Công thức tính tổng trở đoạn mạch gồm điện trở thuần R, cuộn dây thuần cảm có cảm kháng ZL và tụ điện có dung kháng ZC mắc nối tiếp là:

Nghiên cứu một dung dịch chứa chất tan X trong lọ không dán nhãn và thu được kết quả sau: X đều có phản ứng với cả 3 dung dịch : NaHSO4, Na2CO3 và AgNO3. X không phản ứng với cả 3 dung dịch : NaOH, Ba(NO3)2, HNO3. Vậy dung dịch X là dung dịch nào sau đây?         

Read the following passage and choose the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks:

Why is it that many teenagers have the energy to play computer games until late at night but can’t find the energy to get out of bed (26) __________ for school? According to a new report, today’s generation of children are in danger of getting so (27)________ sleep that they are putting their mental and physical health at (28)_________. Adults can easily survive on seven to eight hours sleep a night, (29)____________teenagers require nine or ten hours. According to medical experts, one in five youngsters (30)___________ anything between two and five hours sleep a night less than their parents did at their age.

Question 27:

Cho 26,9 gam hỗn hợp gồm Mg, Zn và Fe vào 400ml dung dịch Cu(NO3)2 0,75M và AgNO3 1,25M. Kết thúc phản ứng thu được dung dịch X và chất rắn Y gồm 2 kim loại. Cho NaOH dư vào dung dịch X, lọc lấy kết tủa nung ngoài không khí đến khối lượng không đổi thu 30,0 gam hỗn hợp gồm 2 oxit. Phần trăm số mol của Zn trong hỗn hợp ban đầu là.         

Read the following passage and choose the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks:

Why is it that many teenagers have the energy to play computer games until late at night but can’t find the energy to get out of bed (26) __________ for school? According to a new report, today’s generation of children are in danger of getting so (27)________ sleep that they are putting their mental and physical health at (28)_________. Adults can easily survive on seven to eight hours sleep a night, (29)____________teenagers require nine or ten hours. According to medical experts, one in five youngsters (30)___________ anything between two and five hours sleep a night less than their parents did at their age.

Question 26:

Cho hỗn hợp X gồm 0,12 mol CuO; 0,1 mol Mg và 0,05 mol Al2O3 tan hoàn toàn trong dung dịch chứa đồng thời 0,15 mol H2SO4 (loãng) và 0,55 mol HCl, thu được dung dịch Y và khí H2. Nhỏ từ từ dung dịch hỗn hợp Ba(OH)2 0,1M và NaOH 0,6M vào Y đến khi thu được khối lượng kết tủa lớn nhất, lọc kết tủa đem nung đến khối lượng không đổi, thu được m gam chất rắn khan. Giá trị của m gần nhất với giá trị nào sau đây?         

Read the following passage and choose the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks:

Why is it that many teenagers have the energy to play computer games until late at night but can’t find the energy to get out of bed (26) __________ for school? According to a new report, today’s generation of children are in danger of getting so (27)________ sleep that they are putting their mental and physical health at (28)_________. Adults can easily survive on seven to eight hours sleep a night, (29)____________teenagers require nine or ten hours. According to medical experts, one in five youngsters (30)___________ anything between two and five hours sleep a night less than their parents did at their age.

Question 29:

Cho dãy các kim loại: Fe, Cu, Mg, Ag, Al, Na, Ba. Số kim loại trong dãy phản ứng được với dung dịch HCl là  

Read the following passage and choose the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks:

Why is it that many teenagers have the energy to play computer games until late at night but can’t find the energy to get out of bed (26) __________ for school? According to a new report, today’s generation of children are in danger of getting so (27)________ sleep that they are putting their mental and physical health at (28)_________. Adults can easily survive on seven to eight hours sleep a night, (29)____________teenagers require nine or ten hours. According to medical experts, one in five youngsters (30)___________ anything between two and five hours sleep a night less than their parents did at their age.

Question 28:

Kim loại nào sau đây không phản ứng với dung dịch CuSO4?         

Read the following passage and choose the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks:

Why is it that many teenagers have the energy to play computer games until late at night but can’t find the energy to get out of bed (26) __________ for school? According to a new report, today’s generation of children are in danger of getting so (27)________ sleep that they are putting their mental and physical health at (28)_________. Adults can easily survive on seven to eight hours sleep a night, (29)____________teenagers require nine or ten hours. According to medical experts, one in five youngsters (30)___________ anything between two and five hours sleep a night less than their parents did at their age.

Question 30:  

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