问题 问答题

化石燃料燃烧产生大量CO2大气中CO2含量过高会导致温室效应等环境问题.

(])与煤相比,用天然气作燃料的优点有哪些?

(2)根据下表提供的数据,通过计算说明分别用煤(主要成分为碳)、CH4作燃料时,对温室效应产生的差异.

1g物质完全燃烧放出的热量
CH456kJ
C32kJ

答案

(1)与煤相比,天然气燃烧的热值高,产生的二氧化碳少,对环境的影响小.

 故答案为:热值高;产生的二氧化碳少,对环境的影响小.

(2)设1g甲烷燃烧生成二氧化碳的质量为m;1g煤燃烧生成二氧化碳的质量为n.

CH4+2O2

 点燃 
.
 
2H2O+CO2

16                44

1g                m  

16
44
=
1
m

m=2.75g

C+O2

 点燃 
.
 
CO2

12        44

1g        n

12
44
=
1
n

n=3.67g

通过计算可知,1g煤燃烧比1g天然气燃烧生成的二氧化碳要多,所以燃烧天然气可以减缓温室效应.

故答案为:燃烧天然气可以减缓温室效应.

单项选择题

Honesty is the best policy, as the English saying goes. Unfortunately, honesty often deserts us when no one is watching, British psychologists reported last week.

Researchers at UK’s Newcastle University set up an experiment in their psychology department’s coffee room. They set a kettle, with tea, coffee and milk on the counter and hung up a sign listing the prices for drinks. People helping themselves to a cup of drink were supposed to put a few cents in the box nearby. The scientists hung a poster above the money box, and it changed each week between images of gazing eyes and pictures of flowers. The researchers found that staff paid 2.76 times more for their drinks when the image of the eyes was hung. "Frankly we were shocked by the size of the effect," said Gilbert Roberts, one of the researchers.

Eyes are known to be a powerful perceptual (感官的) signal for humans. "Even though the eyes were not real, they still seemed to make people behave more honestly," said Melissa Bateson, a behavioral biologist and leader of the study.

Researchers believe the effect sheds light on our evolutionary past. It may arise from behavioral features that developed when early humans formed social groups to strengthen their chances of survival For social groups to work, individuals had to co-operate, rather than act selfishly. "There’s an argument that if nobody is watching us, it is in our interests to behave selfishly. But when we’re being watched we should behave better. So people see us as co-operative and behave the same way towards us," Bateson said.

The new finding indicates that people have a striking response to eyes. That might be because eyes and faces send a p biological signal we have evolved to respond to. The finding could be put to practical use, too. For example, images of eyes could increase ticket sales on public transport and improve supervision systems to prevent antisocial behavior.

Images of eyes could be put up in the following places EXCEPT ().

A. subway entrances

B. supermarkets

C. back streets

D. hotel bedrooms

选择题