Cách nhận biết:
Dùng quỳ tím nhúng vào 2 dung dịch.
+ Axit axetic là một loại axit hữu cơ nên làm quỳ tím hóa đỏ.
+ Rượu etylic không làm đổi màu quỳ tím.
-Trích mỗi dd một ít bỏ vào các ống nghiệm riêng biệt, đánh số thứ tự
-Bỏ mẩu quỳ tím vào các ống nghiệm quan sát hiện tượng thấy:
+Ống nghiệm nào thấy quỳ tím hóa đỏ nhận ra axit axetic
+Ống nghiệm nào thấy quỳ tím không đổi màu nhận ra rượu etylic
Giúp dùm mk bài 3b,3c và bài 5b,c,d. Mk hứa sẽ vote 5 sao ạ
Từ 1 tấn xenlulozơ( chứa 40% tạp chất ) a.có thể sản xuất được bao nhiêu kg xenlulozơ trinitrat với hiệu suất phản ứng là 90% b.bao nhiêu kg glucozơ biết hiệu suất quá trình thủy phân là 75% c .bao nhiêu kg cao su buna biết hiệu suất cả quá trình là 60% viết các phản ứng xảy ra
`sqrt(3)tan(theta)-1=0` nhanh lên mn ơi
"Is it difficult to reduce our carbon footprints?" A. It depends on the way you think. B. Not at all. Just practicing the 3R’s. C. It’s not if we still rely on fossil fuels. D. I’m not sure. What will happen?
Vẽ animer or chibi or cali = apppp
1. Children get present ______ Christmas and ______ their birthday. (at … at / on … on / on … at / at … on) 2. If you are going to the post office, would you post a letter ______ me? (to / at / on / for) 3. The windows haven’t been cleaned ______ weeks. (ago / since / for / to) 4. We usually go to our home village at least once ______ the summer. (in / on / to / for) 5. He said that John ______ up his job. (has given / have given / had given / had to give) 6. When I saw Susan, she said she was taking her driving test ______. (today / the next day / tomorrow / the tomorrow) 5 7. My TV is broken. I wish it ______ soon. (would be repaired / is repaired / was repaired / will be repaired) 8. I have lived with my parents. I wish I ______ an apartment. (will have / had / would / has) 9. Have you ever wished you ______ to ski when you were younger? (will learn / could learn / learn / can learn) 10. Sometimes he wishes he ______ a different career when he graduates. (can choose / choose / will choose / could choose) 11. Matthew said he was meeting a friend at the station later ______. (that day / yesterday / tomorrow / this today) 12. The astronauts have already been in orbit ______ two days. (since / for / till / to) 13. We have lunch from 12.00 ____ 1.00. Then we start again go on ______ 5.30. (to … at / from … to / to … to / to … till) 14. She said that she ______ to learn to drive. (is going / go / goes / was going) 15. She asked me ______ I liked pop music. (if / that / what / when) 16. She said that she was going away for a few days and ____ phone me when she got back. (will / must / would / shall) 17. I’ve lived in this street ______. (in 1998 / for 1998 / since 1998 / tomorrow) 18. I want two seats for Romeo and Juliet ______ Friday night. (on / in / at / to) 19. Our train arrived in York ______ 6.00. (in / for / on / at) 20. There was an accident at the crossroads ______ midnight last night. (at / for / on / in) 21. She said she ______ come to the party on Friday. (won’t / doesn’t / can’t / couldn’t) 22. I’m going to swim ______ Monday with Tom. (at / on / for / of) 23. If my watch is broken, I ______ buy a new one because I always need one. (have to / might / have / may) 24. I have got an awful headache. If I see a chemist’s, I _____ buy some aspirins. (must / might / may / should to) 25. I plan to travel around the world. If I don’t visit my father in Japan this year, I ______ go to the USA. (must / have / may / ought to) 26. If you want to get good grades, you ______ study hard. (must / ought / have / have) 27. Let’s wait ______ it stops raining. (until / for / to / since) 28. I have lived in this house ______. (ago six years / in six years / since six years / for six years) 29. Columbus discovered America ______ the 15th century. (in / since / for / on) 30. The course begins ______ 8 am ______ 5 pm. (from … during / from … since / from … to / in … to) 31. I fell asleep ______ the movie. (during / since / from / for) 32. Bill asked where ______ from. (do I come / did I come / I come / I came) 33. He wonders what ______ with my heavy luggage. (I will do / I would do / will I do / I do) 6 34. He said that he was coming ______. (tomorrow after / yesterday / the next day / following day) 35. You ______ go to university if you want to study medicine. (has to / will / must / ought) 36. If you want to loose weight, you ______ eat too many sweets. (might not / mustn’t / shouldn’t / may not) 37. She wishes she ______ a new bicycle. (can have / will have / has / could have) 38. I ______ it ______ rain so much in this city. (wishes … didn’t / wish … didn’t / wished … don’t / wish … don’t) 39. If you want to get well, you ______ see a doctor. (must / might / may / ought) 40. ______ you ever wish you ______ fly? (Did ... could / Do … could / Do … can / Did … can) 41. If he doesn’t come soon, he ______ be late. (has / ought to / ought / might) 42. I wish I ______ on a beautiful sunny beach now. (would be lying / can be lying / can be lied / could be lying) 43. ______ he will change his job if he go to the USA. (Perhaps / Since / Recently / Lately) 44. He ______ someone ______ answer that telephone. It’s been ringing for about five minutes. (wish … can / wish … would / wishes … can / wishes … would) 45. If the kitchen is in a mess, you ______ clean it. (will / might / ought to / may) 46. I wish you ______ so fast. It makes me nervous. (weren’t driving / can’t drive / won’t drive / will not drive) 47. The music next door is very loud. I wish they ______. (would turn it down / can turn down it / will turn it down / turn down it) 48. He will stay there ______ the beginning of the October. (for / to / until / on) 49. ______ afternoon, he feeds the chickens and collects their eggs. (The / In the / At / On) 50. What are you doing ______ weekend? (till this / the / in this / this)
Câu c d thôi nha mn mong mn giúp đỡ
vẽ cali=appppppppppppppppppppppppppppppppppp Chữ j cx đc
Tím số nguyên tố để p+6,p+8,p+12,p+14 đếu là số nguyên tố
Vẽ đám mâyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy
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