Đốt cháy 3 g chất hữu cơ A, thu đc 8,8 gam CO2 và 5,4 gam H2O. Biết tỉ khối hơi của A so với khí hidro là 15. Hãy xác định công thức phân tử của A

Cho 8,4 gam một anken x phản ứng vừa đủ với dung dịch brom.thu đc 24,4g sản phẩm cộng.CTPT x là

giúp mình đi mình đang cần gấp giải chi tiết 1 chút

34. That restaurant is so dirty that no one wants to eat there. It is such................................................................................................................................ 35. Tim will be eighteen next week. It's Tim's............................................................................................................. Giúp mình với

Hãy chỉ các lỗi về liên kết nội dung trong các đoạn trích sau và nên cách sửa lỗi ấy. a)(1)Cắm bơi một mình trong đêm. (2)Đêm tối bưng không nhìn rõ mặt đường. (3)Trên con đường ấy, chiếc xe lăn bánh rất êm. (4)Khung xe phía cô gái ngồi lồng đầy bóng trăng. (5)Trăng bồng bềnh nổi lên qua dãy Pú Hồng. (6)Dãy núi này có tính chất quyết định đến gió mùa đông bắc ở nước ta. (7)Nước ta bây giờ là của ta rồi, cuộc đời đã bắt đầu hửng sáng.

Giải phương trình a) (x^2 + 2x +1) - 9 = 0 b) x^3 - 1 = x (x - 1)

Test 1 Ex1 2. They have little money. They are happy (despite) 3. We had planned to walk right round the lake. The heavy rain made this impossible. (although) 4. I got very wet in the rain. I had an umbrella. (although) IV. Choose the word which has a different stress pattern from the others. 1. A. hotel B. chimney C. future D. petrol 2. A. population B. uncomfortable C. overcrowded D. celebration 3. A. peaceful B. wealthy C. diverse D. labour 4. A. direct B. affect C. open D. renew 5. A. succeed B. happen C. replace D. attend 6. A. reward B. country C. samba D. music 7. A. helicopter B. entertainment C. superstitious D. documentary 8. A. perform B. order C. receive D. rehearse V.Complete the following passage by choosing the best option, A, B, C or D. Energy is very important in our modern life. People use energy (1)__________ transportation, cooking, heating and cooling rooms, manufacturing, lighting, and entertainment. (2) ________ energy nowadays comes from fossil fuels – petroleum, coal, and natural gas. (3) ________, burning fossil fuels causes pollution. Also, if we don’t find new kinds of energy, we will (4) ________ all the fossil fuels in the near future. 1.A. in B. for C. at D. by 2.A. Most B. Mostly C. almost D. Utmost 3.A Because B. Moreover C. Therefore D. However 4.A. use up B. run on C. take over D. cut off TEST 4 I: Choose the correct option A, B, C or D to complete the sentences. 1. This is Linda’s hat, and those shoes are _____________. A. our B. hers C. her D. their 2. It will be ______________ to ride a jet pack in bad weather because it doesn’t have a roof. A. comfortable B. pleasant C. unpleasant D. enjoyable 3. A sky safety system can help cars to ___________ traffic jams and crashes. A. use B. have C. prevent D. take 4. The white cat is Helen’s, and the black cat is ______________. A. I B. my C. mine D. of mine 5. We try to make the future green by using vehicles or kinds of energy that are __________. A. environmentally friendly C. environment friendly B. environmentally friendship D. environmental friendly 6. Skycycling tubes will be easy_____________. A. ride B. to drive C. drive D. to ride 7. I think we ____________ have electric taxis very soon. A. may B. might C. will D. would 8. With teleportation, you disappear at a place, and then _____ in another place seconds later. A. reappear B. reappears C. appears D. appeared 9. Every day over 1,000 new cars add to the city and the city of over 20 million people is getting more and more ___________. A. difficult B. famous C. expensive D. gridlocked 10. My brother and I often come to school _________ foot. A. at B. in C. by D. on 11. With the Segway, the driver pulls the handle to go back or pushed it to go _______. A. fly B. forward C. round D. backward 12. The Segway, which is a __________ vehicle, will be a success. A. two-wheels B. two wheels C. two wheel D. two-wheeled 13. Do you think the ___________ price will increase next month? A. gases B. fossil fuel C. fuel D. natural gases 14. People won’t use flying cars __________ the year 2050. A. after B. before C. during D. until 15. Which _____________ of transport do you think will be used in the future? A. mean B. means C. meanings D. meaning 16. . A jet pack doesn’t __________ a lot of space. A. occur B. bring C. take D. have 17. The city is facing serious ___________ problems. A. pollution B. polluted C. pollute D. pollutant 18. We will use more ___________ energy in the future. A. sun B. sunny C. solar D. sunlight 19. We are looking for types of vehicles that help us to avoid __________. A. walking B. traffic jams C. rush hours D. traffic 20. We believe that urban transport pods can travel ________ around 30kph. A. in B. at C. with D. on

giúp mik vs ạ đag gấp mai nộp òi huhu😢

Giải hộ mình nha cảm ơn nữa nha

Cho tam giác ABC cân tại A, tia phân giác góc A cắt BC tại D. a. Chứng minh DB = DC. b. Kẻ DH AB (H AB), DK AC (K AC). Chứng minh tam giác DHK cân. c. Chứng minh HK // BC.