问题 选择题

由Na、S、O、H四种元素中的两种或三种元素组成的四种化合物,其中甲能跟氯化钡溶液反应生成两种盐;乙能跟盐酸反应生成盐和水;丙能跟苛性钠溶液反应生成盐和水;丁呈中性,跟氧化钠或二氧化硫均能发生化合反应.则下列推论中正确的是(  )

A.甲可能是Na2SO4

B.乙一定是NaOH

C.丙一定是H2SO4

D.丁可能是H2O

答案

A、甲能跟氯化钡反应生成一种硫酸盐和另一种盐,那么甲一定是盐,依据复分解反应的规律可知甲可能是硫酸钠,也可能是硫酸氢钠,硫酸氢钠与氯化钡的反应方程式为NaHSO4+BaCl2=BaSO4↓+NaCl+HCl,故选项正确;

B、乙能跟盐酸反应生成盐和水,则丙可以是氢氧化钠或氧化钠,故选项错误;

C、丙能跟氢氧化钠反应生成盐和水,则丙可以是硫酸、二氧化硫或三氧化硫三种物质,故选项错误;

D、丁呈中性,且可分别跟氧化钠或二氧化硫发生反应,会生成相应的碱或酸,那么丁一定是水.故选项错误;

故选A.

多项选择题
填空题

[A] A machine has been developed that pulps paper and then processes it into packaging, e.g. egg-boxes and cartons. This could be easily adapted for local authorities use. It would mean that people would have to separate their refuse into paper and non-paper, with a different dustbin for each. Paper is, in fact, probably the material that can be most easily recycled; and now, with massive increases in paper prices, the time has come at which collection by local authorities could be profitable.

[B] Recycling of this kind is already happening with milk bottles, which are returned to the dairies, washed out, and refilled. But both glass and paper are being threatened by the growing use of plastic. More and more dairies are experimenting with plastic bottles, and it has been estimated that if all the milk bottles necessary were made of plastic, then British dairies would be producing the equivalent of enough plastic tubing to encircle the earth every five or six days!

[C] The package itself is of no interest to the shopper, who usually throws it away immediately. Useless wrapping accounts for much of the refuse put out by the average London household each week. So why is it done Some of it, like the cellophane on meat, is necessary, but most of the rest is simply competitive selling. This is absurd. Packaging is using up scarce energy and resources and messing up the environment.

[D] The trouble with plastic is that it does not rot. Some environmentalists argue that the only solution to the problem of ever growing mounds of plastic containers is to do away with plastic altogether in the shops, a suggestion unacceptable to many manufacturers who say there is no alternative to their handy plastic packs.

[E] Little research, however, is being carried out on the costs of alternative types of packaging. Just how possible is it, for instance, for local authorities to salvage paper, pulp it and recycle it as egg-boxes Would it be cheaper to plant another forest Paper is the material most used for packaging--20 million paper bags are apparently used in Great Britain each day--but very little is salvaged.

[F] It is evident that more research is needed into the recovery and re use of various materials and into the cost of collecting and recycling containers as opposed to producing new ones. Unnecessary packaging, intended to be used just once, and making things look better so that more people will buy them, is clearly becoming increasingly absurd. But it is not so much a question of doing away with packaging as using it sensibly. What is needed now is a more sophisticated approach to using scarce resources for what is, after all, a relatively unimportant function.

[G] To get a chocolate out of a box requires a considerable amount of unpacking: the box has to be taken out of the paper bag in which it arrived; the cellophane wrapper has to be torn off, the lid opened and the paper removed; the chocolate itself then has to be unwrapped from its own piece of paper. But this insane amount of wrapping is not confined to luxuries. It is now becoming increasingly difficult to buy anything that is not done up in cellophane, polythene or paper.

Order:

45()