Cho các amin có công thức cấu tạo như sau:

Amin nào có danh pháp gốc – chức là benzylamin? 

A. (3). 

B. (1). 

C. (2). 

D. (4). 

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 4 to 13.

Harvard University, today recognized as part of the top echelon of the world’s universities, came from very inauspicious and humble beginnings. This oldest of America universities was founded in 1636 , just sixteen years after the Pilgrims landed at Plymouth. Included in the Puritan emigrants to the Massachusetts colony during this period were more than 100 graduates of England’s prestigious Oxford and Cambridge universities, and these university graduates in the New World were determined that their sons would have the same educational opportunities that they themselves had had. Because of this support in the colony for an institution of higher learning, the General Court of Massachusetts appropriated 400 pounds for a college in October of 1636 and early the following year decided on a parcel of land for the school; this land was in an area called Newetowne, which was later renamed Cambridge after its English cousin and is the site of the present-day university.

When a young minister named John Harvard, who came from the neighboring town of Charlestowne, died from tuberculosis in 1638, he willed half of his estate of 1,700 pounds to the fledgling college. In spite of the fact that only half of the bequest was actually paid, the General Court named the college after the minister in appreciation for what he had done.The amount of the bequest may not have been large, particularly by today’s standards, but it was more than the General Court had found it necessary to appropriate in order to open the college.

Henry Dunster was appointed the first president of Harvard in 1640, and it should be noted that in addition to serving as president, he was also the entire faculty, with an entering freshman class of four students. Although the staff did expand somewhat, for the first century of its existence the entire teaching staff consisted of the president and three or four tutors.

The underlined word “pounds” are probably……………

A. types of books

B. college student

C. units of money

D. school campuses

Thủy phân hoàn toàn 1 mol oligopeptit X mạch hở thu được 2 mol Gly, 1 mol Ala, 1 mol Val, 1 mol Phe (phenylalanin). Mặt khác, nếu thủy phân không hoàn toàn X thì thu được sản phẩm có chứa Gly- Val và Val-Gly. Số công thức cấu tạo phù hợp của X là

A. 7

B. 5

C. 4.

D. 6.

Đun nóng 0,16 mol hỗn hợp E gồm hai peptit X (C_xH_yO_zN₆) và Y (C_nH_mO₆N_t) cần dùng 600 ml dung dịch NaOH 1,5M chỉ thu được dung dịch chứa a mol muối của glyxin và b mol muối của alanin. Mặt khác, đốt cháy 30,73 gam E trong O₂ vừa đủ thu được hỗn hợp CO₂, H₂O và N₂, trong đó tổng khối lượng của CO₂ và nước là 69,31 gam. Giá trị a : b gần nhất với

A. 0,730

B. 0,810

C. 0,756

D. 0,962

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

Three mile island nuclear power plant

America’s worst accident at a civilian nuclear power plant occurred on March 28, 1979, at Three Mile Island. Operators were trying to repair a problem with piping in the water circulation system, and they accidentally blocked the flow of water. This stopped the removal of heat from the reactor, and began a series of events that would change the way America thought about nuclear power.

Within ten seconds after the flow of water was blocked, the reactor vessel became hotter and the pressure rose. Safety control rods were automatically thrust down into the reactor, causing the chain reaction to stop completely. Pressure, however, continued to build. A relief valve opened but failed to close. As a result, too much water escaped, and the reactor began to melt down.

[1] Large quantities of radioactivity began to leak from the reactor. [2] Most of the radioactivity was contained, and it is likely that no one received a harmful amount of radiation. [3] “Three Mile Island” became the reason that many Americans are afraid of nuclear power to this day. [4]

The word “contained” in the text is closest in meaning to

A. Kept inside

B. Cleaned up

C. Escaped from

D. Kept out

Một lưới thức gồm có 9 loài được mô tả như hình bên. Theo lí thuyết, có bao nhiêu phát biểu sau đây đúng?

I. Có 10 chuỗi thức ăn, trong đó chuỗi dài nhất có 7 mắt xích.

II. Nếu loài K bị tuyệt diệt thì lưới thức ăn này chỉ có tối đa 7 loài.

III. Loài H tham gia vào 10 chuỗi thức ăn.

IV. Chuỗi thức ăn ngắn nhất chỉ có 3 mắt xích.

A. 1

B. 2

C. 4

D. 3