Gọi -e là điện tích của mỗi electron. Biết nguyên tử ôxi có 8 electron bay xung quanh hạt nhân. Hỏi điện tích hạt nhân của nguyên tử ôxi là bao nhiêu? Vì sao em biết điều đó.

- viết một bài văn nghị luận về vấn đề tai nạn giao thông

Cho dãy số (Un)vs Un=(n-1)√2n+2/n^4+n^2-1.tính limUn

EXERCISE 4: Choose the correct sentence among A, B, C or D which has the same meaning as the given one. 1. Eight years ago we started writing to each other. A. We have rarely written to each other for eight years. B. Eight years is a long time for us to write to each other. C. We wrote to each other eight years ago. D. We have been writing to each other for eight years. 2. The boy was so lazy that he couldn’t stay up late to learn his lessons. A. The boy was lazy enough not to stay up late to learn his lessons. B. The boy was too lazy to stay up late to learn his lessons. C. The boy was lazy enough but he stayed up late to learn his lessons. D. The boy was lazy enough to stay up late to learn his lessons. 3. My father is tired of seeing any violent films. A. My father hasn’t seen a violent film. B. My father has enjoyed all the violent films he has ever seen. C. My father is worried about missing the next violent film.D. My father never wants to see another violent film. 4. As soon as he waved his hand, she turned away. A. He saw her turn away and he waved his hand. B. No sooner had he waved his hand than she turned away. C. She turned away because he waved his hand too early. D. Although she turned away, he waved his hand. 5. John wishes he had remembered to send Mary a Christmas card. A. John regrets not to send Mary a Christmas card. B. John regrets forgetting not to send Mary a Christmas card. C. John regrets not remembering sending Mary a Christmas card. D. John regrets forgetting to send Mary a Christmas card. 6. My father hasn’t smoked cigarettes for a month. A. It’s a month since my father last smoked cigarettes. B. It’s a month ago that my father smoked cigarettes. C. It’s a month that my father hasn’t smoked cigarettes. D. It’s a cigarette that my father smoked a month ago. 7. Having finished their work, the workers expected to be paid. A. The workers expected to be paid because they had finished their work. B. Having their work finishing, the workers expected to be paid. C. Having expected to be paid, the workers finished their work. D. Having been finished their work, the workers expected to be paid. 8. Mr. Brown bought this car five years ago. A. Mr. Brown started to buy this car for five years. B. It has been five years when Mr. Brown has bought this car. C. Mr. Brown has had this car for five years . D. It is five years ago since Mr. Brown has bought this car. 9. John used to write home once a week when he was abroad. A. John doesn’t write home once a week any longer. B. John enjoyed being written home every week when he was abroad. C. John never forgot to write a weekly letter home when he was abroad. D. When he was abroad he remembered to write home every week. 10. I haven’t enjoyed myself so much for years. A. It’s years since I enjoyed myself so much. B. It’s years since I have enjoyed myself so much. C. It was years since I had enjoyed myself so much. D. It has been years since I have enjoyed myself so much.

Giúp em 3 câu này với ạ , em cảm ơn 🥰

1. Mai wants some apples. Mai'd _________________ 2. He feels hot and thirsty.-He _____________ 3. He would like to read books.-He______________ 4. He likes fish.-His favorite______________________

Bài 2 tìm x a) 4(3x-4)-2=18 b) B= { x ∈ N /30< x ≤ 40 c)(150 – x ) : 25 = 30 +1 d) 2x-138=22x 32 e)(6x-39).28=5628 f) (9x+3)x2=60 e)26-3x:5+71 =75 h)5x+1=125 Mong Mọi người giúp mink ạ !! ai nhanh vs đúng mink vote 5 sao + cảm ơn + tăng điểm + lựa chọn câu trả lời hay nhất !!!! cần gấp lắm chiều 2h là nộp : ⊂ ⊕ ⊕ ⊕ ⊕ ⊕ ⊕ ⊕

Câu 1: Đốt cháy hoàn toàn 4,48 lít hai anken đồng đẳng kết tiếp của nhau (đktc) thu được 11,2 lít CO2 (đktc). Tìm CTPT của 2 anken đó. Câu 4: (3,0 điểm): Dẫn 4,48 lít hỗn hợp 3 khí etan, etilen, axetilen qua dung dịch brom (dư) thì thấy có 1,12 lít khí thoát ra ngoài. Cũng dẫn 4,48 lít khí trên qua dung dịch AgNO3/NH3 thì thấy có 21,6g kết tủa ( các khí đo ở đktc). a. Viết phương trình phản ứng xảy ra. b. Xác định phần trăm về thể tích của mỗi khí trong hỗn hợp đầu (Ag =108)

Trình bày nội dung Hiệp ước Hac- mang 1862 và Hiệp ước Patonot 1884?

1. Choose the word whose underlined part is pronounced differently from that of the others in each group. A. knight B. night C. five D. skip 2. Choose the word whose main stressed syllable is placed differently from that of the others in each group. A. design B. postcard C. impose D. discover II. VOCABULARY AND GRAMMAR Choose the words ( from A, B, C or D ) to complete the sentences. 3. Have you ever .................. aerobics? Aerobic exercise can help you to lose weight. A. played B. done C. gone D. got 4. Angkor in Cambodia has been listed as a UNESCO World.................................... A. Wonder B. Common C. Country D. Heritage 5. I really love living in Montreal ......... there are so many places to visit that are nearby. A. but B. so C. because D. although 6. The red double-decker bus is London's famous.................................................. A. sign B. signal C. symbol D. logo 7. I have never seen such a strange ............................ It has green color and big eyes. A. palace B. continent C. creature D. time 8. When we were in Stockholm, we had coffee and cakes ...................... a coffee shop ...................the Old Town. A. on - on B. at - at C. in - in D. on - at 9. Gustave Eiffel was well-known for ............................................... Eiffel tower. A. design B. designing C. to design D. designed 10. London is one of the most interesting city I ...................................... .................. A. ever visit B. have ever visited C. ever visited D. will ever visit