问题 多选题

下列关于过氧化氢分解中二氧化锰的说法错误的是(  )

A.某次过氧化氢分解时加入0.5克二氧化锰,反应后,过滤、烘干,得到二氧化锰的质量为0.5克

B.二氧化锰能加快过氧化氢的分解速率

C.二氧化锰是过氧化氢的分解产物之一

D.二氧化锰能使生成的氧气增多

答案

A、在过氧化氢分解反应中二氧化锰是催化剂,催化剂在反应前后的质量和化学性质不会发生改变,所以过氧化氢分解时加入0.5克二氧化锰,反应后,过滤、烘干,得到二氧化锰的质量为0.5克,是正确的,故正确;

B、二氧化锰是反应的催化剂,在此反应中会加快反应的速率,故正确;

C、过氧化氢分解的产物是水和氧气,二氧化锰是反应的催化剂,故错误;

D、二氧化锰在过氧化氢分解反应中是催化剂,催化剂可以改变反应的速率,但不能使产物的量增加,故错误.

故选CD.

单项选择题

People are indulging in an illusion whenever they find themselves explaining at a cocktail (鸡尾酒) party, say, that they are "in computers," or "in telecommunications," or "in electronic funds transfer". The implication is that they are part of the high-tech world. Just between US, they usually aren’t. The researchers who made fundamental breakthroughs in those areas are in a high-tech business. The rest of us are (71) of their work. We use computers and other new technology components to develop our products or to organize our affairs. Because we go about this work in teams and projects and other tightly knit working groups(紧密联系在一起的工作小组), we are mostly in the human communication business. Our successes stem from good human interactions by all participants in the effort, and our failures stem from poor human interactions.

The main reason we tend to focus on the (72) rather than the human side of the work is not because it’s more (73) , but because it’s easier to do. Getting the new disk drive installed is positively trivial compared to figuring out why Horace is in a blue funk (恐惧) or why Susan is dissatisfied with the company after only a few months. Human interactions are complicated and never very crisp (干脆的, 干净利落的) and clean in their effects, but they matter more than any other aspect of the work.

If you find yourself concentrating on the (74) rather than the (75) , you’re like the vaudeville character (杂耍人物) who loses his keys on a dark street and looks for them on the adjacent street because, as he explains, "The light is better there!".

 

73()

A.trivial

B.crucial

C.minor

D.insignificant

多项选择题