问题 填空题

现有下图所示的实验装置,请回答问题:

(1)在加入药品之前应对实验装置进行   

(2)用高锰酸钾制氧气可选用的发生装置是    (填字母序号,下同);用过氧化氢制氧气可选用的发生装置是     。你认为两套装置不一样的主要原因是                  

(3)某同学用E装置收集氧气,理由是     ,为什么导管口刚有气泡冒出时,不宜立即收集           

(4)若选用B装置制备气体时应注意什么              

答案

(1)检查装置的气密性

(2)A ;B 反应物的状态和反应条件不同

(3)氧气不易溶于水 刚开始冒出的是装置内的空气

(4)长颈漏斗插到液面以下,防止气体从长颈漏斗逸出

(1)制取一种气体前,一定要先检查装置的气密性,以免漏气而收集不到气体。

(2)中所选的发生装置一定要与所选择的制取方法相对应:高锰酸钾制氧气时,反应物是固体、需要加热,用A装置;过氧化氢制氧气反应物是液体、不需要加热,用B装置。装置的不同主要由反应物的状态和反应条件决定。

单项选择题

Blues Starting my own section of blues recommendations fills me with a creeping sense of guilt and complicity. Why Because I’m a white guy writing about an almost completely black genre-black, at least in its origins and in the artists that brought the blues to its zenith in the 50’s and 60’s Unlike, say jazz or soul , white performers played little or no positive role in the development of the blues. What positive effect whites had been far outweighed by the commercial exploitation and social exclusion blues pioneers met at every crossroads. Further, there have been absolutely no significant white blues performers. A few are only imitators. Most can’t even properly be called blues musician: they played rock , folk , or pop music influenced by the blues , and much of it was unabashedly horrible , Mostly, though , writing about the blues makes me feel complicit in the unseemly, modern "blues revival" , a movement almost completely white and unoriginal , a popular uprising of middle-class , middle-aged (usually drunk) white guys pretending that they know something about oppression , depravity, rebellion , and the contradictory celebration of life arises from those conditions . These things are the essence of the blues, and, being a middle-class, middle-aged white guy I can vouch that we know nearly nothing about them. So why am I here Well, I can also youth that the blues, like all music, is a universal language, and I have come to understand it academically, if not experientially. Eventually, I came to love blues music if only for its influence on music more akin to my world-rhythm and blues, soul, rock-but in its own right too. In a general way , the blues speak to things we all have in common-love , betrayal , anger , death-and , from that perspective , I , too , got a right to sing the blues-just , well , not in public. On the other hand, as mentioned above, the blues world is now dominated by while folks. The records are made by while performers, many of them talented and certainly well- meaning but often sanitized and uninspired in ways anathema to the blues. White blues musicians frequently teeter on the precipice of caricature. Like Amos N’ Andy they trade in grossly rendered black mannerisms; that they do it out of love for the form rather than derision of the race seems a poor excuse. Sadly, though, most modern blues records-the good ones as well as the bad-are sold almost exclusively to white folks, too. The black audience for blues music has dwindled down to an older, mainly southern crowd of diehard. So, let’s be honest. I come to praise that original style. Indeed, in my research and writing, I hope to increase my own understanding and appreciation for it. And I hold no particular grudge against modern blues, though modern players will be few and far between among my recommendations Mainly, I cannot ignore the fact that modern blues fans made rich men out of John Lee Hooker, B, B, King, Buddy Guy, and other deserving old masters. But, also, there are modern artists who have made great blues records, Many of these artists are from my home state of Texas, so it seems unpatriotic, if not dishonest, not to acknowledge this fact.

According to the author, the essence of the blues is something about ______.

A.the whites

B.the blacks

C.imitation, development and celebration

D.oppression, depravity and rebellion

问答题 简答题