某些量的变化,其中正确的是

ABCD
向盛有MnO2的烧杯中加入H2O2溶液在某一密闭装置内

点燃红磷

加热一定量高锰酸钾固体向一定量石灰石中滴加稀盐酸

 

 

 

答案

答案:B

题目分析:A向盛有MnO2的烧杯中加入H2O2溶液,生成O2的质量应与加入H2O2溶液成正比。所以此项不正确。B在反应开始时,由于燃烧产生产生大量的热而使装置的温度升高,从而造成装置内的压强会变大。后期由于气体参与反应装置气体减少较明显、反应停止温度逐渐降低等因素,从而造成装置内的压强会逐渐变小。此项正确。C随着高锰酸钾固体在加热的情况下反应,固体的质量逐渐减少。而固体中锰元素的质量不变,所以其质量分数会逐渐变大。此项错误。D因为石灰石是一定量的,所以反应生成的二氧化碳应有一个最大值。此项错误。

阅读理解

阅读理解。

     Most shoplifters (商店扒手) agree that the January sales offer wonderful opportunities for the hard-working thieves. With the shops so crowded and the staff so busy, it does not require any extraordinary talent to help you to take one or two little things and escape unnoticed. It is known, in the business, as "hoisting".

     But now the hoisting game is not what it used to be. Even at the height of the sales, shoplifters today never know if they are being watched by one of those evil little balls that hang from the ceilings of so many department stores above the most desirable goods.

     As if that was not trouble enough for them, they can now be filmed at work and obliged to attend a showing of their performance in court.

     Selfridges was the first big London store to install (安装) closed-circuit videotape equipment to watch its sales floors. In October, last year, the store won its first court case for shoplifting using an evidence - a videotape clearly showing a couple stealing dresses. It was an important test case which encouraged other stores to install similar equipment.

     When the balls, called sputniks, first make an appearance in shops, it was widely believed that their only function was to frighten shoplifters. Their somewhat ridiculous (古怪的) appearances, the curious holes and red lights going on and off, certainly make the theory believable.

It did not take long, however, for serious shoplifters to start showing suitable respect. Soon after the equipment was in operation at Selfridges, store detective Brian Chadwick was sitting in the control room watching a woman secretly putting bottles of perfume into her bag.

"As she turned to go," Chadwick recalled, "she suddenly looked up at the sputnik and stopped. She could not possibly have seen that the camera was trained on (对准) her because it is completely hidden, but she must have had a feeling that someone was looking at her."

     "For a moment she paused, but then she returned to counter and started putting everything back. When she had finished, she opened her bag towards the camera to show it was empty and hurried out of the store."

1. January is a good month for shoplifters because ______.

A. thieves have much previous experience then

B. they don't need to wait for staff to serve them

C. there are always so many people in the stores

D. January sales offer them wonderful chances

2. The sputniks hanging from the ceiling are intended ______.

A. to watch the most desirable goods  

B. to make films that can be used as evidence

C. to frighten shoplifters by their appearance  

D. to be used as evidence against shoplifters

3. The case last October was important because ______.

A. the evidence supplied was accepted by court

B. the equipment could frighten shoplifters

C. the other shops began to copy the method

D. the store got all the stolen dresses back  

4. The woman stealing perfume ______.

A. was frightened by the shape of the sputnik  

B. guessed the sputnik was aiming at her

C. saw the detective sitting in the control room  

D. found the camera was busy filming her    

5. The woman's action before leaving the store shows that she ______.

A. decided she didn't want anything stolen

B. was sorry for what she had done  

C. would never do any stealing in this store

D. was afraid she would be arrested

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