Amin X chứa vòng benzen và có công thức phân tử C₈H₁₁N. X tác dụng với HCl tạo thành muối dạng R-NH₃Cl. Mặt khác, nếu cho X tác dụng với nước brom thì thu được chất Y có công thức C₈H₁₀NBr_3. Số công thức cấu tạo của X là

A. 2

B. 3

C. 5

D. 6

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions from 38 to 45.

If parents bring up a child with the sole aim of turning the child into a genius, they will cause a disaster. According to several leading educational psychologists, this is one of the biggest mistakes which ambitious parents make. Generally, the child will be only too aware of what his parents expect, and will fail. Unrealistic parental expectations can cause great damage to children

However, if parents are not too unrealistic about what they expect their children to do, but are ambitious in a sensible way, the child may succeed in doing very well – especially if the parents are very supportive of their child.

          Michael Collins is very lucky. He is crazy about music, and his parents help him a lot by taking him to concerts and arranging private piano and violin lessons for him. They even drive him 50 kilometers twice a week for violin lessons. Michael’s mother knows very little about music, but his father plays the trumpet in a large orchestra. However, he never makes Michael enter music competitions if he is unwilling.

          Winston Smith, Michael’s friend, however, is not so lucky. Both his parents are successful musicians, and they set too high a standard for Winston. They want their son to be as successful as they are and so they enter him for every piano competition held. They are very unhappy when he does not win. Winston is always afraid that he will disappoint his parents and now he always seems quiet and unhappy.

Question:All of the following people are musical EXCEPT______.

A. Winston’s father

B. Winston’s mother

C. Michael’s father

D. Michael’s mother

Cho m gam hỗn hợp X gồm 2 ancol no, đơn chức, kế tiếp nhau trong dãy đồng đẳng tác dụng với CuO dư nung nóng, thu được một hỗn hợp chất rắn Z và một hỗn hợp hơi Y ( có tỉ khối so với H₂ là 13,75). Cho toàn bộ Y phản ứng với lượng AgNO₃ dư trong NH₃ đun nóng, thu được 64,8 gam Ag. Giá trị của m là:

A. 9,2.

B. 7,8.

C. 7,4.

D. 8,8.

Thế nào là mức phản ứng của một kiểu gen?