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Определить массовую долю аминоэтановой кислоты ,если с 400 г её раствора прореагировало 30 мл 95% этанола с плотностью 0,9 2/мл.
Ответы 1
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Масса этанола: 30мл*0.92г/мл=27.6г 27.6г*0.95=26.22гАминоэтановая кислота х ------ Этанол 26.22г 75г/моль-------46г/моль х=42.75г (42.75/400)*100=11%
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Автор:
nicomedes - 5 лет назад
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§ 1. There used to be a general feeling that computer games were bad for you. and books were good. Now people are not so sure. Researchers have found that computer games, television and the Internet have become key factors in boosting children's IQs up to levels never reached by past generations.
§ 2. The idea that intelligence can be measured was first suggested about a century ago, but at that time it was hard to find tests that gave useful results. Over the past two decades, however, tests have become more complex and researchers have found that IQ scores can give a good indication of what children's future exam results will be. Some experts have even claimed that IQ scores can accurately predict what level of income and status young people will achieve in adult life.
§ 3. Why are today's youngsters doing so much better than their grandparents? Of course, better nutrition, higher standards of living and improved education all play their part in raising general levels of intelligence. But there seems to be more to it than that. Scientists are attributing the change in intelligence levels to the complexity of modern life.
§ 4. In today's fast-moving world, young people are required to interact constantly with electronic gadgets and equipment. This is developing youngsters' brains in ways that older generations never experienced. Computers are one-of the major sources of stimulation, and activities such as playing games and using the Internet seem to be particularly important.
§ 5. There are still some things that remain unexplained, however. For example, the increase in children's IQ scores varies according to the type of intelligence being tested. It appears that nowadays people are better at abstract thinking than their ancestors were — but their verbal and mathematical abilities have remained the same as those of previous generations. No one knows why this is the case. Nevertheless, during the last few years there has certainly been a general upward trend, and it has been found that the present generation have IQs about 15 points above their parents.
§ 6. It has been claimed that, in moderation, computer gaming is positively good for youngsters. It requires positive qualities such as determination, fast thinking and rapid learning. However, it seems that improvements in IQ may not last very long without continuing stimulation. The brain seems to be like a muscle and requires repeated and vigorous exercise to stay fit and healthy. When it comes to IQ, it's a case of 'Use it or lose it'.
A36. In the first paragraph, the writer says that computer games
1.are not as good for children as reading.
2.can improve the intelligence of young people.
3.are now used in many different ways by children.
A37. According to the article, in the last twenty years IQ tests have become
1.a substitute for examinations.
2.a way of increasing young people's income.
3.more reliable than they used to be.
A38. What does the writer say about young people and electronic equipment nowadays?
1.The equipment makes things too easy for them.
2.The equipment is an important part of their daily lives.
3.They depend on the equipment for their entertainment.
A39. According to the writer, what remains unexplained about children's intelligence?
1.why levels of some types of intelligence have remained unchanged
2.how the improvement in intelligence levels can lie continued
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