搜题请搜索小程序“爱下问搜题”
问题 选择题

下列与化学反应能量变化相关的叙述中正确的是

A．已知CH4(g)＋2O2(g)=CO2(g)＋2H2O(g) ΔH＝-802 kJ/mol，甲烷的燃烧热为802 kJ/mol

B．等量H2在O2中完全燃烧，生成H2O(g)比生成H2O(l)放出的热量多

C．同温同压下，H2(g)＋Cl2(g)=2HCl(g)在光照和点燃条件下的ΔH不同

D．由石墨比金刚石稳定可知：C(金刚石, s)=C(石墨, s) ΔH<0

答案

答案：D

题目分析：A、根据燃烧热的概念：“在25℃，101 kPa时，1 mol可燃物完全燃烧生成稳定的氧化物时所放出的热量，叫做该物质的燃烧热，单位为kJ/mol。”知水的状态应为液态，错误；B、由于H2O(g)转化为H2O(l)放出热量，所以等量H2在O2中完全燃烧，生成H2O(g)比生成H2O(l)放出的热量少，错误；C、ΔH的取决反应物和生成物的能量高低，与反应条件无关，错误；D、由石墨比金刚石稳定，石墨具有的能量比金刚石低，可知：C(金刚石, s)=C(石墨, s) ΔH<0，正确。

选择题

She loves the song     , because her mother was once the singer of it.

A．in practice

B．in theory

C．in particular

D．in reality
查看答案
单项选择题

We can make mistakes at any age. Some mistakes we make are about money. But most mistakes are about people. One might say, "Did Jerry care when I broke up with Helen " "When I got that great job, did Jim really feel good about it, as a friend " Or "Did he envy my luck " "And Paul — why didn’t I pick up that he was friendly just because I had a car " When we look back, doubts like these can make us feel bad. But when we look back, it’s too late.
Why are we wrong about our friends or our enemies Sometimes what people say hides their real meaning. And if we don’t really listen, we miss the feeling behind the words. Suppose someone says to you, "You’re a lucky dog." Is he really on your side If he says, "You’re a lucky guy" or "You’re a lucky gal," that’s being friendly. But if he says, "You are a lucky dog." There’s a bit of envy in those words. Maybe he doesn’t see it himself. But bringing in the dog he put you down a little. What he may be saying is that he doesn’t think you deserve your luck.
"Just think of all the things you have to be thanking for" is another noise that says one thing and means another. It could mean that the speaker is trying to get you to see your problem as part of your life as a whole. But is he Wrapped up in this phrase is the thought that your problem isn’t important. It’s telling you to think of all the starving people in the world when you have not got a date for Saturday night.
How can you tell the real meaning behind someone’s words One way is to take a good look at the person talking. Do his words fit the way he looks Does what he says square with his tone of voice, his posture, the look in his eyes Stop and think. The minute you spend thinking about the real meaning of what people say to you may save another mistake.
Therefore, when you hear someone saying, please try to know what he really means. Don’t just listen to what he says with your ears but feel the words he uses with your head. In this way, you may make less mistakes.

In the first paragraph, the writer recalls some things that happened between him and his friends. He ______.

A．feels happy, thinking of how nice his friends were to him

B．feels he may not have read his friends true feelings correctly

C．thinks it was a mistake to have broken up with his girl friend, Helen

D．is sorry that his friends let him down
查看答案