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Cho 5 hợp chất hữu cơ A, B, C, D và E là các đồng phân của nhau (chỉ chứa C, H và O), trong đó cacbon chiếm 55,8% và có khối lượng mol phân tử nhỏ hơn 170 g/mol. (a) Xác định công thức phân tử chung của A, B, C, D và E. Trong 5 chất, chỉ có 2 hợp chất A và B cho phản ứng với dung dịch NaHCO3 (có sủi bọt khí), cả A và B đều có nhóm CH3, nhưng hợp chất B có đồng phân cis/trans. Cho từng chất C, D và E phản ứng với dung dịch NaOH, sau đó trung hòa bằng dung dịch HCl, từ C thu được các chất hữu cơ F và G, từ D thu được các chất hữu cơ H và I, từ E thu được các chất hữu cơ K và L. Trong đó G là hợp chất không bền và chuyển hóa ngay thành G’ (G và G’ có cùng công thức phân tử). Cho biết F, H và K cũng cho phản ứng với dung dịch NaHCO3. Khi oxy hóa bằng H2CrO4, hợp chất G’ chuyển hóa thành F và hợp chất L chuyển hóa thành H. Phản ứng của H với bạc nitrat trong amoniac chỉ tạo thành các chất vô cơ. (b) Xác định công thức cấu tạo của các chất và viết các phương trình phản ứng hóa học xảy ra. Cho biết trong các phản ứng trên crôm chuyển hóa thành H2CrO3. (c) Viết phương trình phản ứng polime hóa của A và C. (d) Một trong hai polime thu được trong câu (c) tan dễ trong dung dịch NaOH nguội, polime còn lại không tan trong nước nhưng tan trong dung dịch NaOH nóng. Viết các phương trình phản ứng hóa học xảy ra và giải thích vì sao có sự khác biệt trên.

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Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 36 to 42. The Battle of Gettysburg One of the most important battles of the American Civil War occurred around the small town of Gettysburg, Pennsylvania, from July 1 to July 3, 1863. What began as a search for shoes by the Confederate Army quickly escalated into a major battle. As the Confederate soldiers sought new shoes, they unexpectedly encountered Union cavalry stationed west of the town at Willoughby Run, and the battle began. After much fighting and heavy casualties on both sides, the Confederates pushed the Union forces back through the town of Gettysburg, where they regrouped south of the town along the high ground near a cemetery. Confederate General Robert E. Lee ordered General R.S. Ewell to seize the high ground from the battle - weary Union soldiers "if practical." Ewell hesitated in the attack, giving the Union troops a chance to establish a stronghold along Cemetery Ridge and then bring in reinforcements with artillery. By the time Lee realized Ewell had not attacked, the opportunity had vanished. Other failures by the Confederates included the generals' opposition to the attack plans and a lack of information about Union defense. This combination of errors allowed the Union forces to win a critical victory in the Civil War. By the end, a total of 160,000 men were involved in this fierce and bloody battle. Question 42: Complete the summary by choosing one sentence (A, B, C or D) that is among the most important information to fill in the blank. SUMMARY: This passage discusses the Battle of Gettysburg. The battle began when Confederate and Federal soldiers met by accident near Gettysburg.__________. Failures by the Confederate forces in planning and intelligence allowed the Union army to win the battle.

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  * 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 24 to 30.   Almost all living things ultimately get their energy from the sun. In a process called photosynthesis, plants, algae, and some other organisms capture the sun's energy and use it to make simple sugars such as glucose. Most other organisms use these organic molecules as a source of energy. Organic materials contain a tremendous amount of energy. As food, they fuel our bodies and those of most other creatures. In such forms as oil, gas, and coal, they heat our homes, run our factories and power our cars.   Photosynthesis begins when solar energy is absorbed by chemicals called photosynthetic pigments that are contained within an organism. The most common photosynthetic pigment is chlorophyll. The bright green color characteristic of plants is caused by it. Most algae have additional pigments that may mask the green chlorophyll. Because of these pigments, algae may be not only green but brown, red, blue or even black.                            In a series of enzyme-controlled reactions, the solar energy captured by chlorophyll and other pigments is used to make simple sugars, with carbon dioxide and water as the raw materials. Carbon dioxide is one of very few carbon- containing molecules not considered to be organic compounds. Photosynthesis then converts carbon from an inorganic to an organic form. This is called carbon fixation. In this process, the solar energy that was absorbed by chlorophyll is stored as chemical energy in the form of simple sugars like glucose. The glucose is then used to make other organic compounds. In addition, photosynthesis produces oxygen gas. All the oxygen gas on earth, both in the atmosphere we breathe and in the ocean, was produced by photosynthetic organisms. Photosynthesis constantly replenishes the earth's oxygen supply.   Organisms that are capable of photosynthesis can obtain all the energy they need from sunlight and do not need to eat. They are called autotrophs. Plants are the most familiar autotrophs on land. In the ocean, algae and bacteria are the most important autotrophs. Many organisms cannot produce their own food and must obtain energy by eating organic matter. These are called heterotrophs.   (Hooked on TOEFL Reading - LinguaForum From the passage, we can see that___________.

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Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 36 to 42. The Battle of Gettysburg One of the most important battles of the American Civil War occurred around the small town of Gettysburg, Pennsylvania, from July 1 to July 3, 1863. What began as a search for shoes by the Confederate Army quickly escalated into a major battle. As the Confederate soldiers sought new shoes, they unexpectedly encountered Union cavalry stationed west of the town at Willoughby Run, and the battle began. After much fighting and heavy casualties on both sides, the Confederates pushed the Union forces back through the town of Gettysburg, where they regrouped south of the town along the high ground near a cemetery. Confederate General Robert E. Lee ordered General R.S. Ewell to seize the high ground from the battle - weary Union soldiers "if practical." Ewell hesitated in the attack, giving the Union troops a chance to establish a stronghold along Cemetery Ridge and then bring in reinforcements with artillery. By the time Lee realized Ewell had not attacked, the opportunity had vanished. Other failures by the Confederates included the generals' opposition to the attack plans and a lack of information about Union defense. This combination of errors allowed the Union forces to win a critical victory in the Civil War. By the end, a total of 160,000 men were involved in this fierce and bloody battle. Question 41: The word “they” in paragraph 1 refers to __________.

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Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 36 to 42. The Battle of Gettysburg One of the most important battles of the American Civil War occurred around the small town of Gettysburg, Pennsylvania, from July 1 to July 3, 1863. What began as a search for shoes by the Confederate Army quickly escalated into a major battle. As the Confederate soldiers sought new shoes, they unexpectedly encountered Union cavalry stationed west of the town at Willoughby Run, and the battle began. After much fighting and heavy casualties on both sides, the Confederates pushed the Union forces back through the town of Gettysburg, where they regrouped south of the town along the high ground near a cemetery. Confederate General Robert E. Lee ordered General R.S. Ewell to seize the high ground from the battle - weary Union soldiers "if practical." Ewell hesitated in the attack, giving the Union troops a chance to establish a stronghold along Cemetery Ridge and then bring in reinforcements with artillery. By the time Lee realized Ewell had not attacked, the opportunity had vanished. Other failures by the Confederates included the generals' opposition to the attack plans and a lack of information about Union defense. This combination of errors allowed the Union forces to win a critical victory in the Civil War. By the end, a total of 160,000 men were involved in this fierce and bloody battle. Question 40: The word “escalated” in paragraph 1 could best be replaced by __________.

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Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 36 to 42. The Battle of Gettysburg One of the most important battles of the American Civil War occurred around the small town of Gettysburg, Pennsylvania, from July 1 to July 3, 1863. What began as a search for shoes by the Confederate Army quickly escalated into a major battle. As the Confederate soldiers sought new shoes, they unexpectedly encountered Union cavalry stationed west of the town at Willoughby Run, and the battle began. After much fighting and heavy casualties on both sides, the Confederates pushed the Union forces back through the town of Gettysburg, where they regrouped south of the town along the high ground near a cemetery. Confederate General Robert E. Lee ordered General R.S. Ewell to seize the high ground from the battle - weary Union soldiers "if practical." Ewell hesitated in the attack, giving the Union troops a chance to establish a stronghold along Cemetery Ridge and then bring in reinforcements with artillery. By the time Lee realized Ewell had not attacked, the opportunity had vanished. Other failures by the Confederates included the generals' opposition to the attack plans and a lack of information about Union defense. This combination of errors allowed the Union forces to win a critical victory in the Civil War. By the end, a total of 160,000 men were involved in this fierce and bloody battle. Question 39: According to the passage, which of the following is assumed in the Battle of Gettysburg?

Xem chi tiết 2.9 K lượt xem 6 năm trước

* 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 24 to 30.   Almost all living things ultimately get their energy from the sun. In a process called photosynthesis, plants, algae, and some other organisms capture the sun's energy and use it to make simple sugars such as glucose. Most other organisms use these organic molecules as a source of energy. Organic materials contain a tremendous amount of energy. As food, they fuel our bodies and those of most other creatures. In such forms as oil, gas, and coal, they heat our homes, run our factories and power our cars.   Photosynthesis begins when solar energy is absorbed by chemicals called photosynthetic pigments that are contained within an organism. The most common photosynthetic pigment is chlorophyll. The bright green color characteristic of plants is caused by it. Most algae have additional pigments that may mask the green chlorophyll. Because of these pigments, algae may be not only green but brown, red, blue or even black.                            In a series of enzyme-controlled reactions, the solar energy captured by chlorophyll and other pigments is used to make simple sugars, with carbon dioxide and water as the raw materials. Carbon dioxide is one of very few carbon- containing molecules not considered to be organic compounds. Photosynthesis then converts carbon from an inorganic to an organic form. This is called carbon fixation. In this process, the solar energy that was absorbed by chlorophyll is stored as chemical energy in the form of simple sugars like glucose. The glucose is then used to make other organic compounds. In addition, photosynthesis produces oxygen gas. All the oxygen gas on earth, both in the atmosphere we breathe and in the ocean, was produced by photosynthetic organisms. Photosynthesis constantly replenishes the earth's oxygen supply.   Organisms that are capable of photosynthesis can obtain all the energy they need from sunlight and do not need to eat. They are called autotrophs. Plants are the most familiar autotrophs on land. In the ocean, algae and bacteria are the most important autotrophs. Many organisms cannot produce their own food and must obtain energy by eating organic matter. These are called heterotrophs. (Hooked on TOEFL Reading - LinguaForum Which of the following is NOT true?

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Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 36 to 42. The Battle of Gettysburg One of the most important battles of the American Civil War occurred around the small town of Gettysburg, Pennsylvania, from July 1 to July 3, 1863. What began as a search for shoes by the Confederate Army quickly escalated into a major battle. As the Confederate soldiers sought new shoes, they unexpectedly encountered Union cavalry stationed west of the town at Willoughby Run, and the battle began. After much fighting and heavy casualties on both sides, the Confederates pushed the Union forces back through the town of Gettysburg, where they regrouped south of the town along the high ground near a cemetery. Confederate General Robert E. Lee ordered General R.S. Ewell to seize the high ground from the battle - weary Union soldiers "if practical." Ewell hesitated in the attack, giving the Union troops a chance to establish a stronghold along Cemetery Ridge and then bring in reinforcements with artillery. By the time Lee realized Ewell had not attacked, the opportunity had vanished. Other failures by the Confederates included the generals' opposition to the attack plans and a lack of information about Union defense. This combination of errors allowed the Union forces to win a critical victory in the Civil War. By the end, a total of 160,000 men were involved in this fierce and bloody battle. Question 38: Which of the following best describes how the Battle of Gettysburg began?

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Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 36 to 42. The Battle of Gettysburg One of the most important battles of the American Civil War occurred around the small town of Gettysburg, Pennsylvania, from July 1 to July 3, 1863. What began as a search for shoes by the Confederate Army quickly escalated into a major battle. As the Confederate soldiers sought new shoes, they unexpectedly encountered Union cavalry stationed west of the town at Willoughby Run, and the battle began. After much fighting and heavy casualties on both sides, the Confederates pushed the Union forces back through the town of Gettysburg, where they regrouped south of the town along the high ground near a cemetery. Confederate General Robert E. Lee ordered General R.S. Ewell to seize the high ground from the battle - weary Union soldiers "if practical." Ewell hesitated in the attack, giving the Union troops a chance to establish a stronghold along Cemetery Ridge and then bring in reinforcements with artillery. By the time Lee realized Ewell had not attacked, the opportunity had vanished. Other failures by the Confederates included the generals' opposition to the attack plans and a lack of information about Union defense. This combination of errors allowed the Union forces to win a critical victory in the Civil War. By the end, a total of 160,000 men were involved in this fierce and bloody battle. Question 37: Why does the author mention that "Ewell hesitated to attack"?

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Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 36 to 42. The Battle of Gettysburg One of the most important battles of the American Civil War occurred around the small town of Gettysburg, Pennsylvania, from July 1 to July 3, 1863. What began as a search for shoes by the Confederate Army quickly escalated into a major battle. As the Confederate soldiers sought new shoes, they unexpectedly encountered Union cavalry stationed west of the town at Willoughby Run, and the battle began. After much fighting and heavy casualties on both sides, the Confederates pushed the Union forces back through the town of Gettysburg, where they regrouped south of the town along the high ground near a cemetery. Confederate General Robert E. Lee ordered General R.S. Ewell to seize the high ground from the battle - weary Union soldiers "if practical." Ewell hesitated in the attack, giving the Union troops a chance to establish a stronghold along Cemetery Ridge and then bring in reinforcements with artillery. By the time Lee realized Ewell had not attacked, the opportunity had vanished. Other failures by the Confederates included the generals' opposition to the attack plans and a lack of information about Union defense. This combination of errors allowed the Union forces to win a critical victory in the Civil War. By the end, a total of 160,000 men were involved in this fierce and bloody battle. Question 36: What is the main idea of the passage?

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* 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 24 to 30.   Almost all living things ultimately get their energy from the sun. In a process called photosynthesis, plants, algae, and some other organisms capture the sun's energy and use it to make simple sugars such as glucose. Most other organisms use these organic molecules as a source of energy. Organic materials contain a tremendous amount of energy. As food, they fuel our bodies and those of most other creatures. In such forms as oil, gas, and coal, they heat our homes, run our factories and power our cars.   Photosynthesis begins when solar energy is absorbed by chemicals called photosynthetic pigments that are contained within an organism. The most common photosynthetic pigment is chlorophyll. The bright green color characteristic of plants is caused by it. Most algae have additional pigments that may mask the green chlorophyll. Because of these pigments, algae may be not only green but brown, red, blue or even black.                            In a series of enzyme-controlled reactions, the solar energy captured by chlorophyll and other pigments is used to make simple sugars, with carbon dioxide and water as the raw materials. Carbon dioxide is one of very few carbon- containing molecules not considered to be organic compounds. Photosynthesis then converts carbon from an inorganic to an organic form. This is called carbon fixation. In this process, the solar energy that was absorbed by chlorophyll is stored as chemical energy in the form of simple sugars like glucose. The glucose is then used to make other organic compounds. In addition, photosynthesis produces oxygen gas. All the oxygen gas on earth, both in the atmosphere we breathe and in the ocean, was produced by photosynthetic organisms. Photosynthesis constantly replenishes the earth's oxygen supply.   Organisms that are capable of photosynthesis can obtain all the energy they need from sunlight and do not need to eat. They are called autotrophs. Plants are the most familiar autotrophs on land. In the ocean, algae and bacteria are the most important autotrophs. Many organisms cannot produce their own food and must obtain energy by eating organic matter. These are called heterotrophs.   (Hooked on TOEFL Reading - LinguaForum It can be inferred from the passage that the author considers solar energy to be_________.

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