问题 实验题

从事科学实验的重要环节是进行科学实验设计.科学实验的正确步骤应为:

①明确实验 目的;

②收集有关资料;

③设计合理方案;

④进行科学实验.在实验室中制取一定量的氧气,并进一步研究物质燃烧的条件.进行实验的装置如图. 查阅到着火点资料:

①实验开始前必须进行的操作______,在实验室中用过氧化氢(H2O2)在“A”装置中制取氧气.其反应的化学方程式为:___________

②实验室中收集氧气的方法可以是_______________. 实验装置如图:

实验时,室温为 18℃,整套装置中 C、E、F 的试管中白磷浸没在水中,C、D、F 装置 浸入 50的水中进行实验.

③产生氧气后,则 B 到 F 的装置中的白磷或红磷能发生燃烧的是 _ (选填 B 到 F的装置编号).通过 C、F 装置的对比得出燃烧的条件要具备: _________ ,通过 C、D 装置的对比得出燃烧的条件要具备:_______________

④为了证明金刚石也是碳元素的同素异形体,有同学设计了如图的实验装置,待金刚石燃烧完全后,检验生成的气体.现要引燃金刚石,你的最合理的方法是:__________________

答案

①检查装置气密性;2H2O22H2O+O2

②向上排空气法;排水法

③C;燃烧需要可燃物与氧气接触;可燃物必须达到着火点

④使用强光源集中加热引燃金刚石

单项选择题

As one works with color in a practical, or experimental way, one is impressed by two apparently unrelated facts. Color as seen is a mobile, changeable thing (1) to a large extent on the relationship of the color (2) other colors (3) simultaneously. It is not (4) in its relation to the direct stimulus which (5) it. On the other hand, the properties of surfaces that give (6) to color do not seem to change greatly under a wide variety of illumination color, usually (but not always) looking much the same in artificial light as in daylight. Both of these effects seem to be (7) in large part to the mechanism of color (8) .

When the eye is (9) to a colored area, there is an immediate readjustment of the (10) of the eye to color in and around the area (11) . This readjustment does not promptly affect the color seen but usually does affect the next area to which the (12) is shifted. The longer the time of viewing, the higher the (13) , and the larger the area, the greater the effect will be (14) its persistence in the (15) viewing situation. As indicated by the work of Wright and Schouten, it appears that, at (16) for a first approximation, full adaptation takes place over (17) time if the adapting source is moderately bright and the eye has been in (18) darkness just previously. Also, (19) of the persistence of the effect if the eye is shifted around from one object to another, all of which are at similar brightness or have similar colors, the adaptation will tend to become (20) over the whole eye.

17()

A.brief

B.complete

C.light

D.narrow

单项选择题