Cho các phát biểu sau:

(a). Phenol tan được trong dung dịch KOH.

(b). Trong các este mạch hở có công thức C₄H₆O₂ có một este được điều chế từ ancol và axit tương ứng.

(c). Có thể phân biệt được chất béo lỏng và hexan bằng dung dịch NaOH, đun nóng.

(d). Có thể chuyển dầu ăn thành mỡ (nhân tạo) bằng phản ứng hiđro hóa.

(e). Tristearin không thể tác dụng với dung dịch axit đun nóng.

(f). Chất béo được dùng làm thức ăn quan trọng của con người.

(g). CH₃COOCH₂C₆H₅ (chứa vòng benzen) có mùi hoa nhài.

Số phát biểu đúng là

A. 4

B. 6

C. 3

D. 5

Khi nói về đặc điểm của mã di truyền, có bao nhiêu phát biểu sau đây đúng?

(1) Mã di truyền được đọc từ một điểm xác định, theo từng bộ ba theo chiều từ 3’ đến 5’ trên mARN.

(2) Mã di truyền có tính phổ biến, tức là tất cả các loài đều có chung một mã di truyền, trừ một vài ngoại lệ.

(3) Mã di truyền có tính thoái hóa, tức là nhiều bộ ba khác nhau cùng xác định một loại axit amin, trừ AUG và UGG.

(4) Mã di truyền có tính đặc hiệu, tứ là một bộ ba chỉ mã hóa cho một loại axit amin.

A. 3.

B. 1.

C. 2.

D. 4.

Trộn bột Al với m gam hỗn hợp X gồm CuO, Fe₃O₄, MgO, Cr₂O₃ rồi nung nóng thu được 240 gam hỗn hợp Y. Để hòa tan hoàn toàn Y thì phải dùng hết 450 ml dung dịch NaOH loãng 2M. Mặt khác, lấy ½ hỗn hợp Y cho tác dụng với dung dịch HNO₃ thì thu được 12,32 lít khí NO (spk duy nhất). Thành phần phần trăm về khối lượng của Fe₃O₄ trong hỗn hợp X là:

A. 58,00%

B. 64,53%

C. 48,33%

D. 53,17%

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 35 to 42.

  Plants and animals will find it difficult to escape from or adjust to the effects of global wanning. Scientists have already observed shifts in the lifecycles of many plants and animals, such as flowers blooming earlier and birds hatching earlier in the spring. Many species have begun shifting where they live or their annual migration patterns due to warmer temperatures.

  With further warming, animals will tend to migrate towards the poles and up mountainsides towards higher elevations. Plants will also attempt to shift their ranges, seeking new areas as old habitats grow too warm. In many places, however, human development will prevent these shifts. Species that find cities or farmland blocking their way north or south may become extinct. Species living in unique ecosystems, such as those found in polar and mountaintop regions, are especially at risk because migration to new habitats is not possible. For example, polar bears and marine mammals in the Arctic are already threatened by dwindling sea ice but have nowhere farther north to go.

  Projecting species extinction due to global warming is extremely difficult. Some scientists have estimated that 20 to 50 percent of species could be committed to extinction with 2 to 3 Celsius degrees of further warming. The rate of warming, not just the magnitude, is extremely important for plants and animals. Some species and even entire ecosystems, such as certain types of forest, may not be able to adjust quickly enough and may disappear.

  Ocean ecosystems, especially fragile ones like coral reefs, will also be affected by global warming. Warmer ocean temperatures can cause coral to “bleach”, a state which if prolonged will lead to the death of the coral. Scientists estimate that even 1 Celsius degree of additional warming could lead to widespread bleaching and death of coral reefs around the world. Also, increasing carbon dioxide in the atmosphere enters the ocean and increases the acidity of ocean waters. This acidification further stresses ocean ecosystems.

(From "Global Warming" by Michael Mastrandrea and Stephen H, Schneider)

According to the passage, if some species are not able to adjust quickly to warmer temperatures, _____________ .

A. they may be endangered

B. they can begin to develop.

C. they will certainly need water

D. they move to tropical forests.

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 28 to 34.

  Music therapy is using music to help people with a variety of problems. For example, it can help people with communication and speech problems speak better. It can help people with memory problems remember things from their past. Music therapy can also help people manage stress and be more relaxed. It can even make people with bad pain feel better.

  In music therapy, a music therapist works with one person alone or with small groups. The therapist meets with the person and does tests to find out what the problem is and what the person can do with music. Then the therapist decides what kind of music therapy to use. Some people sing, and others might compose music, but a person doesn’t need to know about music to be helped by music therapy. There are options such as listening to music and dancing to music. Research shows that these activities are good for the body and for the mind.

  Homes that take care of elderly people often have music therapy programs. The programs help the elderly be more energetic and also help with memory problems. Some hospitals have music therapy for patients who are in a lot of pain. Music can affect a part of the brain that reduces pain.

  Trevor Gibbons is one example of a person who was helped by music therapy. In 2000, he was putting in windows on the fourth floor of a building when he fell. He was in the hospital for over a year. He was in a lot of pain, and he couldn’t talk. He went from the hospital to a rehabilitation center that has a music therapy program, and a music therapist worked with him for several years. He could sing more easily than he could talk. Trevor says that music also helped him manage loneliness, sadness, and pain after he was hurt. Music and the music therapist inspired him, and he has written and sung many songs. He has even recorded CDs and performed at Lincoln Center in New York.

(From “Four Corners 4" by Jack C. Richards and David Bohlke)

Which of the following statements is TRUE about music therapy?

A. Trevor Gibbons was not helped by music therapy.

B. A music therapist always works with one person each time.

C. A person must know about music to be helped by music therapy.

D. Music can reduce pain by affecting a part of the brain.