How was Eratosthenes able to determine the approximate circumference of the earth?

Choose one answer.

	a. By measuring the angle the sun made with the vertical at a time when it was known to be directly overhead in a distant city.
	b. By measuring the difference in height of the North Star above the horizon from cities a known distance apart.
	c. By observing a ship entering port and measuring the amount of mast becoming increasingly visible as the ship traveled a known distance toward the port.
	d. By determining the size of the shadow of the earth on the moon during a lunar eclipse.

Question 2

What was the most significant difference in the views of Plato and Aristotle?

Choose one answer.

	a. Plato believed in a geocentric universe while Aristotle believed in a heliocentric universe.
	b. Plato believed the earth was flat while Aristotle believed it was a sphere.
	c. Plato believed that only reason could lead to true knowledge while Aristotle believed that observation and classification could lead to true knowledge.
	d. Plato believed that the material world was the highest form of reality while Aristotle believed in a higher form from which the material world was only an imperfect copy.

Question 3

Which of the following was known by the ancient Greeks?

Choose one answer.

	a. The causes of the phases of the moon.
	b. The causes of eclipses.
	c. The approximate circumference of the earth.
	d. All of the above.

Question 4

Which of the following was NOT part of Aristotle's worldview?

Choose one answer.

	a. Earthly objects were composed of combinations of four basic elements.
	b. Atoms were the basic components of earthly objects.
	c. The earth was spherical in shape.
	d. The laws governing the heavens were different from those governing the earth.

Question 5

Why was the geocentric model of the universe accepted as correct for at least 2,000 years?

Choose one answer.

	a. It just seemed like common sense.
	b. There was no sensation that we lived on an object that was in motion.
	c. The shifting positions of the stars in the sky due to parallax were not observed.
	d. All of the above.

Question 6

8. Which of the following denotes the region of the sky near where the planets can always be found?

Choose one answer.

	a. Celestial equator.
	b. North celestial pole.
	c. Celestial sphere.
	d. Ecliptic.

Question 7

An eclipse of the sun occurs _______.

Choose one answer.

	a. When the moon falls in the shadow of the earth.
	b. When the moon falls in the shadow of the sun.
	c. When the earth falls in the shadow of the moon.
	d. When the earth falls in the shadow of the sun.

Question 8

How long after a new moon will the next third quarter moon appear?

Choose one answer.

	a. About one week.
	b. About two weeks.
	c. About three weeks.
	d. About four weeks.

Question 9

What causes the seasons?

Choose one answer.

	a. The distance from the earth to the sun varies throughout the year.
	b. The axis of rotation of the earth is not perpendicular to the orbit of the earth around the sun.
	c. The energy output of the sun varies throughout the year.
	d. Ocean currents carrying heat to the southern and northern hemispheres alternate throughout the year.

Question 10

What celestial phenomenon is explained by the fact that the plane of the moon's orbit around the earth is not the same as the plane of the earth's orbit around the sun?

Choose one answer.

	a. That solar eclipses only occur during a new moon.
	b. That lunar eclipses only occur during a full moon.
	c. That eclipses do not occur every new or full moon.
	d. Both A and B above.

Question 11

What is it called when the sun crosses the celestial equator in the direction from the northern to the southern celestial hemisphere?

Choose one answer.

	a. Autumnal equinox.
	b. Winter solstice.
	c. Spring equinox.
	d. Summer solstice.

Question 12

Which of the following is true regarding a waxing gibbous moon?

Choose one answer.

	a. It is closer to the sun than the earth is.
	b. It is roughly the same distance from the sun as the earth is.
	c. It is farther from the sun than the earth is.
	d. None of the above. The relative distances from the sun to the earth and waxing gibbous moon vary throughout the year.

Question 13

What was something that the Early Middle Ages had in common with the Greco-Roman era?

Choose one answer.

	a. Both considered knowledge of the material world to be important.
	b. Both believed the universe to be geocentric.
	c. Both were dominated by religious authorities.
	d. Both were times of political stability.

Question 14

Which of the following was NOT a difference between the Early and the Late Middle Ages in the West?

Choose one answer.

	a. The attitude toward science improved in the Late Middle Ages.
	b. Many of the scientific writings of the Greco-Roman era were recovered in the Late Middle Ages.
	c. The rate of literacy increased in the Late Middle Ages.
	d. The model of the universe changed to the heliocentric model in the Late Middle Ages.

Question 15

Which of the following was NOT a contribution to science made by Islamic cultures during the Middle Ages?

Choose one answer.

	a. The use of trigonometry and spherical geometry.
	b. The preservation of ancient Greek and Roman scientific texts.
	c. The replacement of Roman numerals with Arabic numerals.
	d. Advances in optics and the invention of the telescope.

Question 16

How did the Copernican model of the universe account for day and night?

Choose one answer.

	a. By the rotation of the celestial sphere.
	b. By the rotation of the earth.
	c. By the revolution of the sun about the earth.
	d. By the revolution of the earth about the sun.

Question 17

The heliocentric model had completely replaced the geocentric model by the start of the eighteenth century. Why was this so?

Choose one answer.

	a. Kepler's heliocentric model was able to provide calculations that matched the observed orbits of the planets.
	b. Galileo's telescopic observations disproved many features of Ptolemy's geocentric model.
	c. Newton's theory of gravity was compatible with a heliocentric model but not with a geocentric one.
	d. All of the above.

Question 18

Which of the following statements about Copernicus's system of planetary motion is correct?

Choose one answer.

	a. It required epicycles to account for the motion of the planets.
	b. It had planets revolving in elliptical orbits.
	c. It was the first to suggest that the earth revolves around the sun.
	d. It included a force of gravity to keep the planets in their orbits.

Question 19

Which of the following statements best describes the relationship between Kepler's laws of planetary motion and Newton's law of gravity?

Choose one answer.

	a. Kepler's laws are observational facts while Newton's law is a theoretical interpretation.
	b. Kepler's laws are theoretical interpretations while Newton's law is an observational fact.
	c. Both Kepler's laws and Newton's law are theoretical interpretations.
	d. Both Kepler's laws and Newton's law are observational facts.

Question 20

Who is credited with reintroducing the concept of a heliocentric universe in the late fifteenth century?

Choose one answer.

	a. Nicolaus Copernicus
	b. Galileo Galilei
	c. Johannes Kepler
	d. Isaac Newton

Question 21

Who was the first person to develop a mathematical equation to describe gravity?

Choose one answer.

	a. Nicolaus Copernicus
	b. Galileo Galilei
	c. Johannes Kepler
	d. Isaac Newton

Question 22

Who was the first person to use a telescope to determine information about the nature of the universe?

Choose one answer.

	a. Nicolaus Copernicus
	b. Galileo Galilei
	c. Johannes Kepler
	d. Isaac Newton

Question 23

Who was the first person to correctly determine the orbits of the planets?

Choose one answer.

	a. Nicolaus Copernicus
	b. Galileo Galilei
	c. Johannes Kepler
	d. Isaac Newton

Question 24

How does the Bohr model of the atom differ from the planetary model?

Choose one answer.

	a. The Bohr model has most of the mass of the atom in the nucleus.
	b. The electrons are no longer located in the nucleus.
	c. The energy of the atom is quantized.
	d. The electrons no longer orbit the nucleus.

Question 25

What advance in atomic models was made by Ernest Rutherford's model of the atom?

Choose one answer.

	a. It was the first to explain how chemical reactions occur.
	b. It was the first to include electrons as a constituent of the atom.
	c. It was the first to explain atomic spectra.
	d. It was the first to recognize that most of the mass of the atom was concentrated in a tiny nucleus at the center of the atom.

Question 26

What advance in atomic models was made by Niels Bohr?

Choose one answer.

	a. It was the first to explain how chemical reactions occur.
	b. It was the first to include electrons as a constituent of the atom.
	c. It was the first to explain atomic spectra.
	d. It was the first to recognize that most of the mass of the atom was concentrated in a tiny nucleus at the center of the atom.

Question 27

What is the meaning of the Greek word that is the origin of the word atom?

Choose one answer.

	a. Small.
	b. Spherical.
	c. Indivisible.
	d. Matter.

Question 28

Which of the following can be explained using the wave model for light?

Choose one answer.

	a. The bending of light around an obstacle.
	b. The fact that light travels slower in water than it does in air.
	c. Constructive and destructive interference.
	d. All of the above.

Question 29

Which of the following cannot be explained by the particle model for electromagnetic radiation?

Choose one answer.

	a. The photoelectric effect.
	b. The bending of light around an obstacle.
	c. The scattering of X-rays by electrons.
	d. The transition of an atom from a lower energy state to a higher one.

Question 30

Which of the following is a sequence of electromagnetic radiation from longest wavelengths to shortest wavelengths?

Choose one answer.

	a. Infrared, visible, X-ray, ultraviolet, gamma, radio.
	b. Radio, ultraviolet, visible, infrared, X-ray, gamma.
	c. Radio, infrared, visible, ultraviolet, X-ray, gamma.
	d. Radio, infrared, visible, ultraviolet, gamma, X-ray.

Question 31

Which of the following is NOT a region of the electromagnetic spectrum?

Choose one answer.

	a. Radio waves.
	b. Sound waves.
	c. Gamma rays.
	d. Ultraviolet radiation.

Question 32

Which of the following is true for an atom in the ground state?

Choose one answer.

	a. It is in the state with the highest energy.
	b. It can emit but not absorb a photon.
	c. It can absorb but not emit a photon.
	d. It can either emit or absorb a photon.

Question 33

What advance in atomic models was made by J. J. Thompson's plum pudding model?

Choose one answer.

	a. It was the first to explain how chemical reactions occur.
	b. It was the first to include electrons as a constituent of the atom.
	c. It was the first to explain atomic spectra.
	d. It was the first to recognize that most of the mass of the atom was concentrated in a tiny nucleus at the center of the atom.

Question 34

In 1923, how was Hubble able to demonstrate the existence of other galaxies?

Choose one answer.

	a. By applying Newton's law of gravity to stars in nearby spiral nebulae.
	b. By applying Kepler's laws to planets found in nearby spiral nebulae.
	c. By applying the inverse square law to stars of known luminosity in nearby spiral nebulae.
	d. By analyzing the atomic spectra of stars in nearby spiral nebulae.

Question 35

In 1923, how was Hubble able to demonstrate the existence of other galaxies?

Choose one answer.

	a. By measuring the distances to several spiral nebulae.
	b. By showing that the shapes of spiral nebulae were similar to our galaxy.
	c. By measuring the redshifts in the radiation from spiral nebulae.
	d. By measuring the diameters of spiral nebulae and showing that they were about the same size as our galaxy.

Question 36

What best describes the relationship between the expansion of space and Hubble's Law?

Choose one answer.

	a. They are both observational facts.
	b. They are both theoretical interpretations of observational facts.
	c. Hubble's Law is an observational fact and the expansion of space is its theoretical interpretation.
	d. The expansion of space is an observational fact and Hubble's Law is its theoretical interpretation.

Question 37

What differentiates dark matter from ordinary matter?

Choose one answer.

	a. No dark matter has charge.
	b. Dark matter does not emit or absorb electromagnetic radiation.
	c. Dark matter is not a constituent of atoms.
	d. All of the above.

Question 38

What is the correct order of structures in the universe from smallest to largest?

Choose one answer.

	a. Stars, galaxies, voids, clusters, superclusters.
	b. Stars, galaxies, clusters, voids, superclusters.
	c. Stars, voids, galaxies clusters, superclusters.
	d. Stars, galaxies, clusters, superclusters, voids.

Question 39

What is the currently accepted interpretation of the redshifts in the spectra of distant galaxies?

Choose one answer.

	a. That stars in more distant galaxies are younger than those in closer galaxies.
	b. That the distant galaxies are moving away from us through space.
	c. That space is expanding.
	d. That gravity can lengthen the wavelength of light.

Question 40

What two physical quantities does Hubble's Law relate?

Choose one answer.

	a. Recessional velocity and redshift.
	b. Recessional velocity and distance.
	c. Redshift and size.
	d. Recessional velocity and age.

Question 41

Which of the following is a prediction of expanding space?

Choose one answer.

	a. The greater the time light from a distant galaxy spends traveling toward us, the more spread out the wavelengths of the light.
	b. The expansion of space slows down the light from distant galaxies in direct proportion to their distance.
	c. The intensity of light from distant galaxies is reduced in direct proportion to their distance.
	d. The more distant a galaxy is, the farther back in time the light we see left the galaxy.

Question 42

Which of the following structures obey Hubble's Law?

Choose one answer.

	a. Galaxies, clusters, and superclusters, but not stars.
	b. Clusters and superclusters, but not stars or nearby galaxies.
	c. Superclusters, but not stars, nearby galaxies, or clusters.
	d. None of the above. Everything in the universe obeys Hubble's Law.

Question 43

Where is the Solar System located within the Milky Way Galaxy?

Choose one answer.

	a. In the central bulge of the galaxy.
	b. In the halo of the galaxy.
	c. In the disk, about 2/3 of the way from the center of the galaxy.
	d. In the disk, at the edge of the galaxy.

Question 44

What caused scientific opinion to shift suddenly against the steady state model and in favor of the big bang model?

Choose one answer.

	a. The age of the universe was discovered to be finite.
	b. The realization that elements heavier than helium were produced in the interiors of stars.
	c. The interpretation of Hubble's Law that space is expanding.
	d. The discovery of the cosmic background radiation.

Question 45

What is true of Arno Penzias and Robert Wilson with regard to their discovery of the cosmic background radiation?

Choose one answer.

	a. They were aware of Gamow's prediction and set out to discover the radiation.
	b. They were not aware of Gamow's prediction but were aware of Dicke's prediction and set out to discover the radiation.
	c. They were unaware of any prediction and believed that they were the first to make a connection between the radiation and the big bang model.
	d. They were unaware of any prediction and did not realize what they had discovered until later.

Question 46

What was an important difference between the steady state model and the big bang model?

Choose one answer.

	a. The age of the universe.
	b. Whether or not the space was expanding.
	c. The large-scale structure of the universe.
	d. All of the above.

Question 47

What were the two most significant predictions of Gamow's big bang theory?

Choose one answer.

	a. That space was expanding and the existence of the cosmic background radiation.
	b. That space was expanding and that the early universe was nearly pure hydrogen and helium.
	c. That space was expanding and the universe had a finite age.
	d. That the early universe was nearly pure hydrogen and helium and the existence of the cosmic background radiation.

Question 48

Which statement best describes Robert Dicke's role with respect to the cosmic background radiation?

Choose one answer.

	a. He was the first to predict it.
	b. He was not the first to predict it, but he did independently predict it.
	c. He was a member of the team that discovered it.
	d. He was the first to measure its temperature.

Question 49

Who was the first person to introduce a scientific theory in which the universe had a finite age?

Choose one answer.

	a. George Gamow.
	b. Edwin Hubble.
	c. George Lemaitre.
	d. Arno Penzias.

Question 50

What is the primary difference between Gamow's and Lemaitre's theories?

Choose one answer.

	a. Lemaitre's theory concerns the current universe while Gamow's concerns the early universe.
	b. In Lemaitre's theory, the universe was infinitely old, while in Gamow's, it had a finite age.
	c. Gamow's theory made testable predictions while Lemaitre's did not.
	d. In Gamow's theory, the early universe was hot and dense, but in Lemaitre's, it was cool and dense.

Question 51

As the temperature of the early universe decreased due to the expansion of space, structures began to develop. What is the correct order for this formation?

Choose one answer.

	a. Protons and neutrons, atoms, nuclei.
	b. Nuclei, atoms, protons and neutrons.
	c. Protons and neutrons, nuclei, atoms.
	d. Atoms, protons and neutrons, nuclei.

Question 52

What is the cosmic background radiation?

Choose one answer.

	a. Sunlight scattered by dust in the Solar System.
	b. Radioactive material found naturally all over the earth's surface.
	c. Light from the other stars in our galaxy.
	d. A remnant of the early universe.

Question 53

What was the chemical composition of the universe at the time of the formation of the cosmic background radiation?

Choose one answer.

	a. Essentially the same as it is today.
	b. Essentially the same as it is today for the elements lighter than iron, but the very heavy elements had not yet been produced.
	c. Mostly heavier elements because they had not yet had a chance to break down into the lighter elements.
	d. Essentially pure hydrogen and helium.

Question 54

What was the most significant change in the nature of the universe at the time of the formation of the cosmic background radiation?

Choose one answer.

	a. The universe became cool enough for helium nuclei to form.
	b. The temperature of the universe suddenly increased due to the heat of the cosmic background radiation.
	c. Stars and galaxies began to form.
	d. The universe went from an ionized state to a neutral gas.

Question 55

Which of the following is NOT a property of the cosmic background radiation?

Choose one answer.

	a. Its temperature is a few degrees above absolute zero.
	b. It comes from the direction of the center of the universe.
	c. It lies in the radio region of the electromagnetic spectrum.
	d. It forms a continuous spectrum.

Question 56

What determined the sequence of formation of structures in the early universe?

Choose one answer.

	a. The temperature of the universe.
	b. The density of the universe.
	c. The relative strengths of the forces producing the structure.
	d. Both A and C above.

Question 57

Based on WMAP data, what are the components of the present universe in order from the most significant to the least significant?

Choose one answer.

	a. Dark matter, dark energy, atoms.
	b. Dark energy, atoms, dark matter.
	c. Dark energy, dark matter, atoms.
	d. Atoms, dark energy, dark matter.

Question 58

The WMAP probe determined the contents of the universe at the time of the formation of the cosmic background radiation and at the present time. Which of the following is true based on that determination?

Choose one answer.

	a. Dark energy plays a significantly greater role now than it did in the early universe.
	b. Electromagnetic radiation and neutrinos made significant contributions to the content of the early universe, but they are insignificant at the present time.
	c. Both now and in the early universe, dark matter was a more significant component of the universe than ordinary matter.
	d. All of the above.

Question 59

What is the age of the universe determined by the WMAP data?

Choose one answer.

	a. 4.6 billion years.
	b. 10 billion years.
	c. 13.7 billion years.
	d. Approximately 20 billion years.

Question 60

Which of the following is true regarding dark energy?

Choose one answer.

	a. Dark energy produces a universal repulsive force which tends to speed up the expansion of space.
	b. Dark energy is the energy that caused the big bang.
	c. Dark energy is a consequence of dark matter.
	d. All of the above.

Question 61

Which of the following is true regarding gravity and dark energy?

Choose one answer.

	a. In the earlier history, the expansion of space was slowing down because of gravity, but now it is accelerating because of dark energy.
	b. The force of attraction on the universe by gravity has decreased with time, but the force due to dark energy has been constant since the beginning of the universe.
	c. Einstein's theory of gravity, which included the cosmological constant, could explain both gravity and dark energy.
	d. All of the above.

Question 62

Which of the following was NOT a significant discovery of the WMAP probe?

Choose one answer.

	a. The age of the universe.
	b. The contents of the universe at the time of the formation of the cosmic background radiation.
	c. The existence of dark energy.
	d. Strong evidence that the geometry of the universe is flat.

Question 63

Which of the following is a significant difference between gravity and dark energy?

Choose one answer.

	a. Gravity produces a force while dark energy does not.
	b. Gravity has a tendency to slow the expansion of space while dark energy tends to speed it up.
	c. Dark energy caused the initial expansion of space while gravity is working against expansion.
	d. Gravity has been present since the beginning of the universe while dark energy came into existence only after stars and galaxies formed.

Question 64

How is luminosity defined?

Choose one answer.

	a. The energy emitted per unit surface area in the visual region.
	b. The energy emitted per unit area over all wavelengths.
	c. The energy radiated per second over all wavelengths.
	d. The energy radiated over the lifetime of a star.

Question 65

What is the range of luminosities for normal stars?

Choose one answer.

	a. From 100 to 1/100 solar luminosities.
	b. From 1,000 to 1/100 solar luminosities.
	c. From 10,000 to 1/1,000 solar luminosities.
	d. From 1,000,000 to 1/10,000 solar luminosities.

Question 66

What type of star might have a surface temperature of 10,000 K and a luminosity 1/100 times that of the sun?

Choose one answer.

	a. A high-mass main sequence star.
	b. A low-mass main sequence star.
	c. A white dwarf.
	d. A red giant.

Question 67

What type of star might have a surface temperature of 35,000 K and a luminosity of 100,000 times that of the sun?

Choose one answer.

	a. A high-mass main sequence star.
	b. A low-mass main sequence star.
	c. A white dwarf.
	d. A red giant.

Question 68

Where would a very small star with a low luminosity and high surface temperature be located on the Hertzsprung-Russell diagram?

Choose one answer.

	a. Upper left-hand region.
	b. Upper right-hand region.
	c. Lower left-hand region.
	d. Lower right-hand region.

Question 69

Which of the following best describes the core of our sun?

Choose one answer.

	a. A mixture of gas and liquid that, because of its high density, behaves more like a solid.
	b. A very hot gas composed mostly of hydrogen and helium atoms.
	c. A completely ionized state (a plasma) that behaves like a gas.
	d. A mixture of mostly hydrogen and helium that, because of high pressure, behaves like a liquid.

Question 70

Which of the following is true regarding the relationship between the apparent brightness of a star and its luminosity?

Choose one answer.

	a. The more luminous a star the greater its apparent brightness.
	b. The apparent brightness of a star decreases in direct proportion to the distance.
	c. The apparent brightness of a star decreases with the square of the distance.
	d. None of the above. The apparent brightness depends only on the distance of a star and is not related to its luminosity.

Question 71

Which of the following is true regarding the Hertzsprung-Russell diagram?

Choose one answer.

	a. It is a plot of the luminosity of a star versus its surface temperature.
	b. Different regions of the diagram represent different stages in the evolution of a star.
	c. The location of a star on the diagram provides information about the size of the star.
	d. All of the above.

Question 72

As a star exhausts hydrogen in its core, how do the temperature and the luminosity of the central region change?

Choose one answer.

	a. It becomes hotter and more luminous.
	b. It becomes cooler and more luminous.
	c. It becomes hotter and less luminous.
	d. It becomes cooler and less luminous.

Question 73

As a star exhausts hydrogen in its core, how does its surface temperature and luminosity change?

Choose one answer.

	a. It becomes hotter and more luminous.
	b. It becomes cooler and more luminous.
	c. It becomes hotter and less luminous.
	d. It becomes cooler and less luminous.

Question 74

What is (are) the origin(s) of the interstellar medium?

Choose one answer.

	a. The big bang.
	b. Planetary nebula.
	c. Supernovae.
	d. Both A and C.

Question 75

What is the most massive nucleus that can be produced in a high-mass star before it explodes?

Choose one answer.

	a. Carbon.
	b. Silicon.
	c. Iron.
	d. Uranium.

Question 76

What is the primary cause of evolutionary changes in a star?

Choose one answer.

	a. Changes in the chemical composition of the core.
	b. Changes in the density of the core.
	c. Changes in the mass of the star.
	d. Changes in the luminosity of the star.

Question 77

What is the source of the energy radiated by a white dwarf?

Choose one answer.

	a. Nuclear fusion of hydrogen.
	b. Nuclear fusion of heavier elements.
	c. Heat energy left over from its earlier evolution.
	d. A white dwarf is a dead star; it no longer radiates energy.

Question 78

Which of the following is the correct sequence in the death of a high-mass star?

Choose one answer.

	a. Iron core, implosion, neutron core, explosion.
	b. Implosion, iron core, explosion, neutron core.
	c. Neutron core, iron core, implosion, explosion.
	d. Iron core, neutron core, implosion, explosion.

Question 79

Why is energy liberated in the fusion reaction?

Choose one answer.

	a. Because the fusion reactions occur at extremely high temperatures.
	b. Because hydrogen nuclei have the smallest mass of all elements.
	c. Because the helium produced is less massive than the hydrogen that produced it.
	d. Because the helium produced is more massive than the hydrogen that produced it.

Question 80

Your body contains carbon, oxygen, and many other elements heavier than helium. Where were these atoms about 7 billion years ago?

Choose one answer.

	a. In the sun, undergoing fusion.
	b. Part of the planet earth.
	c. Part of a star that is now dead.
	d. Part of the material that had emerged from the big bang.

Question 81

In the hydrogen fusion reaction, what is the net effect on the hydrogen and helium nuclei?

Choose one answer.

	a. The loss of six hydrogen and the gain of two helium.
	b. The loss of six hydrogen and the gain of one helium.
	c. The loss of four hydrogen and the gain of two helium.
	d. The loss of four hydrogen and the gain of one helium.

Question 82

The earth's interior is thought to have melted early in its history. What was the principle cause of the melting?

Choose one answer.

	a. Solar heating.
	b. Continental drift.
	c. Radioactive decay.
	d. The burning of coal and other energy-rich compounds deep in the interior of the earth.

Question 83

The half-life of a particular radioactive material is 12 days. What is the time required for the activity to be reduced to 1/16 of its original value?

Choose one answer.

	a. 24 days.
	b. 36 days.
	c. 48 days.
	d. 60 days.

Question 84

What is our current best theory for the formation of the moon?

Choose one answer.

	a. That it formed by co-accretion at the same time the earth formed.
	b. That it formed by breaking away from the earth because of the very high spin rate of the early earth.
	c. That it formed in a different location in the Solar System and was later gravitationally captured by the early earth.
	d. That it formed by accretion of material eject as a result of a collision between the earth and a massive object.

Question 85

What is our current theory for the formation of the earth?

Choose one answer.

	a. The earth formed from the gravitational collapse of gas and dust.
	b. The earth formed from the accretion of small rock-like bodies.
	c. The earth formed from material that was pulled from the sun by a passing star.
	d. The earth formed from the breakup of a much larger body.

Question 86

What is the current explanation for the origin of the water on the surface of the earth?

Choose one answer.

	a. Outgassing.
	b. Comet bombardment.
	c. Accretion.
	d. Both A and B.

Question 87

What is the principle difference between the present atmosphere of the earth and that of a billion years ago?

Choose one answer.

	a. There is now much more carbon dioxide because of burning coal and gasoline.
	b. Most of the present oxygen has been added by photosynthesis in plants.
	c. Biological activity has removed most of the nitrogen present at that time.
	d. The atmosphere was primarily carbon dioxide at that time but it has since dissolved in the oceans.

Question 88

What were the two major problems faced by the nebular hypothesis for the formation of the Solar System in the early part of the twentieth century.

Choose one answer.

	a. It did not explain the rotation of the planets or the sun.
	b. It did not explain the formation of the planets and the flatness of the Solar System.
	c. It did not explain the rotation of the sun and the formation of the planets.
	d. It did not explain the rotation of the planets and their nearly circular orbits around the sun.

Question 89

Which of the following is NOT a chemical feature of the Solar System explained by the nebular hypothesis?

Choose one answer.

	a. The sun and the Jovian planets have similar compositions.
	b. The terrestrial planets are composed of rocky-metallic materials.
	c. The earth is the only planet with oxygen in its atmosphere.
	d. The satellites of the Jovian planets are rocky-metallic-icy in composition.

Question 90

Which of the following is closest to the age of the Solar System?

Choose one answer.

	a. 50 thousand years.
	b. 5 million years.
	c. 5 billion years.
	d. 14 billion years.

Question 91

The most convincing evidence for evolution comes from which of the following?

Choose one answer.

	a. The similarity between humans and chimpanzees.
	b. The diversity and distribution of species.
	c. The existence of datable fossils.
	d. The fact that virtually all scientists believe in it.

Question 92

What is the hominid species to which Lucy belongs?

Choose one answer.

	a. Australopithecus afaransis.
	b. Australopithecus africanus.
	c. Homo erectus.
	d. Homo habilis.

Question 93

What is the primary structural difference between the australopithecines and Homo erectus?

Choose one answer.

	a. The ability to walk erect.
	b. Cranial capacity.
	c. An opposable thumb.
	d. Differences in the structure of the teeth.

Question 94

Where is the genus Homo believed to have originated?

Choose one answer.

	a. Africa.
	b. The Far East.
	c. The Middle East.
	d. Northern Europe.

Question 95

Which of the following is the correct chronological order from most distant to most recently evolved?

Choose one answer.

	a. Amphibians, primates, fish, reptiles.
	b. Fish, amphibians, reptiles, primates.
	c. Amphibians, fish, reptiles, primates.
	d. Fish, reptiles, amphibians, primates.

Question 96

Which of the following was Homo erectus thought to be the first hominid species to do?

Choose one answer.

	a. Walk on two legs.
	b. Use tools.
	c. Produce works of art.
	d. Migrate out of Africa.

Question 97

Which of the following is true regarding the Miller-Urey experiment?

Choose one answer.

	a. It produced organic compounds such as amino acids.
	b. It produced cell-like structures known as microspheres.
	c. It produced simple living organisms.
	d. It proved that life began in the oceans.

Question 98

What is meant by a star's habitable zone?

Choose one answer.

	a. Its main-sequence lifetime.
	b. The region near its surface where it is cool enough for molecules to exist.
	c. The range of distances from the star between 0.75 and 1.25 AU.
	d. The range of distances from the star where water can exist as a liquid.

Question 99

What is the result of the Drake equation when all the numbers are put in and multiplied?

Choose one answer.

	a. The number of habitable planets in the galaxy at the present time.
	b. The number of planets in the galaxy where life exists at the present time.
	c. The number of planets in the galaxy with technological civilizations at the present time.
	d. The number of planets in the universe with technological civilizations at the present time.

Question 100

Which of the following statements best describes our current state of knowledge regarding the existence of extraterrestrial intelligence?

Choose one answer.

	a. We have shown that we are the only intelligent life in the galaxy.
	b. We have been in radio contact for some time with extraterrestrial civilizations.
	c. It has been established that at least some UFOs represent extraterrestrial contacts.
	d. It is widely accepted that there are billions of earthlike planets in the galaxy, but the existence of other forms of intelligent life is still uncertain.