问题 选择题

将盛有12mLNO2和O2的混合气体的量筒倒立于水槽中,充分反应后,还剩余2mL无色气体,则原混合气体中O2的体积是(  )

①1.2mL         ②2.4mL         ③3.6mL         ④4mL

A.①②

B.①③

C.②④

D.①④

答案

答案:D

题目分析:2ml的无色气体,不是O2就是NO (NO2为棕红色 也不可能是O2和NO混合气,混合气反应产生NO2)。

(1)剩余O2,NO2和O2反应,O2过量2ml,剩下10ml为O2和NO2的混合气,反应4NO2+O2+2H2O=4HNO3,NO2/O2=4/1,

参加反应的O2为2ml,O2共4ml。

(2)剩余2ml NO,O2完全反应,设O2体积为Xml,则NO2体积为(12-X) ml,Xml的O2可以使4Xml的NO2全部生成硝酸不产生NO,剩下(12-5X) ml的NO2在没有O2的情况下 3NO2+H2O=2HNO3+NO,产生(12-5X)/3ml的NO,(12-5X)/3=2,

X=1.2ml。故选D。

点评:本题考查的是二氧化氮和一氧化氮的性质及其计算,学生要熟练书写出发生的化学方程式,再结合假设法,进行计算,解答本题。

阅读理解

We sometimes think global warming or climate change is a problem very far away from our lives, and that only the government needs to worry about it. But it's hardly possible to completely stay out of it ­ scientists are now 95 percent sure that humans have been the “dominant cause” of global warming trends since the 1950s.

One of the conclusions of a report released on Sept 27 by the United Nations says that human activities have caused global temperatures to rise by 0.89 0C between 1901 and 2012. That might not seem like a lot, but the truth is that a major part of that heat has been absorbed into the oceans, which is not surprising given that they cover two thirds of Earth's surface. Also, water has a much greater capacity (容量) to absorb heat than the air does, according to The Economist. 

While many greenhouse gases occur naturally and are needed to keep the Earth warm enough to support life, humans' use of fossil fuels is the main source of excess (多余的) greenhouse gases. According to CNN, by driving cars, using electricity produced by burning coal and oil or heating our homes with coal or natural gas, we release a large amount of greenhouse gases into the atmosphere.

Your body can barely feel a difference of 0.89 0C, but the Earth's ecosystems are so sensitive that even small changes can disturb them. It often starts with the smallest creatures at the bottom of the food chain, eventually affecting bigger animals, many of which could end up becoming extinct.

Global warming is also linked to an increase in extreme weather. A larger amount of carbon dioxide traps more energy inside the atmosphere. This changes the patterns of storms and rainfall in many regions and can lead to droughts and floods. Worse still, melting sea ice in warmer oceans is causing sea levels to rise at a speed of more than three millimeters per year, according to The Guardian, which also increases the risk of flooding.

“The report should serve as another wake­up call that our activities today have a profound impact on society, not only for us, but for many generations to come,” French Michel Jarraud, secretary­general of the World Meteorological Organization, said at a news conference.

小题1:The underlined word “dominant” in the first paragraph means “ ________”.

A.common        

B.indirect

C.secondary

D.leading小题2:Which of the following statements is TRUE according to the passage?

A.Greenhouse gases have been proven to harm merely the Earth .

B.There is little we can do to prevent global warming.

C.Global warming can increase the chances of droughts and floods.

D.The hugeness of oceans makes them better absorbers of heat than the air.小题3:The rise in global temperatures between 1901 and 2012 ________.

A.is more harmful to smaller creatures than bigger ones

B.is not serious because most of the extra heat has been absorbed by the oceans

C.has made the Earth's ecosystems more sensitive to changes

D.is likely to cause many species to become extinct小题4:What is Michel Jarraud's attitude toward the report released by the UN?

A.Negative.

B.Supportive.

C.Doubtful.

D.Uninterested.

判断题