问题 选择题

现有一瓶无色液体X,将其分成等量的三份,分别向其中加入少量的碳酸钾溶液、氯化钡溶液、硫酸钠溶液,产生的现象如下表所示。则该无色液体X是

答案

答案:C

题目分析:加碳酸钾溶液产生无色的气体,所以X是一种酸,盐酸或硫酸,与碳酸钾反应的时候会放出二氧化碳气体,加氯化钡出现白色的沉淀,可以确定为硫酸,因为硫酸能和氯化钡反应生成硫酸钡和氯化氢,而盐酸与氯化钡是不反应的,加硫酸钠,硫酸和硫酸钠也是不发生反应的,所以通过以上分析可知无色溶液X为稀硫酸溶液,故选C

单项选择题
阅读理解

     Scientists studying the impact of climate change on the Arctic need to consider ways to reduce their

own carbon footprints(碳排放量), says Ryan Brook, a researcher who regularly flies north to study the

health of caribous (驯鹿). He calls on scientists to show leadership by examining and sharing ways to

reduce the impact of working in polar regions.

     "The importance of the research is not at question here. It is important to our understanding of and

adapting to climate change. But we need to think about better approaches." says Brook.

     "This is an issue for all scientists, though polar researchers often travel particularly long distances

using commercial air travel. We also rely extensively on small aircraft, icebreakers, and snowmobiles, all

of which produce large amounts of carbon. "

     Brook studies the health of caribous herds in Nunavut and Northwest Territories. He works with

northern wildlife managers. This work typically takes him north five or six times per year and when he

calculated his own carbon footprint, he was not happy with the result.

     "My research footprints are about the same as the annual footprints of an average Toronto resident.

Basically, I have two footprints-my own personal life, which is moderate, and my research footprint."

     Climate scientists can rightly argue that Arctic research is a specialized field and the community of

scientists who travel north is relatively small. Even if all scientists working in the north reduced their

carbon emissions, it would not make a big impact on the global scale. For Brook, it's the option that

matters.

     There are ways researchers can reduce the amount of carbon they use. Some helicopters use less

fuel than others. Solar and wind power are alternatives to gasfired generators. And while carbon offsets

(抵消) don't reduce the amount of carbon emitted, they are an easy first step.

     "There aren't necessarily any easy answers, but we need to start talking about it." says Brook. "This is

particularly important for the next generation of scientists being trained and I hope to see them become

leaders in this issue."

1. The underlined word"It" in Para. 2 refers to________.

A. the research of climate change on the Arctic

B. the study of the health of caribous

C. the impact of working in polar regions

D. the reduction of polar scientists' carbon emissions

2. What did Brook find when he calculated his own carbon footprints?

A. His carbon footprints are more than the annual footprints of a Toronto resident.

B. His personal life footprints are more than the annual footprints of a Toronto resident.

C. His research footprints are about the same as his personal life footprints.

D. His personal life footprints are more than his research footprints.

3. Brook's opinion is challenged by the statement that____.

A. arctic research is very important

B. the Arctic is a special environment

C. the footprints of Arctic scientists are small

D. Brook's situation is not a common phenomenon

4. We can infer from the last paragraph that________.

A. we should take actions immediately instead of just talking

B. it's easy to start talking about the problem of carbon emissions

C. it's necessary now to pay attention to the problem of research footprints

D. the next generation of scientists are more interested in research footprints