问题 选择题

有关阳离子交换膜电解饱和食盐水的(装置如图)说法错误的是

A.转移电子0.8 mol时产生氢气8.96 L(标准状况)

B.从出口B处导出的是氢氧化钠与氯化钠的混合溶液

C.装置中出口①处的物质是氯气,出口②处的物质是氢气

D.装置中的阳离子交换膜只能让阳离子通过,不能让阴离子通过

答案

答案:B

题目分析:A、转移电子0.8 mol时产生氢气的量为0.8÷2×22.4="8.96" L,正确;B、交换膜只能通过阳离子,氯离子不能通过,故出口B导出的是氢氧化钠溶液,错误;C、阳极氯离子失去电子,生成氯气,阴极氢离子得到电子生成氢气,正确;D、正确。

问答题 简答题
单项选择题

The number of speakers of English in Shakespeare’s time is estimated to have been about five million. Today it is estimated that some 260 million people speak it as a native language, mainly in the United States, Canada, Great Britain, Ireland, South Africa, Australia and New Zealand. In addition to the standard varieties of English found in these areas, there are a great many regional and social varieties of the language as well as various levels of usage that are employed both in its spoken and written forms.

In fact, it is impossible to estimate the number of people in the world who have acquired an adequate working knowledge of English in addition to their own languages. The purpose for English learning and the situations in which such learning takes place are so varied that it is difficult to explain and still more difficult to judge what forms an adequate working knowledge for each situation.

The main reason for the widespread demand for English is its present-day importance as a world language. Besides serving the indefinite needs of its native speakers, English is a language in which some of important works in science, technology, and other fields are being produced, and not always by native speakers. It is widely used for such purposes as meteorological and airport communications, international conferences, and the spread of information over the radio and television networks of many nations. It is a language of wider communication for a number of developing countries, especially former British colonies. Many of these countries have multilingual populations and need a language for internal communication in such matters as government, commerce, industry, law and education as well as for international communication and for entrance to the scientific and technological developments in the West.

Which of the following statements is NOT true()

A. Some 260 million people in the world have an adequate working knowledge of English.

B. There are some 260 million native speakers of English in the world.

C. It is almost impossible to estimate the number of people with an adequate working knowledge of English.

D. People learn English for a variety of reasons.