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26 tháng 1 2022

Đáp án a) ozone bạn nhé!

18 tháng 11 2021

D.

21 tháng 9 2023

Các đơn chất có trong khí quyển: nitrogen, oxygen, argon, helium, neon, hydrogen,…

Chất được dùng để bơm vào lốp ô tô thay cho không khí là khí nitrogen

Ở những nơi có điều kiện, người ta bơm khí nitrogen vào lốp xe ô tô thay cho không khí vì một số ưu điểm sau:

- Ít bị rò rỉ: Không khí thoát ra khỏi lốp thông qua cấu trúc phân tử của cao su bị kéo giãn khi bánh xe lăn. Nguyên tử nitrogen to hơn so với oxygen, vì vậy ít bị rỉ không khí ra khỏi cao su khiến lốp "non hơi".

- Tiết kiệm nhiên liệu hơn: Vì nitrogen lưu giữ lại trong lốp xe lâu hơn nên giữ áp suất, và giúp tiết kiệm nhiên liệu.

- Giúp điều khiển xe tốt hơn: Áp suât lốp được cần bằng giúp điều khiển xe dễ dàng hơn.

- Giảm hao mòn: Không khí thông thường sẽ chứa hơi nước làm rỉ sét bên trong bánh xe hoặc thân van, khi bơm nitrogen sẽ giảm thiểu được điều này.

Hydrogen: H

Helium: He

Carbon: C

Nitơ: N

Oxygen: O

Natri: Na

31 tháng 3 2020

A. Consists

31 tháng 3 2020

11/ Water _________of hydrogen and oxygen. *

A. consists

B. consist C. is consisted D. is consisting

13 tháng 2 2023

\(PTK\left(SO_2\right)=32\cdot16\cdot2=64\left(amu\right)\\ PTK\left(CO_2\right)=12\cdot16\cdot2=44\left(amu\right)\\ PTK\left(CH_4\right)=12+4=16\left(amu\right)\\ PTK\left(NH_3\right)=14+3=17\left(amu\right)\\ PTK\left(O_2\right)=16\cdot2=32\left(amu\right)\\ PTK\left(N_2\right)=14\cdot2=28\left(amu\right)\\ PTK\left(HCl\right)=1+35,5=36,5\left(amu\right)\\ PTK\left(Cl_2\right)=35,5\cdot2=71\left(amu\right)\\ PTK\left(NaCl\right)=23+35,5=58,8\left(amu\right)\)

X Read the passage. Answer the questions below. Scientists have discovered that the ozone layer is getting thinner. Some predict that the sun’s rays will cause a sharp increase in deaths from skin cancer over the next fifty years. These harmful rays can also damage the eyes, create wrinkles, and cause other health problems. ​The stratosphere contains a form of oxygen called ozone. Ozone is a molecule composed of three oxygen atoms. The chemical formula of ozone is 03. Oxygen molecules make...
Đọc tiếp

X Read the passage. Answer the questions below.

Scientists have discovered that the ozone layer is getting thinner. Some predict that the sun’s rays will cause a sharp increase in deaths from skin cancer over the next fifty years. These harmful rays can also damage the eyes, create wrinkles, and cause other health problems.

​The stratosphere contains a form of oxygen called ozone. Ozone is a molecule composed of three oxygen atoms. The chemical formula of ozone is 03. Oxygen molecules make up about 21% of all gases in the Earth’s atmosphere. They consist of two atoms of oxygen and are labeled 02. Most ozone found in our atmosphere is formed by an interaction between oxygen molecules and ultraviolet radiation (UV) from the sun. When ultraviolet radiation hits an oxygen molecule, it may cause the molecule to break apart into single atoms of oxygen. These single atoms are very reactive, and a single oxygen atom can combine with a molecule of oxygen to form ozone.

​1.​What do people say about the rate of deaths from skin cancer in the future?​

​2. ​How many oxygen atoms are there in a molecule?​

​3.​What elements participate in the formation process of ozone?​

​4.​What happens when an oxygen molecule and an ultraviolet radiation hit each other?

​​​​5.​What is the feature of single atoms?

1
3 tháng 2 2020

X Read the passage. Answer the questions below.

Scientists have discovered that the ozone layer is getting thinner. Some predict that the sun’s rays will cause a sharp increase in deaths from skin cancer over the next fifty years. These harmful rays can also damage the eyes, create wrinkles, and cause other health problems.

​The stratosphere contains a form of oxygen called ozone. Ozone is a molecule composed of three oxygen atoms. The chemical formula of ozone is 03. Oxygen molecules make up about 21% of all gases in the Earth’s atmosphere. They consist of two atoms of oxygen and are labeled 02. Most ozone found in our atmosphere is formed by an interaction between oxygen molecules and ultraviolet radiation (UV) from the sun. When ultraviolet radiation hits an oxygen molecule, it may cause the molecule to break apart into single atoms of oxygen. These single atoms are very reactive, and a single oxygen atom can combine with a molecule of oxygen to form ozone.

​1.​What do people say about the rate of deaths from skin cancer in the future?​

=> Some predict that the sun’s rays will cause a sharp increase in deaths from skin cancer over the next fifty years. These harmful rays can also damage the eyes, create wrinkles, and cause other health problems.

​2. ​How many oxygen atoms are there in a molecule?​

=> Oxygen molecules make up about 21% of all gases in the Earth’s atmosphere

​3.​What elements participate in the formation process of ozone?​

=> Most ozone found in our atmosphere is formed by an interaction between oxygen molecules and ultraviolet radiation (UV) from the sun.

​4.​What happens when an oxygen molecule and an ultraviolet radiation hit each other?

=> When ultraviolet radiation hits an oxygen molecule, it may cause the molecule to break apart into single atoms of oxygen

​​​​5.​What is the feature of single atoms?

=> These single atoms are very reactive, and a single oxygen atom can combine with a molecule of oxygen to form ozone.

3 tháng 2 2020

cảm ơn ạ!

19 tháng 2 2023

Nguyên tố hóa học là những nguyên tử có cùng số proton.

QT
Quoc Tran Anh Le
Giáo viên
5 tháng 11 2023

1.Water ______ of hydrogen and oxygen. a. is consisting b. consists c. has consisted d. will consist 2. Don't give the chocolate to Helen. She ______ it. a. hates b. is hating c. has hated d. hated 3. The Sun ______ us heat and light. a. will give b. is giving c. gives d. has given 4. We ______ students, so we ______ to school on weekdays. a. are/ go often b. are/ often go c. are/ have often gone d. have been / are often going 5. Everyday, Peter ______ at 7 o'clock, ______ breakfast, and then...
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1.Water ______ of hydrogen and oxygen. a. is consisting b. consists c. has consisted d. will consist 2. Don't give the chocolate to Helen. She ______ it. a. hates b. is hating c. has hated d. hated 3. The Sun ______ us heat and light. a. will give b. is giving c. gives d. has given 4. We ______ students, so we ______ to school on weekdays. a. are/ go often b. are/ often go c. are/ have often gone d. have been / are often going 5. Everyday, Peter ______ at 7 o'clock, ______ breakfast, and then ______ to work at 7.30. a. has often got / will have/ go b. often gets up/ has/ goes c. is often getting/ having/ goes d. has often got up/ had / went 6. California ______ in the United Kingdom. It ______ in the U.S a. is not/ is b. has not been/ is c. will not be/ will be d. was not/ has been 7. Cats ______ milk, but birds ______. a. like/ do not b. have liked/ have not c. are liking/ are not d. were liking/ were not 8. Everyday, Sarah ______ her children to school and then ______ home to prepare lunch. a. is taking/ returning b. takes/ returns c. has taken/ returned d. will take/ will return 9. The Sun ______ the ball of fire in the sky that the Earth ______ round. a. will be/ has gone b. will be/ will be going c. is/ goes d. has been/ is going 10. Sally ______ really hard for her exams this week a. takes b. will be taking c. is taking d. had taken 11. Many people ______ living in Seattle because it ______ continually. a. are hating/ is often raining b. have hated/ will often rain c. hate/ often rains d. hated/ was often raining 12. The Sun ______ in the East and ______ in the West. a. rises/ sets b. is rising c. has risen d. will rise/ will set 13. ______ on the computer now? a. Is Peter working? b. Was Peter working c. Has Peter worked d. Will Peter be working 14. Listen! Mr. Jones ______ the piano. You ______ noise. a. is playing/ should not make b. plays/ will not make c. has played/ do not make d. played/ would not make 15. Right now, Long ______ with his friends. They ______ the differences between Bristish English and American English. a. sits/ discuss b. has been sitting/ will discuss c. was sitting/ was discussing d. is sitting/ are discussing 16. A: ______ free this afternoon? B: No, I ______. A: What ______? B: I ______ my dentist a. will you be/ will not/ have you done/ have seen b. Have you been/ have not/ will you do/ will see c. Are you/ am not/ do you do/ see d. Are you/ am not/ are you doing/ am seeing 17. Listen! Someone ______ at the door. I ______ it. a. knocks/ answer b. has knocked/ will be answering c. was knocking/ answered d. is knocking/ will answer 18. Everyday, John ______ rice and vegetables for lunch, but today he ______ chicken soup and roast beef. Today is his brother's wedding. a. has/ is having b. has/ has had c. is having/ has d. has had/ has 19. It ______, so we can't go to the beach a. had rained b. rained c. is raining d. will have rained 20. My father ______ complete silence when he ______ a. is wanting/ works b. wants/ is working c. has wanted/ worked d. had wanted/ was working 21. Since 2003 they ______ their son every year. a. visited b. have visited c. visit d. will visit 22. Usually, Mr. Pile ______ us Physics but today he ______ill, so Mrs. Young ______ us a. teaches/ is/ is teaching b. has taught/ is / teaches c. is teaching/ has been/ teaches d. taught/ was/ was teaching 23. I am sorry I can't hear what you ______ because everybody ______ so loudly. a. are saying/ will talk b. was saying/ has talked c. have just said/ is talking d. said/ was talking 24. I ______ the same car for more than ten years. I ______ about buying a new one. a. have had/ am thinking b. will have/ think c. had/ will think d. am going to have/ was thinking 25. My best friend and I ______ each other for over fifteen years. We still ______ together once a week. a. were knowing/ got b. knew/ have got c. have known/ get d. had known/ are getting 26. The secretary ______ on the report for more than three hours. She hopes she may finish it by the lunch time. a. is working b. will be working c. has been working d. had been working 27. Please turn off the stove. The water ______ for more than fifteen minutes. a. is boiling b. was boiling c. has been boiling d. will be boiling 28. In the 19th century, it ______ two or three months to cross North America by covered wagon. The trip _____ very rough and often dangerous.. a. took/was b. had taken/ had been c. took/ had been d. had taken/ was 29. My grandfather ______ a very exciting life. When he was young, he ______ on the farm in the country, where there ______ a lot of cattle and meadows. a. has/ has lived/ have been b. had/ lived/ were c. was having/ had lived/ had been d. has had/ is living/ are 30. Mary _____ on the essay for two hours now and she _____ that she _____ it in one more hour. a. is working/ has hoped/ can finish b. has been working/ hopes/ will finish c. will have worked/ hopes/ finishes d. had been working/ hoped/ would finish 31. I ______ there once a long time ago and ______ back since. a. went/ have not been b. have gone/ will not be c. was going/ am not d. had gone/ was not 32. Those drivers ______ for three hours when a heavy storm suddenly ______ a. were driving / broke b. drove/ was breaking c. had driven/ was breaking d. had been driving/ broke 33. I ______ to visit you yesterday, but you ______ at home. a. have come/ are not b. had come/ were not c. came/ were not d. was coming/ have not been 34. What ______ when the accident ______ ? a. have you been doing/ occurs b. are you doing/ will occur c. will you be doing/ has occurred d. were you doing/ occurred 35. We ______ TV when it ______ to rain a. are watching/ will start b. have watched/ will be starting c. had watched/ was starting d. were watching/ started 36. I ______ a mystery movie on TV when the electricity ______. a. will be watching / is going b. watched/ was going c. was watching/ went d. have watching/ goes 37. While the doctor ______ Mr. Jones, his son ______ outside this morning a. was examining/ was waiting b. will be examining/ are waiting c. had been examining/ was waiting d. are examining/ is going to wait 38. When the boss____ into the office, his secretary ____, and the accountant ______ on the phones a. was walking/ has been typing/ has been talking b. had walked/ was typing/ had talked c. walked/ was typing/ was talking d. had been walking/ had typed/ talked 39. The guard ______ to his Ipod, so he ______ the fire alarm. a. had listened/ was not hearing b. was listening/ did not hear c. listened/ had not heard d. was listening/ was not hearing 40. The Titanic ______ the Atlantic when it ______ an iceberg. a. was crossing/ struck b. crossed/ was striking c. had crossed/ was striking d. crossed/had struck 41. We were late because we had some car problems. By the time we ______ to the train station, Susan ______ for us for more than two hours. a. got/ had been waiting b. had got/ were waiting c. had been getting/ waited d. were getting/ waited 42. Mike ______ to sit down because he ______ all day at work a. had been wanting/ was standing b. had wanted/ stood c. wanted/ had been standing d. was wanting/ had stood 43. The motorcycle ______ to George for years before Tina ______ it last week. a. belonged/ had bought b. was belonging/ had bought c. had belonged/ bought d. had been belonging/ bought 44. No matter what ______ next, I ______ you. a. will happen/ support b. happened/ would have supported c. happens/ will support d. is happening/ have supported 45. Wait a minute. I ______ this box for you. a. am carrying b. will carry c. carry d. am going to carry 46. I ______ he ______. a. do not think/ will come b. am not thinking/ will come c. have not thought/ comes d. will not think/ comes 47. At this time tommorrow, Peter ______ for the graduation examination, so now he ______ very nervous although he ______ hard for more than 3 years. a. will sit/ has been feeling/ was learning b. will be sitting/ feels/ has been learning c. sits/ will feel/ is learning d. will have sat/ is feeling/ learns 48. By this time next summer, you ______ your studies and ______ a job a. will be completing/ will find b. had completed/ would find c. have completed/ find d. will have completed/ found 49. By the time I ______ to the office, the meeting ______ without me. My boss ______ furious me and I ______. a. will get/ begins/ is/ am fired b. am getting/ will begin/ is going to be/ will be fired c. got/ had already begun/ was/ was fired d. have got/ began/ has been/ am firing 50. By the time he ______ next month, he ______ for our company for ten years. a. retires/ will have been working b. will retire/ has been working c. has retired/ is working d. would retired/ was working 51. Look! There are a lot of clouds. It ______ soon a. is going to rain b. has been raining c. will be raining d. will have rained 52. I am busy. I think I ______ my driving test this week. a. have not taken b. am not going to take c. will have not taken d. do not take 53. A: I called you last night after dinner, but you were not there. Where ______? B: I ______ overtime at the fitness center. a. has you been/ had worked b. were you/ have worked c. were you/ was working d. you were/ worked 54. For the last hundred years, travelling ______ much easier and very comfortable. Now you ______ from New York to Los Angeles in a matter of hours. a. becomes/ fly b. had become/ flew c. will have become/ will fly d. has become/ can fly 55. John ______ for his girlfriend for two hours but she ______. At last, he ______ to the movie without her. a. has been waiting/ does not come/ has gone b. will wait/ has not come/ will go c. is waiting/ will not come/ is going d. had been waiting/ did not come/ went 56. By the time we ______ the letter, Tom ______ for Paris. a. receive/ will have left b. had received/ left c. have received/ will left d. received/ leaves 57. By this time tomorrow, we ______ on the beach of Hawaii where we ______ before. a. are going to lie/ are never b. have been lying/ will never be c. will be lying/ have never been d. are lying/ were never 58. After the boy ______ that the wallet full of money, he ______ to the police and ______ it in. a. will find/ immediately goes/ turns b. has found/ will immediately go/ turn c. was finding/ went/ would return d. had found/ immediately went/ turned 59. Sandy ______ TV in the living room at the moment. At this time yesterday, she ______ television. That is all she ______ doing the most. a. watches/ also watched/ is enjoying b. is watching/ was also watching/ enjoys c. is going to watch/ has also watched/ has enjoyed d. will be watching/ had also watched/ will enjoy 60. Jeans which ______ by Levis Strauss in 1850 ______ one of the most popular kinds of clothes in our present time. a. are first made/ have been b. were first made/ were c. were first made/ are d. had been made/ would be 61. He ______ his boss at this time tomorrow a. is meeting b. has met c. was meeting d. will be meeting 62. A: How much is this book? B: $10 A: OK. I ______ it a. will take b. take c. have taken d. took 63. What ______ since 8 a.m up to now? a. you have been doing b. have you been doing c. have been you doing d. have been doing you 64. Computers ______ in use since 1946. a. are b. were c. have been d. had been 65. ______ to Paris before? a. Are you ever b. Have you been c. Will you ever be d. Had you ever been 66. Mr Pike ______ lunch at home with his wife, but today he ______ lunch with his friends. Mrs. Pike ______ to London since two days ago. a. is usually having/ has/ went b. has usually had/ has/ is going c. usually has/ is having/ has gone d. will have/ has had/ goes 67. John ______ a lot. In fact, when he ______ only two years old, he first ______ to the USA. a. always travels/ was/ has flown b. has always travelled/ was/ flew c. is always travelling/ had been/ flew d. always travelled/ was/ has flown 68. Before we ______ a computer, we ______ that typewriter to type our assignments. a. bought/ have used b. are buying/ use c. buy/ have used d. bought/ had used 69. John ______ in France, but his parents ______ in Cologne, Germany after living there for five years. a. was born/ had met b. had been born/ met c. has been born/ meet d. is born/ have met 70. We ______ each other one day while John ______ a book in the library and I ______ down beside him. a. met/ was reading/ sat b. had met/ was reading/ had set c. meet/ is reading/ have sat d. will meet/ reads/ sat 71. John ______ his parents in France at the moment. He ______ in New York, but ______ his parents for the past few weeks. a. was visiting/ live/ had visited b. has visited/ lived/ is visiting c. is visiting/ lives/ has been visiting d. has been visiting/ had live/ has been visiting 72. A: ______ to come over for dinner tonight? B: Oh, I'm sorry, I can't. I ______ to a movie tonight with some friends. a. Have you wanted/ will go b. Did you want/ went c. Do you want/ am going d. Are you wanting/ go 73. He ______ a good day until a thief ______ into his apartment, ______ all his money, and ______ him up. a. has been having/ comes/ takes/ tied b. had been having/ came/ took/ tied c. was having/ had came/ took/ tied d. is having/ is coming/ has take/ ties 74. A: Where ______ on holiday? B: I don't know. We ______ yet. a. will you go/ are not going to decide b. are you going/ have not decided c. have you gone/ do not decide d. did you go/ had not decided. 75. When I ______ the street, I ______ somebody call my name. a. have crossed/ hear b. had crossed/ would hear c. am crossing/ will hear d. was crossing/ heard 76. The train ______at 8.58, so we ______ in Scotland by lunchtime. a. leaves/ will be b. left/ have been c. has left/ were d. left/ had been 77. I think by the time we ______there, Jim ______. a. get/ will have left b. got/ has left c. will get/ will leave d. had got/ left 78. I ______ the time when I ______ as a teacher. a. have never forgot/have first worked b. am never forgetting/ first work c. will never forget/ first worked d. had never forgot/ was first working 79. Women ______ in presidental elections since 1921. a. vote b. have voted c. had voted d. are voting 80. By the time the boss ______ at 9.00, his employees ______ for two hours. a. will arrive/ are working b. arrives/ will have been working c. arrived/ have been working d. has arrived/ were working 81. - I am hungry. I ______ lunch yet. - Don't worry. I ______ you a sandwich. a. have not had/ will get b. do not have/ am going to get c. will not have/ have got d. am not having/ get 82. Do you think everything ______ when we ______ from the store? a. will be finished/ get back b. is finished/ will get back c. is going to finish/ are getting back d. has been finished/ will have got back. 83. Look! Mary ______a beautiful new dress. She ______ so pretty in the dress. a. was wearing/ looked b. wears/ has looked c. has been wearing/ is looking d. is wearing/ looks 84. I am sick of rain and bad weather! Hopefully, when we ______ up tomorrow morning, the sun ______. a. will wake/ will shine b. are waking/ shines c. are going to wake/ is shining d. wake/ will be shining 85. When the president ______ off the plane, the crowd ______ for him for half an hour. a. gets/ will wait b. got/ had been waiting c. had got/ was waiting d. has got/ will be waiting 86. Jane ______ at my house when you ______. a. is/ will arrive b. will be/ will arrive c. will be/ arrive d. is/ are going to arrive 87. They ______ here for three years before you ______ last week. a. have worked/ came b. have been working/ come c. was working/ had come d. had been working/ came 88. These students ______ hard since the beginning of the school year because they ______ their graduation exam next May. a. studied/ are going to take b. are studying/ will be taking c. study/ will have taken d. have been studying/ will take 89. The students ______ chapter 5 next week, so they ______ to prepare for it now. a. have studied/ will read b. are studying/ have read c. will study/ read d. will be studying/ are reading 90. By the time John ______ to help, we ______ the work. a. comes/ finished b. comes/ will have finished c. will come/ will have d. came/ have finished 91. Mary sometimes ______ to turn off the computer before she ______ home. a. forgot/ had gone b. has forgot/ is going c. is forgetting/ has gone d. forgets/ goes 92. They ______ good preparations before they ______ their final examination yesterday. a. made/ had taken b. had made/ took c. have made/ take d. will have made/ have taken 93. He ______ a birthday party tomorrow for his daughter who ______ three. a. is having/ turns b. will have had/ will turn c. is going to have/ has turned d. has had/ is going to turn 94. When Susan ______ yesterday, Peter ______ dinner. He ______ cooking very much and often ______ the meals himself a. phoned/ was cooking/ likes/ prepares b. had phoned/ cooked/ liked/ prepared c. was phoning/ was cooking/ has liked/ is preparing d. has phoned/ is cooking/ is liking/ preparing 95. They ______ to finish their work because they ______ Los Angeles next Sundays. a. are needing/ visit b. need/ are going to visit c. have needed/ are visiting d. needed/ have visited 96. At present, Mary ______ her clothes. She ______ the clothes on Sundays. a. is washing/ often washes b. was washing/ hhas often washed c. has washed/ is often washing d. washes/ often washed 97. I ______ that movie before last night. a. did not see b. has not seen c. had not seen d. will see 98. I ______ Lisa at the museum when I ______ to restaurant but she ______ me. a. was seeing/ was going/ had not seen b. had seen/ went/ was not seeing c. have seen/ have gone/ does not see d. saw/ was going/ did not see

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