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Contemporary's GED Science
Robert Mitchell

History and Nature of Science

GED Practice Quiz


Choose the one best answer to each question. When you have finished the quiz, click on Submit Answers to receive feedback and results. You may also choose to e-mail your results to your instructor.


The first recorded description of an atom occurred more than 2,000 years ago. The Greek philosopher Democritus imagined that all matter and substances were made of atoms. Democritus gave his basic particle the name atom, which means "uncuttable." Democritus described atoms as small, hard particles, all composed of the same substance but of different sizes and shapes.

For more than 1700 years, Democritus’ ideas went unchallenged. Then, in 1750, Rudjer Boscovich suggested that Democritus might have been wrong. Boscovich believed that atoms were cuttable or divisible and that atoms contain smaller parts that could, in turn, be divided into still smaller parts, until the fundamental building blocks of matter were reached. Today, most atomic physicists accept a modern form of this idea.

How are Democritus’ and Boscovich’s ideas alike?
Need a Hint?
A)They each involve substances.
B)They each assume that an atom cannot be divided into smaller particles or parts.
C)They each indicate that substances are made of different types of small particles.
D)They each give the same description for the structure of an atom.
E)The ideas of Democritus and Boscovich have nothing in common.

Questions 2 and 3 refer to the following information and diagrams.

In 1803 John Dalton suggested that each element is made of only one kind of atom. Dalton said that the elements were different because their basic atoms are different, but all atoms of a specific element are identical. By the end of the century, in 1897, Joseph John Thomson proved that the atom was "cuttable." That is, he proved that there were particles smaller than atoms that were part of atoms. Thomson had discovered electrons. Thomson proposed a model of the atom in which negatively charged electrons were distributed throughout a positively charged sphere, a bit like blueberries spread throughout a muffin. Thomson’s model intrigued the scientific community, and other scientists set out to investigate the structure of the atom.

Just over twenty years later, in 1911, Ernest Rutherford, a former student of Thomson’s, presented a different theory of the structure of atoms. Rutherford’s experimental work led him to conclude that nearly all the mass of an atom is concentrated in a tiny nucleus. He also stated that the nucleus is surrounded by electrons traveling at tremendous speeds through the atom’s outer regions. It was as if the nucleus was at the center of a cloud of electrons. Because the atom had no overall electrical charge, Rutherford concluded that the nucleus of an atom had a positive charge.

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How did Dalton explain why one element is different from another?
Need a Hint?
A)There were particles smaller than atoms that were a part of atoms.
B)Each had a tiny nucleus.
C)Their basic atoms were different.
D)Their electrons were different.
E)Electrons were spread throughout an atom.

What was the greatest difference between Thomson’s model and Rutherford’s model?
Need a Hint?
A)Thomson’s model had larger electrons.
B)Thomson’s had smaller electrons.
C)Rutherford’s model had a central nucleus that carried a positive charge.
D)Rutherford’s model atom had electrons spread throughout the atom.
E)Rutherford’s atom had electrons at the center of an atom.

Questions 4 and 5 refer to the following information and diagrams.

In 1913 Niels Bohr, who had worked with Rutherford, suggested that negatively charged electrons could travel in a certain set of orbits around the nucleus, like planets orbiting around the sun. Each orbit was associated with a specific level of energy. The electrons in larger orbits, that is, farther away from the nucleus, had higher energies.

By 1928 another description of electron arrangement was proposed. The work of Erwin Schrodinger, Wolfgang Pauli, Max Born, and Werner Heisenberg led to the assumption that the electron, although a particle, could behave like a wave. This led to the development of the electron cloud model. As in the Rutherford atom, the nucleus is at the center of an atom. But this model proposes that the nucleus is surrounded by electrons moving in paths like a wavy band of clouds around the nucleus. Each path is associated with a particular level of electron energy.

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Which of these is a hypothesis that can be drawn from either the Bohr or the electron cloud model of an atom?
Need a Hint?
A)If an atom has a nucleus, then it must have electrons.
B)Electrons need a certain amount of energy to overcome the attraction of a positive nucleus.
C)Electrons have a positive charge.
D)An atom is neutral, so some electrons must have a negative charge, and some must have a positive charge.
E)The nucleus moves around an atom in circles, or shells, each with a particular level of energy.

Which of the following is NOT supported by the passage and diagram?
Need a Hint?
A)The nucleus of an atom orbits around the atom’s electrons.
B)Both the Bohr atom and the electron cloud model have a central nucleus.
C)The electron cloud model of an atom has characteristics that were part of earlier atomic models.
D)In both models, electrons have specific energy levels.
E)Both atomic models are based on how atoms and electrons behave and react.

Questions 6 through 10 refer to the following information.

1897J. J. Thomson discovers the electron—a small negative particle in an atom—while investigating the rays that occur as electricity passes through a vacuum in a glass tube.As some researchers and scientists worked to discover just what particles or parts an atom has, other researchers began to investigate the behavior of the particles they did know about. For instance, after J. J. Thomson identified the electron as a part of an atom, others investigated the properties and behavior of electrons. This work led to inventions that affected radio reception, long-distance telephone calls, and eventually television and computers.

In 1914 AT&T, the country’s only telephone company, began to string a series of triodes across the nation so that people could make coast-to-coast telephone calls. Even though the scheme worked, the vacuum tubes were not efficient. The tubes broke easily. They were large and required a lot of space. Most of all, they generated a tremendous amount of heat—an indication that they were wasting energy.

Many people at the telephone company recognized that something better was needed. There was a new class of materials being investigated. These materials were not quite insulators and not quite conductors—they were called semiconductors. Perhaps they were the key.

To that end, Bell Labs put together a team of scientists—William Shockley, John Bardeen, and Walter Brattain—to develop a semiconductor device to replace the vacuum tube. In the spring of 1945, Shockley produced the first design but it failed. He directed Bardeen and Brattain to find out why. Bardeen and Brattain divided the workload. Bardeen would suggest experiments and interpret results; Brattain would build and execute the experiments.

In winter 1947 Bardeen discovered that their ideas of how electrons behaved in semiconductors was wrong! He and Brattain followed a new course, and together they built a point-contact transistor that successfully amplified signals. When Bardeen and Brattain told Shockley of their success, Shockley was glad the team had succeeded but unhappy that Bardeen and Brattain had devised the transistor without his participation. Shockley decided he would have to build a better device on his own, breaking apart a once cooperative team.

By the beginning of 1948, Shockley had worked out how the new and improved transistor might work. It took two years to actually build it. Shockley’s sandwich transistor was sturdier and more useful than the device his colleagues had built. What’s more, Shockley’s transistor would prove easier to manufacture.
1904John Fleming developed the diode, a vacuum tube that could detect radio signals.
1907Lee De Forest patented a triode, an improved vacuum tube.
1909AT&T announces its intention to provide nationwide telephone service by developing a coast-to-coast (3,400 mile) phone system.
1910Edwin Howard Armstrong, uses a triode to strengthen, or amplify, radio signals. Triodes become key in radio broadcasting and reception.
1912De Forest's triode used as an amplifier for long-distance telephone calls.
1914AT&T uses De Forest's triodes to make coast-to-coast telephone calls possible.
Vacuum tubes, such as the diode and triode, made possible such electronic inventions as television, radar, and computers.
1920s Researchers begin studying the properties of semiconductor materials.
1923De Forest introduces first sound-on-film motion picture.
1926AT&T establishes Bell Laboratories where scientists are encouraged to pursue basic research. The company plans to put any significant discoveries to good use.
1945John Bardeen, and Walter Brattain, and William Shockley begin work together at Bell Labs.
1946ENIAC, first digital computer built using 18,000 vacuum tubes. The computer takes up an entire room.
1947John Bardeen and Walter Brattain build the first point-contact transistor. It is the first working solid-state amplifier.
1951William Shockley devises the first sandwich, or junction, transistor, a more rugged and dependable amplifier.


What basic part of the atom proved useful in radio broadcasting?
Need a Hint?
E)silicon chips

What was the relationship of Armstrong’s work to the work of De Forest?
Need a Hint?
B)Armstrong used De Forest’s triode to strengthen radio signals.
C)De Forest used Armstrong’s discovery to build a triode.
D)De Forest and AT&T use diodes to amplify coast-to-coast telephone calls.
E)Armstrong improved the diode.

Which of the following statements is supported by the passage and the timeline?
Need a Hint?
A)Everything useful in science has been discovered by a single scientist.
B)Semiconducting elements were developed for the telephone company.
C)Vacuum tubes that made nationwide phone calls possible were also useful in televisions and computers.
D)The work of Shockley, Bardeen and Brattain in the 1940s had nothing to do with the work of Thomson in the 1890s.
E)The work of Shockley in the late 1940s had nothing to do with the work of Bardeen and Brattain in 1947.

Which of the following lists items in chronological order of their study, discovery, or design?
Need a Hint?
A)electrons, triodes, semiconductors, transistors, diode
B)electrons, diodes, semiconductors, transistors, triodes
C)semiconductors, diodes, triodes, electrons, transistors
D)electrons, transistors, diodes, triodes, semiconductors
E)electrons, diodes, triodes, semiconductors, transistors

Which of the following is an opinion?
Need a Hint?
A)The shortcomings of vacuum tubes were responsible for the development of transistors.
B)Solid-state diodes are cheaper and easier to make than vacuum tube diodes.
C)The transistor was probably the most important invention of the past 50 years.
D)Teams of scientists often work together to solve problems.
E)Companies as well as individuals can be important to scientific research.