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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.
The ability to conduct electricity is one of the key properties of a metal. Other solid materials such as silicon can conduct electricity but only effectively at certain temperatures. Also, some substances such as salt (sodium chloride) can conduct when molten or when dissolved in water. The ability of metals to conduct electricity is due to how their atoms bond together. In order to bond together the metal atoms lose at least one of their outermost electrons. This leaves the metal atoms with a positive charge and they are now strictly ions. The lost electrons are free to move in what is known as a sea of electrons. Since the electrons are negatively charged they attract the ions and this is what keeps the structure together.
An electric current is a flow of charge and since the electrons in the sea of electrons are free to move they can be made to flow in one direction when a source of electrical energy such as a battery is connected to the metal. Hence we have an electric current flowing through the wire, and this is what makes metals such good conductors of electricity. The only other common solid conducting material that pencil users are likely to encounter is graphite (what the ‘lead’ of a pencil is made from). Graphite is a form of carbon and again the carbon atoms bond in such a way that there is a sea of electrons that can be made to flow as an electric current. Likewise, if we have an ionic substance like salt we can make the electrically charged ions flow to create a current but only when those ions are free to move, either when the substance is a liquid or dissolved in water. In its solid state an ionic substance like salt cannot conduct electricity as its charged ions cannot flow.
Electrical insulators are substances that cannot conduct electricity well either, because they contain no charged particles or any charged particles they might contain do not flow easily. Water itself is a poor conductor of electricity as it does not contain a significant amount of fully charged particles (the ends of a water molecule are partly charged but overall the molecule is neutral). However, most water we encounter does contain dissolved charged particles, so it will be more conductive than pure water. Many of the problems that occur when touching electrical devices with wet hands result from the ever-present salt that is left on our skin through perspiration and it dissolves in the water to make it more conductive.
Question 46: Electrical conductivity is ______.
A. completely impossible for silicon
B. one of the key properties of most solid materials
C. impossible for any substance when it is dissolved in water
D. one of the most important properties of metals
Question 47: According to the passage, a metal can conduct electricity due to ______.
A. the absence of free electrons
B. the loss of one electron in the core of its atoms
C. the way its atoms bond together
D. its atoms with a positive charge
Question 48: The word “outermost” in paragraph 1 mostly means ______.
A. nearest to the inside B. furthest from the inside
C. the heaviest D. the lightest
Question 49: The atoms of a metal can bond together because ______.
A. electrons can flow in a single direction
B. the lost electrons cannot move freely in the sea of electrons
C. they lose all of their electrons
D. negatively charged electrons attract positive ions
Question 50: Salt in its solid state is not able to conduct electricity because ______.
A. it has free electrons B. its charged ions are not free to move
C. its charged ions can flow easily D. it cannot create any charged ions
Question 51: The word “they” in paragraph 3 refers to ______.
A. electrical insulators B. electric currents
C. charged particles D. charged ions
Question 52: Water is a poor conductor because it contains ______.
A. only a small amount of fully charged particles
B. only a positive electric charge
C. no positive or negative electric charge
D. only a negative electric charge
Question 53: We can have problems when touching electrical devices with wet hands because ______.
A. the water dissolves the salt on our skin and becomes more conductive
B. the water contains too many neutral molecules
C. the water containing no charged particles makes it more conductive
D. the water itself is a good conductor of electricity
Question 54: Which of the following is NOT true according to the passage?
A. Salt can conduct electricity when it is molten or dissolved.
B. Some materials are more conductive than others.
C. Graphite is a common solid substance that can conduct electricity.
D. Pure water is much more conductive than most water we encounter every day.
Question 55: Which of the following could best serve as the title of the passage?
A. Electrical Devices B. Electrical Energy
C. Electrical Insulators D. Electrical Conductivity
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 61 to 70.
A radio telescope is a radio receiver that "sees" radio waves. Unlike a normal telescope, which sees light, a radio telescope is used primarily in the area of astronomy because it can detect radio waves that are emitted by celestial objects. Such objects in space, also called radio objects, can be things such as hot gas, electrons, and wavelengths given off by different atoms and molecules.
The first radio telescope was invented by Grote Reber in 1937. He was an American who graduated with a degree in engineering. He went on to work as an amateur radio operator and later decided to try to build his own radio telescope in his backyard. Reber's first two radio receivers failed to pick up any signals from outer space, but in 1938, his third radio telescope successfully picked up radio waves from space.
A radio telescope consists of a large parabolic-shaped dish antenna or a combination of two or more. The significance of the parabolic shape allows for the incoming radio waves to be concentrated on one focal point, allowing the signals to be picked up as strongly as possible. A larger dish means that more signals can be received and focalized.
In the late 1950s and early 1960s, the largest radio telescope of the time was invented with a seventy-six-meter telescope although larger telescopes have been made since then. The largest current radio telescope in the world is the RATAN-600 in Russia, whose diameter is 576 meters. It has provided valuable feedback of the sun's radio wavelengths and atmosphere. The largest radio telescope in Europe is a 100-meter diameter telescope in Germany, and the largest radio telescope in the United States is the Big Ear in the state of Ohio. The largest array of telescopes is the Giant Metrewave Radio Telescope in India.
Radio telescopes have provided scientists with valuable information about our universe. One of the most important functions of radio telescopes is their ability to allow scientists to track different space probes, the unmanned space missions in outer space. Radio telescopes allow for the travel of space probes into places like the surface of Mars that are too dangerous for men to explore. Without radio wave technology, scientists would not know much of what inhabits the universe nor would they be able to see it. Radio waves are our eyes and ears in outer space.
Question 56: According to the passage, a radio telescope enables the detection of ______.
A. creatures that inhabit celestial objects B. shapes and sizes of celestial objects
C. normal light of celestial objects D. radio waves sent out by celestial objects
Question 57:According to paragraph 2, all of the following are true about Grote Reber EXCEPT that _____.
A. he was an inventor B. he was an amateur radio operator
C. he was an engineer D. he was an astronomer
Question 58: Grote Reber’s idea to develop a radio telescope was not successful until ______.
A. he picked up signals from outer space B. he graduated from an engineering school
C. he experimented on the third one D. he first built one in his backyard
Question 59: The verb “pick up” in paragraph 3 is closest in meaning to ______.
A. send B. lift C. receive D. select
Question 60: According to the passage, which of the following statements is TRUE?
A. A larger dish antenna helps a radio telescope produce better results.
B. The Big Ear in the United States produces the largest array of telescopes.
C. The pattern of radio waves received by radio telescopes is significant.
D. The largest radio telescope of all time is the one with a seventy-six-meter diameter.
Question 61: The word “current” in paragraph 4 is closest in meaning to ______.
A. existing B. moving C. electricity flow D. water movement
Question 62: The word “they” in paragraph 5 refers to ______.
A. places B. radio waves C. scientists D. eyes and ears
Question 63: Radio waves are scientists’ eyes and ears in outer space because ______.
A. they can recognize who dominates the universe
B. they help to track only manned space missions in space
C. they allow them to travel to such dangerous places as Mars
D. they can help them understand more about the universe
Question 64: The focus of discussion in the passage is ______.
A. radio waves B. radio telescopes C. radio operators D. atoms and molecules
Question 65: Originally, this passage was probably published in ______.
A. a business journal B. a fashion magazine
C. a scientific journal D. a book on environment
*Chỉ ra dẫn chứng trong đoạn văn đối với mỗi câu hỏi.
The ability to conduct electricity is one of the key properties of a metal. Other solid materials such as silicon can conduct electricity but only effectively at certain temperatures. Also, some substances such as salt (sodium chloride) can conduct when molten or when dissolved in water. The ability of metals to conduct electricity is due to how their atoms bond together. In order to bond together the metal atoms lose at least one of their outermost electrons. This leaves the metal atoms with a positive charge and they are now strictly ions. The lost electrons are free to move in what is known as a sea of electrons. Since the electrons are negatively charged they attract the ions and this is what keeps the structure together.
An electric current is a flow of charge and since the electrons in the sea of electrons are free to move they can be made to flow in one direction when a source of electrical energy such as a battery is connected to the metal. Hence we have an electric current flowing through the wire, and this is what makes metals such good conductors of electricity. The only other common solid conducting material that pencil users are likely to encounter is graphite (what the ‘lead’ of a pencil is made from). Graphite is a form of carbon and again the carbon atoms bond in such a way that there is a sea of electrons that can be made to flow as an electric current. Likewise, if we have an ionic substance like salt we can make the electrically charged ions flow to create a current but only when those ions are free to move, either when the substance is a liquid or dissolved in water. In its solid state an ionic substance like salt cannot conduct electricity as its charged ions cannot flow.
Electrical insulators are substances that cannot conduct electricity well either, because they contain no charged particles or any charged particles they might contain do not flow easily. Water itself is a poor conductor of electricity as it does not contain a significant amount of fully charged particles (the ends of a water molecule are partly charged but overall the molecule is neutral). However, most water we encounter does contain dissolved charged particles, so it will be more conductive than pure water. Many of the problems that occur when touching electrical devices with wet hands result from the ever-present salt that is left on our skin through perspiration and it dissolves in the water to make it more conductive.
Question 46: Electrical conductivity is ______.
A. completely impossible for silicon
B. one of the key properties of most solid materials
C. impossible for any substance when it is dissolved in water
D. one of the most important properties of metals
Question 47: According to the passage, a metal can conduct electricity due to ______.
A. the absence of free electrons
B. the loss of one electron in the core of its atoms
C. the way its atoms bond together
D. its atoms with a positive charge
Question 48: The word “outermost” in paragraph 1 mostly means ______.
A. nearest to the inside B. furthest from the inside
C. the heaviest D. the lightest
Question 49: The atoms of a metal can bond together because ______.
A. electrons can flow in a single direction
B. the lost electrons cannot move freely in the sea of electrons
C. they lose all of their electrons
D. negatively charged electrons attract positive ions
Question 50: Salt in its solid state is not able to conduct electricity because ______.
A. it has free electrons B. its charged ions are not free to move
C. its charged ions can flow easily D. it cannot create any charged ions
Question 51: The word “they” in paragraph 3 refers to ______.
A. electrical insulators B. electric currents
C. charged particles D. charged ions
Question 52: Water is a poor conductor because it contains ______.
A. only a small amount of fully charged particles
B. only a positive electric charge
C. no positive or negative electric charge
D. only a negative electric charge
Question 53: We can have problems when touching electrical devices with wet hands because ______.
A. the water dissolves the salt on our skin and becomes more conductive
B. the water contains too many neutral molecules
C. the water containing no charged particles makes it more conductive
D. the water itself is a good conductor of electricity
Question 54: Which of the following is NOT true according to the passage?
A. Salt can conduct electricity when it is molten or dissolved.
B. Some materials are more conductive than others.
C. Graphite is a common solid substance that can conduct electricity.
D. Pure water is much more conductive than most water we encounter every day.
Question 55: Which of the following could best serve as the title of the passage?
A. Electrical Devices B. Electrical Energy
C. Electrical Insulators D. Electrical Conductivity
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 61 to 70.
A radio telescope is a radio receiver that "sees" radio waves. Unlike a normal telescope, which sees light, a radio telescope is used primarily in the area of astronomy because it can detect radio waves that are emitted by celestial objects. Such objects in space, also called radio objects, can be things such as hot gas, electrons, and wavelengths given off by different atoms and molecules.
The first radio telescope was invented by Grote Reber in 1937. He was an American who graduated with a degree in engineering. He went on to work as an amateur radio operator and later decided to try to build his own radio telescope in his backyard. Reber's first two radio receivers failed to pick up any signals from outer space, but in 1938, his third radio telescope successfully picked up radio waves from space.
A radio telescope consists of a large parabolic-shaped dish antenna or a combination of two or more. The significance of the parabolic shape allows for the incoming radio waves to be concentrated on one focal point, allowing the signals to be picked up as strongly as possible. A larger dish means that more signals can be received and focalized.
In the late 1950s and early 1960s, the largest radio telescope of the time was invented with a seventy-six-meter telescope although larger telescopes have been made since then. The largest current radio telescope in the world is the RATAN-600 in Russia, whose diameter is 576 meters. It has provided valuable feedback of the sun's radio wavelengths and atmosphere. The largest radio telescope in Europe is a 100-meter diameter telescope in Germany, and the largest radio telescope in the United States is the Big Ear in the state of Ohio. The largest array of telescopes is the Giant Metrewave Radio Telescope in India.
Radio telescopes have provided scientists with valuable information about our universe. One of the most important functions of radio telescopes is their ability to allow scientists to track different space probes, the unmanned space missions in outer space. Radio telescopes allow for the travel of space probes into places like the surface of Mars that are too dangerous for men to explore. Without radio wave technology, scientists would not know much of what inhabits the universe nor would they be able to see it. Radio waves are our eyes and ears in outer space.
Question 56: According to the passage, a radio telescope enables the detection of ______.
A. creatures that inhabit celestial objects B. shapes and sizes of celestial objects
C. normal light of celestial objects D. radio waves sent out by celestial objects
Question 57:According to paragraph 2, all of the following are true about Grote Reber EXCEPT that _____.
A. he was an inventor B. he was an amateur radio operator
C. he was an engineer D. he was an astronomer
Question 58: Grote Reber’s idea to develop a radio telescope was not successful until ______.
A. he picked up signals from outer space B. he graduated from an engineering school
C. he experimented on the third one D. he first built one in his backyard
Question 59: The verb “pick up” in paragraph 3 is closest in meaning to ______.
A. send B. lift C. receive D. select
Question 60: According to the passage, which of the following statements is TRUE?
A. A larger dish antenna helps a radio telescope produce better results.
B. The Big Ear in the United States produces the largest array of telescopes.
C. The pattern of radio waves received by radio telescopes is significant.
D. The largest radio telescope of all time is the one with a seventy-six-meter diameter.
Question 61: The word “current” in paragraph 4 is closest in meaning to ______.
A. existing B. moving C. electricity flow D. water movement
Question 62: The word “they” in paragraph 5 refers to ______.
A. places B. radio waves C. scientists D. eyes and ears
Question 63: Radio waves are scientists’ eyes and ears in outer space because ______.
A. they can recognize who dominates the universe
B. they help to track only manned space missions in space
C. they allow them to travel to such dangerous places as Mars
D. they can help them understand more about the universe
Question 64: The focus of discussion in the passage is ______.
A. radio waves B. radio telescopes C. radio operators D. atoms and molecules
Question 65: Originally, this passage was probably published in ______.
A. a business journal B. a fashion magazine
C. a scientific journal D. a book on environment
*Chỉ ra dẫn chứng trong đoạn văn đối với mỗi câu hỏi.
