问题 填空题

下列说法中正确的是_________ 。(选对一个给3分,选对两个给 4分,选对3个给6分。每选错一个扣3分,最低得分为0分)

A.一定量气体膨胀对外做功100 J,同时从外界吸收120 J的热量,则它的内能增大20 J

B.在使两个分子间的距离由很远(r > 10-9 m)减小到很难再靠近的过程中,分子间作用力先减小后增大,分子势能不断增大

C.由于液体表面层分子间距离大于液体内部分子间距离,液体表面存在张力

D.用油膜法测出油分子的直径后,要测定阿伏加德罗常数,只需再知道油的密度即可E.空气相对湿度越大时,空气中水蒸气压强越接近同温度水的饱和气压,水蒸发越慢

答案

ACE

题目分析:根据符号法则知:一定量气体膨胀对外做功100 J,功为负值,从外界吸收120 J的热量,热量为负值,即,根据热力学第一定律知:,故A正确;两分子从很远不断靠近,直到不能靠近的过程中,分子间的作用力开始为引力,先变大后变小,当分子间距离等于时分子力为零,当分子间的距离小于时,分子间作用力为斥力,分子力逐渐变大.开始时分子之间距离大于,分子力为引力,分子相互靠近时分子力做正功,分子势能减小,当分子之间距离小于时,分子力为斥力,再相互靠近过程中分子力做负功,分子势能增大,所以分子势能先减小后增大,故B错误;在液体内部分子间的距离在左右,而在表面层,分子比较稀疏,分子间距离大于,因此在液体表面分子间的作用表现为相互吸引,它的作用使液体表面绷紧,所以液体表面存在张力,故C正确;由知,用油膜法测出分子直径后,要测阿伏伽德罗常数需要知道油的摩尔体积,知道油的密度求不出阿伏伽德罗常数,故D错误;空气相对湿度是指空气中水汽压与饱和汽压的百分比,在同样多的水蒸气的情况下温度降低相对湿度就会升高,当空气相对湿度越大时,空气中水蒸气压强越接近同温度水的饱和气压,水蒸发越慢,故E正确。所以选ACE。

选择题
单项选择题

Seven years ago, a group of female scientists at the Massachusetts Institute of Technology produced a piece of research showing that senior women professors in the institute’s school of science had lower salaries and received fewer resources for research than their male counterparts did. Discrimination against female scientists has cropped up elsewhere. One study—conducted in Sweden, of all places—showed that female medical-research scientists had to be twice as good as men to win research grants. These pieces of work, though, were relatively small-scale. Now, a much larger study has found that discrimination plays a role in the pay gap between male and female scientists at British universities.

Sara Connolly, a researcher at the University of East Anglia’s school of economics, has been analyzing the results of a survey of over 7,000 scientists and she has just presented her findings at this year’s meeting of the British Association for the Advancement of Science in Norwich. She found that the average pay gap between male and female academics working in science, engineering and technology is around £ 1,500 ($2,850) a year.

That is not, of course, irrefutable proof of discrimination. An alternative hypothesis is that the courses of men’s and women’s lives mean the gap is caused by something else; women taking "career breaks" to have children, for example, and thus rising more slowly through the hierarchy. Unfortunately for that idea, Dr. Connolly found that men are also likely to earn more within any given grade of the hierarchy. Male professors, for example, earn over £ 4,000 a year more than female ones.

To prove the point beyond doubt, Dr. Connolly worked out how much of the overall pay differential was explained by differences such as seniority, experience and age, and how much was unexplained, and therefore suggestive of discrimination. Explicable differences amounted to 77% of the overall pay gap between the sexes. That still left a substantial 23% gap in pay, which Dr. Connolly attributes to discrimination.

Besides pay, her study also looked at the " glass-ceiling" effect—namely that at all stages of a woman’s career she is less likely than her male colleagues to be promoted. Between postdoctoral and lecturer level, men are more likely to be promoted than women are, by a factor of between 1.04 and 2.45. Such differences are bigger at higher grades, with the hardest move of all being for a woman to settle into a professorial chair.

Of course, it might be that, at each grade, men do more work than women, to make themselves more eligible for promotion. But that explanation, too, seems to be wrong. Unlike the previous studies, Dr. Connolly’s compared the experience of scientists in universities with that of those in other sorts of laboratory. It turns out that female academic researchers face more barriers to promotion, and have a wider gap between their pay and that of their male counterparts, than do their sisters in industry or research institutes independent of universities. Private enterprise, in other words, delivers more equality than the supposedly egalitarian world of academia does.

In contrast to Dr. Connolly’s study, the previous ones failed to()

A. make a comparison between the experience of scientists in others kinds of laboratory and that of those in universities

B. make themselves more eligible for promotion

C. make a difference for a woman to settle into a professorial chair

D. make the supposedly egalitarian world of academia deliver more equality