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问题 选择题

下列除去杂质的方法中，不正确的是

选项物质（括号内为杂质）去除杂质的方法
ACu ( Fe )加过量硫酸铜溶液、过滤
BNaCl (泥沙)溶解、过滤、蒸发
CCO (CO2)通过足量浓氢氧化钠溶液，干燥
DNaOH溶液 (Na2CO3)加入适量的稀盐酸、蒸发
 

答案

答案：D

题目分析：根据除杂的原则和物质的性质选择适当的方法和试剂，要求能把杂质除去，同时不要带入新的杂质，原物质的质量不能减少，但可以增加。

A、除去Cu中的Fe：因为铁能置换出硫酸铜中的铜，还可以增加原物质的质量，故加过量硫酸铜溶液、过滤，方法正确；

B、除去NaCl中的泥沙：因为泥沙不溶于水，可采用溶解、过滤、蒸发的方法，方法正确；

C、除去CO中的CO2：根据二氧化碳能与碱溶液反应，而CO不能，故可通过足量浓氢氧化钠溶液，并干燥，方法正确；

D、除去NaOH溶液中的Na2CO3：加入适量的稀盐酸是错误的，因为盐酸和这两种物质都反应，会把原物质也除去。故选D

点评：物质的除杂和净化是中考的重点和热点，同学们要把握住除杂的原则，根据物质的性质来解决此类问题。

选择题

读图l5，回答43～44题。

小题1:代表水土流失、酸雨危害、森林锐减、水体污染的 图例依次是

A．甲、乙、丙、丁

B．乙、甲、丙、丁

C．丙、甲、丁、乙

D．丁、丙、乙、甲小题2:影响全球气候变暖，并直接威胁生物多样性的一类环境问题是

A．甲

B．乙

C．丙

D．丁
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单项选择题

There is a basic hypothesis that the majority of serious motoring offences are derived from accidents, and there is nothing in the offender’s personality or background that predisposes him to break the law. If an accident is a chance event that happens so quickly and suddenly that it is beyond anyone’s control to prevent it, then it is clear that this hypothesis is disproved. For only about 14 per cent of the 653 offences considered in a recent survey could possibly be called inadvertent accidents in this sense, and even this estimate is stretching credulity to its limits. In the great majority of cases the offences were largely of the offenders’ own making. In 11 per cent of the 653 cases and 21 per cent of 43 offenders who were interviewed there was evidence of selfish, and even ruthless, self-interest, but it was not possible to infer personality disturbance in more than 25 per cent of the 653 and 39 per cent of the 43 offenders. Though the inferences with regard to personality traits may be an overestimate in the interpretation of qualitative data, they could equally be an underestimate, since so very little was ever recorded about the offenders themselves. The lack of data is a consequence of the almost total lack of interest in motoring offenders as persons. It must be assumed, therefore, in the absence of evidence to the contrary that the majority of serious motoring offenders considered in the survey were normal people, who succumbed to temptation when circumstances were favourable and it was expedient to take a chance, so perhaps there is something in the normal personality that predisposes a driver to break the law. Whatever it is, its presence is much more evident in males than in females, since the analysis of the national statistics shows a predominance of males over females of between 18:1 and 22:1.
The real significance of these figures is hard to assess, because the relative proportions of each sex at risk are unknown. One research worker produced a ratio of six males to one female from his sample of insurance policy holders, but this is almost certainly an underestimate since many females — probably more than males — are likely to be driving on someone else’s policy. A ration of three to one is probably nearer to the real state of affairs. Females reached noticeable proportions only among the hit-and-run drivers, and there seems to be some justification for calling this the feminine offence. The difference between the sexes in their relative propensity to break the law on the roads is important, because it shows that motoring offenders have a characteristic in common with offenders in other fields of criminal activity, where males predominate to a marked degree. One motor insurance underwriter recently announced his intention to offer discounts on premiums where the policy holder or the named driver was a woman.
The basic hypothesis is further disproved by the very high incidence, among the offences studied, of failing to insure against third-party risks. Yet accidents brought to light only a very small percentage of this kind of crime. Moreover, it could not possibly be said that this, the most common of the serious offences, was brought about by providence. On the contrary, it can be regarded as a typical form of economic crime, which, although sometimes committed through inadvertence, is more usually quite deliberate and calculated.

It can be inferred from the passage that______.

A．(A) women are unwilling to drive on someone else’s policy

B．(B) women are more likely to be the hit-and-run drivers

C．(C) men are regarded as criminals in road accidents

D．(D) men are more likely to be insurance underwriters
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