已知A为烃,B为烃的含氧衍生物.由等物质的量的A和B组成的混合物0.05mol在

题型:问答题

问题:

已知A为烃,B为烃的含氧衍生物.由等物质的量的 A 和 B 组成的混合物 0.05mol 在0.125mol 的氧气中恰好完全燃烧,生成 0.1mol 的 CO2 和 0.1mol H2O,试通过计算回答下列问题:

(1)从分子式的角度看,等物质的量A 和 B 组成的混合物平均组成可用化学式表示为______,

(2)另取一定量的A和B完全燃烧,将其以任意物质的量比混合,且物质的量之和一定,则:

①若耗氧量一定,则A和B的结构简式分别为:A______ B______

②若生成的CO2 和 H2O 的物质的量一定,则A和B的结构简式为:A______   B______.

考点:结构简式有机化学的有关计算
题型:问答题

下列各组离子在指定溶液中能大量共存的是(  )

①常温下,c(H+)/c(OH-)=1×10-12的溶液:K+、AlO2-、CO32-、Na+

②加入苯酚显紫色的溶液:K+、NH4+、Cl-、I-

③中性溶液:Fe3+、Al3+、NO3-、SO42-

④使pH试纸变蓝的溶液中:NH4+、Na+、SO42-、Cl-

⑤无色溶液中:K+、Al3+、NO3-、HCO3-

A.②③

B.①③

C.①

D.①④⑤

题型:问答题
甲、乙、丙三人射击命中目标的概率分别是
1
2
1
3
1
4
,现在三人射击一个目标各一次,目标被击中的概率是______.
题型:问答题

采用静止无功补偿装置()提高暂态稳定性。

A.可以

B.不可以

C.不确定是否可以

D.其他三个选项都不是

题型:问答题

For most people, shopping is still a matter of wandering down the street or loading a cart in a shopping mall. Soon, that will change. Electronic commerce (trade) is growing fast and will soon bring people more choices. There will, however, be a cost: protecting the consumer from being cheated will be harder. Many governments therefore want to apply street regulations to the electronic world. But politicians would be wiser to see cyberspace as a basis for a new era of corporate self-regulation.

Consumers in rich countries have grown used to the idea that the government takes responsibility for everything from the stability of the banks to the safety of the drugs or their rights to refund when goods are faulty. But governments cannot enforce national laws on businesses whose only presence is on the screen. Even in a country where a clear right to compensation exists, the on-line customer in Tokyo, say, can hardly go to New York to get a refund (退款) for a clothes purchase.

One answer is for government to cooperate more: to recognize each other’s rules. But that requires years of work and volumes of detailed rules. And plenty of countries have rules too fanciful for sober countries to accept. There is, however, another choice. Let the electronic businesses do the regulation themselves. They do, after all, have a self-interest in doing so.

In electronic commerce, a reputation for honest dealing will be a valuable competitive asset. Governments, too, may compete to be trusted. For instance, customers ordering medicines on- line may prefer to buy from the United States because they trust the rigorous screening of the Food and Drug Administration; or they may decide that the FDA’s rules are too strict, and buy from Switzerland instead.

Customers will still need to use their judgment, but precisely because the technology is new, electronic shoppers are likely for a while to be a lot more cautious than customers of the normal sort. And the new technology will also make it easier for them to complain when a company lets them down. In this way, at least, the advent(出现) of cyberspace may argue for fewer consumer protection laws, not more.

小题1:In case an electronic shopper bought faulty goods from a foreign country, what could he do?

A.Refuse to pay for the purchase.

B.Go to the seller and ask for a refund.

C.Appeal to consumer protection law.

D.Complain about it on the Internet.小题2:In the author’s view, businesses would place a high emphasis on honest dealing because in the electronic world _______.

A.international cooperation would be much more frequent

B.consumers could easily seek government protection

C.a good reputation is a great advantage in competition

D.it would be easy for consumers to complain小题3:We can infer from the passage that in licensing new drugs the FDA in the United States is______.

A.very quick

B.very cautious

C.very slow

D.rather careless小题4:According to the author, what will be the best policy for electronic commerce?

A.Self-regulation by the business.

B.Strict Consumer protection laws.

C.Close international cooperation.

D.Government protection.

题型:问答题

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