在爆炸危险场所,如有良好的通风装置,能降低爆炸性混合物的浓度,场所危险等级可以降低。

题型:判断题

问题:

在爆炸危险场所,如有良好的通风装置,能降低爆炸性混合物的浓度,场所危险等级可以降低。

考点:维修电工高级维修电工职业技能鉴定国家题库高级维修电工试卷2
题型:判断题

全冠基牙的各轴面向方()

A.外展2°~5°

B.外展6°~7°

C.聚合2°~5°

D.聚合6°~7°

E.聚合8°

题型:判断题

如图所示,当电键S接通后,通过线圈L的电流方向是__________,(填“从a到b”或“从b到a”,下同),通过灯泡的电流方向是_____ _____;电键S断开的瞬间,通过线圈L的电流方向是___________,通过灯泡的电流方向是___________。

题型:判断题

(15分) 某同学设计了如下图所示装置(部分夹持装置已略去),该装置可以用来进行多项

实验研究。

请回答:

(1)用上述装置探究影响化学反应速率的因素。

①圆底烧瓶中发生反应的离子方程式是      

②用上述装置进行实验,以生成9.0 mL气体为计时终点,结果为t1>t2

序号V(H2SO4)/mLc(H2SO4)/mol·L-1t/s
401t1
404t2
 

比较实验Ⅰ和Ⅱ可以得出的实验结论是      

③若将锌片换成含杂质的粗锌片,且控制其他条件使其与上述实验完全一致,所测得的反应速率均大于上述实验对应的数据。粗锌片中所含杂质可能是(填序号)      

a.石墨        b.银      c.铜          d.沙粒(二氧化硅)

(2)用上述装置测定粗锌片的纯度。

①连接好装置,检查装置气密性,称量粗锌片mg置于圆底烧瓶中,滴加足量稀硫酸,充分反应直至不再产生气体为止,测得气体体积为VL,则粗锌片的纯度为      

②本实验在读数前对量气管的操作是      

③本套装置中若考虑滴入的稀硫酸的体积(假设其它操作都正确),则测得的气体的体积将      。(填“偏大”、“偏小”或“无影响”,)

(3)用上述装置验证生铁在潮湿空气中会发生吸氧腐蚀。

①圆底烧瓶中的试剂可选用(填序号)      

a.NH4Cl溶液       b.C2H5OH           c.Na2CO3溶液       d.稀硫酸

②能证明生铁在潮湿空气中会发生吸氧腐蚀的现象是      

题型:判断题

In June 1985, two British mountaineers Joe Simpson and Simon Yates made the first-ever climb of the 21,000-foot snow-covered Siula Grande mountain in Peru. It was an exceptionally (26) job, but nothing compared to what was to (27) . Early in the process, Simpson (28) and broke his right knee. Yates could have (29) him but managed to find a way of (30) him down the mountains on a rope in a series of difficult drops. Then Simpson fell into a crevasse and Yates eventually had no (31) but to cut the (32) , completely convinced that his friend was now (33)

In his book on the (34) , Joe Simpson wrote:

(35) I looked at the distant moraines, I know that I must at least try I would probably (36) there among those rocks. If I died, well, that wasn’t so (37) , but I wouldn’t have (38) waited for it to happen. The (39) of dying no longer affected me as it had in the crevasse at first. I now had a chance to (40) it and struggle against it.

The survival of Yates himself was (41) . That Simpson somehow found a way of (42) out of the crevasse after 12 hours and then crawled and (43) himself six miles back to camp, (44) three days and might without food or drink, would be considered as a heroic fiction. But in fact it was so (45) .

42().

A. running

B. walking

C. climbing

D. escaping

题型:判断题

传染病原体是否可经血传播必须具备以下哪些基本条件?()

A.病原体必须能够随血流进入宿主或患者体内

B.被感染的献血者必须没有任何相应的疾病迹象和症状

C.无论是游离于被感染的献血者的血浆中或是存在于血细胞中,该病原体必须能自然存活一段时间

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