问题 问答题

为测定空气中氧气的含量,小华同学打算设计如下图所示的实验方案:

在一个隔热效果良好的容器上方安装一个可自由上下移动

的活塞(活塞质量忽略不计,起始位置在5刻度处).加热容器,

使容器温度达到80℃(已知白磷燃烧所需的最低温度为40℃).

请回答:

(1)实验过程中,可以观察到:白磷______,产生大量______,活塞先向______移动,再向______移动,最后停在刻度______处.

(2)由此实验得出的结论______.

(3)有位同学用木炭取代白磷来进行实验,结果实验失败,请你分析实验失败的原因是______.

答案

因所选药品是红磷,白磷在空气中燃烧和红磷燃烧现象相同,白磷燃烧产生白烟,放出大量的热,开始气体受热膨胀冷却后因消耗氧气(氧气约占空气总体积的五分之一),装置内压强减小,

故(1)答案:白磷燃烧,产生大量的白烟,活塞先向上移动,再向下移动,最后停在刻度4处.

由开始刻度指在5到实验后指在4处,可得到结论氧气约占空气总体积的五分之一,

故(2)答案:氧气约占空气总体积的五分之一.

木炭燃烧产生二氧化碳气体,反应前后气体压强基本不变,最后看不到活塞移动,

故(3)答案:木炭燃烧生成二氧化碳气体,容器内气体压强基本不变.

阅读理解

阅读理解

     Every day we experience one of the wonders of the world around us without even realizing it.It is not

the amazing complexity of television, nor the impressive technology of transport.The universal wonder we

share and experience is our ability to make noises with our mouths, and so transmit ideas and thoughts to

each other's minds.This ability comes so naturally that we tend to forget what a miracle(奇迹)it is.

   Obviously, the ability to talk is something that marks humans off from animals.Of course, some animals

have powers just as amazing.Birds can fly thousands of miles by observing positions of the stars in the

sky in relation to the time of day and year.In Nature's talent show, humans are a species of animal that

have developed their own special act.If we reduce it to basic terms, it's an ability for communicating

information to others,by varying sounds we make as we breathe out.

  Not that we don't have other powers of communication.Our facial expressions convey our emotions,

such as anger, or joy,or disappointment.The way we hold our heads can indicate to others whether we

are happy or sad.This is socalled "body language". Bristling (直立的) fur is an unmistakable warning of

attack among many animals.Similarly, the bowed head or dropping tail shows a readiness to take second

place in any animal gathering.

  Such a means of communication is a basic mechanism that animals, including human beings, instinctively

acquire and display.Is the ability to speak just another sort of instinct? If so, how did human beings

acquire this amazing skill? Biologists can readily indicate that particular area of our brain  where  speech 

 mechanisms  function, but  this doesn't tell us how that part of our bodies originated in our biological

history.

1. According to the passage, the wonder we take for granted is________.

A. our ability to use language

B. the miracle of technology

C. the amazing power of nature

D. our ability to make noises with mouth

2. What feature of "body language" mentioned in the passage is common to both humans and animals?

A. Lifting heads when sad.

B. Keeping long faces when angry.

C. Bristling hair when ready to attack.

D. Bowing heads when willing to obey.

3. What can be inferred from Paragraph 3?

A. Body language is unique to humans.

B. Animals express emotions just as humans do.

C. Humans have other powers of communication.

D. Humans are no different from animals to some degree.

4. This passage is mainly about________.

A. the development of body language

B. the special role humans play in nature

C. the power to convey information to others

D. the difference between humans and animals in language use

单项选择题 A1/A2型题