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1/ Cho 7,5 gam hỗn hợp X gồm Al và Mg tác dụng hoàn toàn với dung dịch HCl 2M thì thu được 7,84 lít khí ở (đktc) a) Tính thể tích dung dịch HCl đã phản ứng biết rằng HCl đã dùng dư 10% so với lượng cần thiết b) Cô cạn dung dịch sau phản ứng thu được m (g) muối khan. Tính giá trị của m (g) 2/ Để hòa tan hoàn toàn hỗn hợp gồm Zn và ZnO người ta phải dùng vừa hết 600ml dung dịch 1M và thu được 4,48 lít khí ( đktc) Xác định khối lượng Zn và ZnO trong hỗn hợp ban đầu
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Exercise 1. Read the following passage and mark the letter A, B, C, or D to indicate the correct answer to each of the questions. The Amazon rainforest is home to more than a third of all the world's species of plants, birds and animals. Twenty per cent of all the birds in the world live in the rainforest. Scientists have discovered thousands of types of plants and animals that can only be found there. There are thousands - probably millions more that we haven't discovered yet. There are at least 2.5 million species of insects there. Imagine what would happen if they all lost their home? It couldn't happen, could it? Unfortunately, it's happening right now. Yet, the rainforest is big. But it's getting smaller. The problem is that people are cutting down the trees, mainly to make room for cows. These provide meat and make money for their owners. This process of cutting down trees is called ‘deforestation'. The good news is that it is slowing down. In 2004, for example, more than 27,000 square kilometres were cut down. That's an area bigger than Wales. In 2006, because of all the campaigns to save rainforest, it dropped to just over 13,000 square kilometres. The bad news is that it's not enough. Scientists predict that by 2030, the rainforest will have become smaller by 40%. It's possible that by the end of the 21st century, the rainforest will have completely disappeared. With deforestation, thousands of the animals, birds, fish and plants that live in the Amazon rainforest lose their home, their natural habitat. Some of them move to other areas, but most of them die. Many species have already become extinct, and many more will if deforestation continues. That will change the balance of life in the rainforest and could cause enormous problems to the region's ecosystem. There's another problem too. Trees and plants are a vital source of oxygen. If we cut them down, we lose that oxygen. But it's worse than just that. With deforestation, the trees and plants are burnt. This sends gases into the Earth's atmosphere, which stops some of the Earth's heat escaping. That then leads to the temperature here on the ground going up. This increase in the world's temperature is called 'global warming', and most scientists believe it's a very serious issue. If they stopped deforestation, it might help prevent global warming Question 1: Which title best summarises the main idea of the passage? A. Chances for owners of cow ranches B. Threats to Amazon rainforest C. Global warming effects D. Habitat destruction Dẫn chứng/giai thích:.............................................................. Question 2: According to the passage, which of the following is TRUE? A. A fifth of all the birds in the world live in the rainforest. B. 20% of all the animals in the world live in the rainforest. C. Nearly two million species of insects are found in the Amazon rainforest. D. Nearly half of the world's species of plants grow there. Dẫn chứng/ Giải thích:…………………………………………………………………. Question 3: In paragraph 1, the word "room” is closest in meaning to ____. A. chamber B. flat C. area D. studio Dẫn chứng/ Giải thích:…………………………………………………………………. Question 4: In paragraph 2, the word "it” refers to ____. A. room B. process C. rainforest D. deforestation Dẫn chứng/ Giải thích:…………………………………………………………………. Question 5: According the passage, which of the following is TRUE about Amazon rainforest? A. It has become smaller by 40%. B. The deforestation is decreasing. C. 25% of animal species are extinct now. D. The deforestation is under control. Dẫn chứng/ Giải thích:…………………………………………………………………. .Question 6: In paragraph 2, the word “enormous” is closest in meaning to ____. A. serious B. important C. common D. insignificant Dẫn chứng/ Giải thích:…………………………………………………………………. .Question 7: What might help to restrain global warming? A. increasing deforestation B. stabilising deforestation C. stop cutting down trees D. clearing more trees for farming Dẫn chứng/ Giải thích:…………………………………………………………………. Question 8: In the final paragraph, the word "increase” is closest in meaning to ____. A. rise B. decrease C. degrade D. minify Dẫn chứng/ Giải thích:………………………………………………………………….

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