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Học tại trường Chưa có thông tin
Đến từ Chưa có thông tin , Chưa có thông tin
Số lượng câu hỏi 16
Số lượng câu trả lời 0
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Chủ đề:

Bài 5: Cấu tạo bảng tuần hoàn các nguyên tố hoá học

Câu hỏi:

Trong tự nhiên copper (Cu) có hai đồng vị là 63Cu và 65Cu tương ứng với tỉ lệ số nguyên tử là 3:1. Tính khối lượng của 63Cu có trong 13,45 gam CuCl2. Cho nguyên tử khối trung bình của chlorine là 35,5 và xem nguyên tử khối mỗi đồng vị có giá trị bằng số khối.
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Chủ đề:

Bài 5: Cấu tạo bảng tuần hoàn các nguyên tố hoá học

Câu hỏi:

Nguyên tử khối của Brôm là 79,91. Brôm có hai đồng vị 7935Br3579Br và 8135Br3581Br.

(1). Tính % mỗi loại đồng vị trong tự nhiên : .......................................................

(2). % khối lượng của mỗi loại đồng vị: ............................................................

(3). Số đồng vị 79Br79Br là 700 thì số đồng vị còn lại là: ...............................
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Chủ đề:

Bài 1: Bất phương trình bậc nhất hai ẩn

Câu hỏi:

Biểu diễn miền nghiệm của các bất phương trình sau:
a) x−2y−1>0;x−2y−1>0;

x+y−1≤0.x+y−1≤0.
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tính khối lượng bằng amu và bằng gam của 1 nguyên tử Fe (26p,30n)
                                                                      2 nguyên tử Al (13p,14n)
                                                                     4 nguyên tử P ( 15p,16n)
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1. “You can sit here”. The steward 2. “I’m taking my driving test tomorrow” She 3. “Jim may arrive late today” She 4. “I’ve only had this new computer since yesterday” Johny 5. “I don’t want anything to eat now” He 6. “I posted the card yesterday”. Joanna 7. “You must do your homework every day”. Jane 8. “You should go to the library more often”. Tom 9. “There isn’t any milk in this bottle, Ann”. Mike 10. “John left here an hour ago”. She 11. “The twins can’t go to school today because they’re ill.” Chris 12. “I grow these carrots myself” He 13. “I won’t be home this evening because I have to work late” Peter 14. “I don’t know where Archie is today”. Victoria 15. Nam said to us “I am very happy to see you here”. Nam 16. “What’s your name ?” She 17. “What color are you going to paint the living room?” she asked them. She 18. “How many languages can you speak ?” I asked her 19. “Why do you want to take this course?” She 20. The doctor asked me, “How do you feel now ?” 21. “Where do you live, the boy ?”, asked the man. 22. She asked me, “Why do you have to do this work ?” 23. She asked me : “How old are you ?” 24. He asked Lan, “How far is it from your house to the school ?” 25. “Who puts the salt in my cup of coffee ?”, asked Peter. 26. “Can you speak any other languages ?” She asked 27. “Do you have any French friends ?” She asked 28. He asked me, “Are you free on next Sunday ?” 29. The tourist asked me, “Is there a post office near here ?” 30. “Can you play the piano ?”, he asked the girl. 31. I asked him, “Will you take part in the program with me ?” 32. My teacher asked me “Have you ever heard about UFOs ?” 33. She asked me “Do you like playing games on the Internet ?” 34. They asked him, “Do you like to play this game ?” 35. “Are you a student ?” She asked 36. The teacher said to us : “Copy these exercises in your notebooks” 37. My mother asked me, “Don’t spend much time on playing games” 38. The old woman said to the boy, “Can you help me ?” 39. Mrs Tuyet said to her son, “Give the book to me, please” 40. Maryam said to Lan, “Would you like to come and visit me next summer?” 41. His mother said to him : “Don’t forget to turn off the faucet after using”. 42. Mr Lam asked his secretary, “ Can you choose a suitable language school for me ?” 43. He said to me, “Do this test again, please” 44. The teacher said to them, “Don’t make noise in class” 45. “Can you open your bag, please ?”, the custom officer said to me. 46. Mary said to me, “Can I borrow you some money ? I want to buy this shirt.”
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If you (go) __________ away, please write to me.2. If he (eat) __________ another cake, he will be sick.3. If men (be) __________ only more reasonable, there would be no more war.4. If it is convenient, let’s (meet) __________ at nine o’clock.5. It will be impossible for me to finish my work if you (not cease) __________ this chatter.6. If he (take) __________ my advice, everything can go well.7. He never does his homework. If he (do) __________ his homework, he (not worry) __________ about his examination.8. What you (do) __________ if she refuses your invitation?9. If today (be) __________ Sunday, we (go) __________ to the beach.10. They (make) __________ fewer mistakes if they were more careful.11. Unless they (pass) __________ their examinations, they would join the army.12. You (be) __________ ill if you drink that water.13. If Tom (go) __________ to bed earlier, he would not be so tired.14. If he (try) __________ hard, he’ll pass the examination.15. I could understand the French teacher if she (speak) __________ more slowly.16. If we (invite) __________ her, she might go dancing with us.17. These plants will die if you (not water) __________ regularly.18. If you pass the examination, we (have) __________ a celebration.19. If I (be) __________ you, I would tell him the truth.20. If he (have) __________ much money, he’ll buy a house.
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1. He said: “I shall expect her.”2. Lan said to me: “You are looking much better.”3. He said to me: “Did you see the accident yesterday?”4. John said to me: “How did you come here?”5. Nam said to his father: “Please let me go to Paris.”6. My friend asked me: “Have you had a lot of money?”7. He said: “I can’t meet you here either today or tomorrow.”8. David said: “Don’t forget to give the book to Jane.”9. The foreigner asked me: “Do you know how far the drug store is?”10. Nancy said: “Why didn’t you call me, John?”. Nancy wanted to know
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Although She draws very well, her parents want her to become a nurse.
-> In spite of
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john rarely sees paul although they live in the same town
in spite of->
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