Hòa tan hoàn toàn 13,8g hh gồm Mg và một kim loại hóa trị II bằng đ H2SO4 loãng thu được 26,88l khí (đktc). Kim loại hóa trị II và % khối lượng của nó trong hh là ? A.Be; 65,3% B.Ca; 51% C.Zn;67,2% D.Fe;49,72%

vẽ sơ đồ tổ chức bộ máy thống trị của Pháp khi tiến hành cuộc khai thác thuộc địa lần thứ nhất (1897-1914) ở việt nam.

Cho hình thang ABCD có các cạnh đáy AB = a, CD = b. Qua giao điểm O của hai đường chéo, kẻ đường thẳng song song với AB, cắt AD và BC theo thứ tự ở E và G. Chứng minh 1/OE = 1/OG = 1/a + 1/b. Mn giúp mình viết lời giải chi tiết ra nhé

Tại sao khi trời nồm, đặc biệt ở miền Bắc nước ta, phơi quần áo mãi không khô mà sàn gạch, tường gạch, vách đá lại " đổ mồ hôi "

17 phút 19 giây hay _ 8 phút 25 giây

Cho phương trình x ² - ( 2m-1 )x+m ² -1 = 0 ( x là ẩn số ) a) Tìm điều kiện của m để phương trình đã cho có hai nghiệm phân biệt b) Định m để hai nghiệm x1 , x2 của phương trình đã cho thỏa mãn : ( x1-x2 ) ² = x1 - 3x2

Mọi người giúp em với, em cần gấp lắm ạ II. Rewrite the following sentences without changing the meaning, using the word given 1. Although he is wealthy, he is not spoiled. (despite) ____________________________________________________________________ 2. The view of the mountains is very exciting and impressive. (breathtaking) The view____________________________________________________________ 3. She told me the secret, despite having promised not to do so. (although) ____________________________________________________________________ 4. If you had a wider range of vocabulary, you could write better. (could) Your ____________________ better if you had a wider range of vocabulary. 5. He asked: “How should I deal with school pressure?” (to) He asked me how____________________________________________________ 6. It was 1998.1 met her for the first time. (when) ____________________________________________________________________ 7. He asked me: “What should I do?” (wondered) He_________________________________________________________________ 8. The last time I travelled to Hong Kong was two years ago. (for) I haven’t _____________________________ two years. 9. My parents insist that I study hard. (want) ____________________________________________________________________ 10. The souvenirs here are not expensive. (affordable) The prices of the souvenirs______________________________________________ 11. He asked: “Could you tell me what social skills I should have?” (should) He asked___________________________________________________________ 12. My friend ate a chocolate cake even though she was on a diet. (in spite of) ____________________________________________________________________ 13. Despite a good salary, he was unhappy in his job. (although) ____________________________________________________________________ 14. He said: “Why don’t you call the helpline? They can give you good advice”. (because) He advised me ___________________________ they could give me good advice. 15. In spite of their poverty, they are very generous, (though) ____________________________________________________________________ 16. Though he has been absent frequently, he has managed to pass the test. (in spite of) ____________________________________________________________________ 17. We don’t have to spend too much money to stay at this hotel. (bank) Staying at this hotel___________________________________________________ 18. I have never visited such a historic temple. (historic) This is ________________________________ temple I have ever visited 19. I heard that you had got a new job. I was pleased. (to) I was ___________________________ that you had got a new job. 20. I am stuck in a traffic jam; I want to be somewhere else. (were) I wish I _______________________ in this traffic jam. 21. His passing the exam made me feel much relieved. (that) I was __________________________ he passed the exam 22. Students will be given more opportunities to practise their knowledge. They are active participants. (who) ____________________________________________________________________ 23. My uncle is a fire fighter. He visited us last weekend. (who) ____________________________________________________________________ 24. The storm started at 2 o’clock this morning. It caused a lot of damage. (which) ____________________________________________________________________ 25. It is a camping shop. It has a lot of good equipment. (which) ____________________________________________________________________ 26. A great number of people speak English as a foreign language. Their native language is not English. (whose) ____________________________________________________________________ 27. I have a friend. Her mum is a volunteer worker. (whose) ____________________________________________________________________ 28. The rescue operation was arranged by a charity organisation. It was a success. (which) ____________________________________________________________________ 29. 2015 is the year. My sister became a nurse. (when) ____________________________________________________________________ 30. The Red River Delta is the granary in northern Vietnam. It is formed by the Red River. (which) ____________________________________________________________________

Mình đang cần gấp mà ko có nhiều điểm mong mn giúp mình ạ bn nào giỏi anh thì vào giúp mình với cảm ơn các bn nhiều

Để trung hòa 200ml dung dịch của một axit hữu cơ đơn chức mạch hở cần dùng 300ml dung dịch NaOH 0,5M a/ Tính nồng độ mol/l của dung dịch axit b/ Cô cạn dung dịch đã trung hòa thu được 12,3 g muối khan . Xác định CTPT của axit

Cho tam giác ABC có góc C < 90°. Vẽ BD vuông góc AC (D thuộc AC); CE vuông góc AB (E thuộc AB), BD cắt CE tại H. Biết AB = HC. Tính góc C? Vì đây là một câu hỏi khó với em nên nếu ai trả lời được em sẽ tặng điểm hậu hỉnh ạ! :(