Đốt cháy hoàn toàn 2,9g ankan X thu được 4,49 lít CO2(dktc). Tìm CTPT của X?

Nếu đươc làm cử tri em sẽ chọn những ngừời như thế nào vào làm đại biểu quốc hội hoặc hội đồng nhân dân các cấp

hình chữ nhật có chiều dài 6cm, chiều rộng bằng 3/4 chiều dài . Tính diện tích của hình chữ nhật đó

BÀI TẬP TRẮC NGHIỆM PHÁT ÂM HẬU TỐ ED Choose the word whose underlined part is pronounced differently from the others 1. A. proofs B. books C. points D. pays 2. A. helps B. laughs C. finds D. books 3. A. harbours B. friends C. relatives D. photographs 4. A. packs B. follows C. titles D. writers 5. A. meets B. phones C. books D. makes 6. A. duties B. satellites C. series D. bunnies 7. A. develops B. cakes C. laughs D. volumes 8. A. cyclones B. streets C. books D. makes 9. A. roofs B. regions C. lifts D. rocks 10. A. waves B. houses C. horses D. passes 11. A. remembers B. picks C. walls D. pyramids 12. A. miles B. words C. lists D. names 13. A. sports B. days C. chores D. minds 14. A. nations B. speakers C. cooks D. ends 15. A. seats B. looks C. lends D. stops 16. A. plates B. bags C. photographs D. speaks 17. A. parents B. producers C. weekends D. feelings 18. A. chores B. dishes C. houses D. coaches 19. A. works B. hops C. shifts D. plays 20. A. coughs B. sings C. kits D. sleeps 21. A. signs B. profits C. becomes D. printers 22. A. walks B. steps C. shuts D. papers 23. A. wishes B. practices C. introduces D. leaves 24. A. potatoes B. stretches C. comprises D. grasses 25. A. desks B. maps C. plants D. chairs 26. A. pens B. kicks C. phones D. tables 27. A. houses B. faces C. hates D. places 28. A. smiles B. attends C. drifts D. flows 29. A. trends B. develops C. values D. equals 30. A. repeats B. classmates C. survives D. attacks

Giúp mình bài 2.3 với mn ơii. Please mình cần gấp lắm ạ.

Giúp em với ạ (tiện thể cho em biết công thức tính % của hạt ạ) Nguyên tử B có tổng số hạt là 21. Số hạt không mang điện chiếm 33,33%. Xác định cấu tạo của nguyên tử B. Số hạt không mang điện chiếm 33,33%. Xác định cấu rại của nguyên tử B

a) {-3x + 2. [45 - x - 3 (3x + 7) - 2x ]+4x } = 55 b) 103 - 57 : [-2. (2x - 1$)^{2}$ - (-9$)^{0}$] = -106

Giải hệ phương trình: $\left \{ {{2(x+y)+3(x-y)=4} \atop {(x+y)+2(x-y)=5}} \right.$

chuyển các câu sau sang câu phủ định: 1.He is as tall as I am/me 2.she is as beautiful as her morther is/her mother 3.his close friend is as intelligent as her is/her morther 4.he runs as fast as I run/I do/me 5.she cooks as well as her mother cooks/ her mother does/her mother. 6.he studies english as well as his plays soccer/playing soccer/soccer.

1. Scientists say that exhaust fumes are............. our city. A. poisoning B. poisonous C. poison) 2. Many seabirds were ..........................because of the oil spill. (die/ death/ dead ) 3. Waste from households will gradually ............................. the lake (contaminate/ contamination/ contaminated) 4. Trees can’t grow here because the soil is too ......................... (pollute/ polluted/ pollution) 5. That fierce storm left behind badly......................... buildings. (damage/ damaged/ damaging) 6. What’s a ......................? It’s a substance that contaminates something. (pollute/ polluted/ pollutant) 7. Don’t drink that water. It’s __________. A.damaged B.dumped C.contaminated 8. The team’s success was largely __________ to her efforts. A.because B.due C.since 9. By the time we got to the cinema, the film __________. A.started B.had started C.starting 10. All our English teachers are __________ speakers. A.native B.original C.foreign 11. If you __________ the president, what would you do to help the environment? A.are B .had been C .were 12. Eating too much sugar can __________ to health problems. A.cause B.lead C.make 13. The heavy rain has caused __________ in many parts of the country. A.storms B.floods C.drought 14. The Maori in New Zealand greet each other by _____ their noses. A.punching B.touching C.blowing 15. If the factory ___ dumping poison into the lake, all the fish and other aquatic animals will die. A. continues B. continued C. will continue 16. _______ has made the fish die. A. Waterpollution B. thermal pollution C.noise pollution 17. If the air wasn’tdirty, I ________ so much. A. wouldn’t sneeze B. sneeze C. would sneeze 18 .If you _____ the president, what would you do to help the environment ?A.are B. will be C.were 19. Air___, together with littering, is causing many problems in our cities today. A. pollute B. pollution C. polluting 20. If we __water carefully, more people will have fresh water. A. use B. would use C. using 21. A severe tropical____ is called a typhoon. A. drought B. rain C. storm 22. Noise pollution can lead to________loss. A. looking B. hearing C. listening 23. If I________a millionaire now, I________travel around the world. But in fact, I am very poor and have no money. A. were/ would B. am/ will C. were/ will 24. Emergency teams are still clearing up the ____ from the plane crash. A.debris B.dust C.piece 25............is a sudden, violent shaking og the earth’s surface A. drought B. flood C. earthquake 26. ........ is a long period when there is no rain and not enough water for people, animals and plants A. A. drought B. flood C. earthquake 27. Many people died in the accident. - .................... A. That’s great B. That’s a relief! C. Oh no!