题干

在“用油膜法估测分子的大小”的实验中,把1滴油酸酒精溶液滴人盛水的浅盘内,让油膜在水面上尽可能散开,已知这滴油酸酒精溶液中油酸的体积为7×10﹣6mL测得油酸薄膜的轮廓形状和尺寸如图所示,图中正方形方格的边长为1cm,试求.

①油酸膜的面积是____cm2

②实验测出油酸分子的直径是____m(保留一位有效数字)

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答案(点此获取答案解析)

120,6×10﹣10m

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   If you think English means endless new words, difficult grammar and sometimes strange pronunciation, you are wrong. Haven’t you noticed that you have become smarter since you started to learn a language?
   According to a new study by a British university, learning a second language can lead to an increase in your brain power. Researchers found that learning other languages changes grey matter. This is the area of the brain which processes information. It is similar to the way that exercise builds muscles.
   The researchers also found the effect is greater on the younger people who learn a second language.
   A team led by Dr. Andrea Mechelli, from University College London, took a group of Britons who only spoke English. They were compared with a group of “early bilinguals(通两种语言的人)”, who had learnt a second language before the age of five, as well as a number of later learners.
   Scans showed that grey matter density(密度)in the brain was greater in bilinguals than in people without___________________. But the longer a person waited before mastering a new language, the smaller the difference was.
   “Our findings suggest that the structure of the brain is changed by the experience of learning a second language,” said the scientists.
It means that the change itself increases the ability to learn.
   Professor Dylan Vaughan Jones of the University of Wales, has researched the link between bilingualism and maths skills. Having two languages gives you two windows on the world and makes the brain more flexible,” he said, “You are actually going beyond language and have a better understanding of different ideas.”