题干

下面是几种实验室制取气体的发生装置和收集装置。请回答下列问题:

请写出标有序号的仪器的名称:a____;b____
②采用装置A加热氯酸钾和二氧化锰的混合物制取氧气,反应的化学方程式为____,若要收集氧气选用____装置(选装置编号,下同),若用G装置装满水,采用排水法收集氧气,氧气应从____(选“c”或“d”)进。
③制取二氧化碳最好选用的发生装置是____,该装置与另一个可选用的装置相比,其主要优点是____
④用50g过氧化氢溶液与2g二氧化锰混合,充分反应后装置内剩余物质的质量为45.6g.求:
Ⅰ.生成氧气的质量____g;
Ⅱ.参加反应的过氧化氢的物质的量____。(根据化学方程式列式计算)
上一题 下一题 0.0难度 选择题 更新时间:2016-07-21 10:20:18

答案(点此获取答案解析)

铁架台,长颈漏斗,2KClO3 2KCl+3O2↑,D,d,C,随开随用,随关随停,6.4g,0.4mol

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    ____Friendships between Americans can be close and real, yet disappear soon if situations change. Neither side feels hurt by this. Both may exchange Christmas greetings for a year or two, perhaps a few letters for a while — then no more.____. This can be quite difficult for us Chinese to understand, because friendships between us develop more slowly but then may become lifelong feelings, extending (延伸) sometimes deeply into both families.

    Americans are ready to receive us foreigners at their homes, share their holidays, and their home life. They will enjoy welcoming us and be pleased if we accept their hospitality (好客) easily.

    There is another difficult point for us Chinese to understand.____ This is usually the opposite of the practice in our country where we may be generous (慷慨)with our time. Sometimes, we, as hosts, will appear at airports even in the middle of the night to meet a friend.____. The Americans, however, express their welcome usually at homes, but truly cannot manage the time to do a great deal with a visitor outside their daily routine. They will probably expect us to get ourselves from the airport to our own hotel by bus. And they expect that we will phone them from there.____. We will find ourselves treated hospitably(好客).

    For the Americans, it is often considered more friendly to invite a friend to their homes than to go to restaurants, except for business matters. So accept their hospitality at home!

A.Americans don't show their politeness if it requires a great deal of time.

B.Friendships between Americans usually extend deeply into their families.

C.Americans always show their warmth even if they are very busy.

D.Once we arrive at their homes, the welcome will be full, warm and real.

E.We may take days off to act as guides to our foreign friends.

F.If the same two people meet again by chance, even years later, they pick up the friendship.

G.America is a mobile society.