题干

一定条件下,在体积为3 L的密闭容器中,一氧化碳与氢气反应生成甲醇(催化剂为Cu2O/ZnO): CO(g)+2H2(g)CH3OH(g),甲醇生成量与时间的关系如图所示。下列有关说法正确的是.

A:在300 ℃条件下,t1时刻该反应达到化学平衡

B:在500 ℃条件下,从反应开始到平衡,氢气的平均反应速率v(H2)为nB/(3t1) mol/L

C:在其他条件不变的情况下,将处于E点的体系体积压缩到原来的1/2,则氢气的浓度减小

D:由图像说明该反应的正反应为放热反应

上一题 下一题 0.0难度 选择题 更新时间:2018-02-27 06:05:34

答案(点此获取答案解析)

D

同类题1

阅读理解

    Teachers in some secondary schools in Britain are worried that their job may become impossible shortly unless something can be done to restore discipline in the classrooms. In the problem schools, mostly in large cities, a small minority of teenage pupils disturb lesson to such an extent that the teacher can no longer teach their classes effectively.

    Some people consider that the permissive (随意) nature of modern society is responsible for such kind of behavior. Small children who are continuously encouraged to express themselves without reservation are naturally unwilling to accept school discipline when they grow older. Furthermore, modern teaching techniques) which appear to stress personal enjoyment at the expense of serious study work, might be teaching the child to put his own interests before his duties to the community in which he lives.

    Perhaps the problem can be solved by improving facilities for the moral guidance of these difficult children or by better cooperation between the schools and the parents—for the parents may be mainly responsible for the bad behavior of their youngsters. Violence at home, violence and crime on TV make some children turn violence themselves.

    But some of the teachers believe that there ought to be a return to more “old fashioned” methods. At present, in some school teachers are even not allowed to punish a child who does something bad and wrong. Physical punishment is not permitted now. People are too soft on children these days. It seems that children can do whatever they like at school while the teachers can't do anything to punish them. I don't know why the schools authority abandoned some of the effective punishments that worked well. Things like that didn't happen when we were at school because the teachers kept those problem students under control by using a stick.