Exam II Material

Question 1

When someone on earth observes the moon in the first-quarter phase, someone on the moon facing earth observes earth in the:

a) new earth phase
b) first-quarter earth phase
c) crescent earth phase
d) third-quarter earth phase
e) full earth phase

Answer 1

d) third-quarter earth phase

Question 2

Tidal friction caused by earth’s stretching from the moon’s gravity is gradually slowing down the rotation of earth.

T/F

Answer 2

True

Question 3

The moon is slowly moving away from earth.

T/F

Answer 3

True

Question 4

Suppose the sun were suddenly to shrink in size but that its mass remained the same. According to the law of conservation of angular momentum, what would happen?

a) the sun would rotate faster than it does now
b) the sun’s rate of rotation would slow
c) the sun’s angular size in our sky would stay the same
d) this could never happen, because it is impossible for an object to shrink in size without an outside torque

Answer 4

a) the sun would rotate faster than it does now

Question 5

At which lunar phase(s) are tides the most pronounced?

a) both first and third quarters
b) both new and full moons
c) full moon only
d) new moon only
e) third quarter moon only

Answer 5

b) both new and full moons

Question 6

Which of the following best explains why the moon’s orbital period and rotation period are the same?

a) the moon once rotated faster, but tidal friction slowed the rotation period until it matched the orbital period
b) the moon was once closer to earth, but the force of gravity got weaker as the moon moved farther away
c) the law of conservation of angular momentum ensured that the moon must have the same amount of rotational angular momentum as it has of orbital angular momentum
d) the equality of the moon’s orbital and rotational periods is an extraordinary astronomical coincidence

Answer 6

a) the moon once rotated faster, but tidal friction slowed the rotation period until it matched the orbital period

Question 7

Suppose the moon’s orbit were unchanged, but it rotated faster (meaning it did not have synchronous rotation). Which of the following would be true?

a) the moon would go through its cycle of phases in less time than it does now
b) we would no longer always see nearly the same face of the moon
c) tides would be stronger; that is, higher high tides and lower low tides
d) high tides would occur more frequently than they do now
e) all of the above are true

Answer 7

b) we would no longer always see nearly the same face of the moon

Question 8

If the moon is setting at 6A.M., the phase of the moon must be:

a) first quarter
b) third quarter
c) full
d) new
e) waning crescent

Answer 8

c) full

Question 9

Grass (that is healthy) looks green because:

a) it emits green light and absorbs other colors
b) it absorbs green light and emits other colors
c) it transmits green light emits other colors
d) it reflects green light and absorbs other colors

Answer 9

d) it reflects green light and absorbs other colors

Question 10

Everything looks red through a red filter because:

a) the filter emits red light and absorbs other colors
b) the filter absorbs red light and emits other colors
c) the filter transmits red light and absorbs other colors
d) the filter reflects red light and transmits other colors

Answer 10

c) the filter transmits red light and absorbs other colors

Question 11

How are wavelength, frequency, and energy related for photons of light?

a) longer wavelength means lower frequency and lower energy
b) longer wavelength means higher frequency and lower energy
c) longer wavelength means higher frequency and higher energy
d) longer wavelength means lower frequency and higher energy
e) there is no simple relationship because different photons travel at different
speeds

Answer 11

a) longer wavelength means lower frequency and lower energy

Question 12

From lowest energy to highest energy, which of the following correctly orders the different categories of electromagnetic radiation?

a) infrared, visible light, ultraviolet, X rays, gamma rays, radio
b) radio, infrared, visible light, ultraviolet, X rays, gamma rays
c) visible light, infrared, X rays, ultraviolet, gamma rays, radio
d) gamma rays, X rays, visible light, ultraviolet, infrared, radio
e) radio, X rays, visible light, ultraviolet, infrared, gamma rays

Answer 12

b) radio, infrared, visible light, ultraviolet, X rays, gamma rays

Question 13

How much electrical charge does an atom with 6 protons, 6 neutrons, and 5
electrons have?

a) a total charge of +17
b) a negative charge of -5
c) a positive charge of +7
d) a positive charge of +1
e) none of the above

Answer 13

d) a positive charge of +1

Question 14

Consider an atom of gold in which the nucleus contains 79 protons and 118 neutrons. What is its atomic number and atomic weight?

a) the atomic number is 79, and the atomic weight is 197
b) the atomic number is 79, and the atomic weight is 118
c) the atomic number is 118, and the atomic weight is 197
d) the atomic number is 118, and the atomic weight is 79

Answer 14

a) the atomic number is 79, and the atomic weight is 197

Question 15

Consider an atom of gold in which the nucleus contains 79 protons and 118 neutrons. If it is doubly ionized, what is the charge of the gold ion and how many electrons remain in the ion?

a) the gold ion has a charge of +2 and 77 electrons
b) the gold ion has a charge of +2 and 79 electrons
c) the gold ion has a charge of -2 and 77 electrons
d) the gold ion has a charge of +2 and 2 electrons
e) the gold ion has a charge of +79 and no electrons

Answer 15

a) the gold ion has a charge of +2 and 77 electrons

Question 16

Sublimation is the process in which:

a) molecules go from the solid phase to the liquid phase
b) molecules go from the liquid phase to the gas phase
c) molecules go from the solid phase to the gas phase
d) electrons are stripped from atoms
e) electrons are captured by ions

Answer 16

c) molecules go from the solid phase to the gas phase

Question 17

Dissociation is the process in which:

a) the bonds between atoms in a molecule are broken
b) a molecule goes from the solid phase to the gas phase
c) the bonds between electrons around an atomic nucleus are broken
d) an element changes into another form
e) an electron is shared between atomic nuclei

Answer 17

a) the bonds between atoms in a molecule are broken

Question 18

Thermal radiation is defined as:

a) radiation produced by a hot object
b) radiation in the infrared part of the spectrum
c) radiation that depends only on the emitting object’s temperature
d) radiation in the form of emission lines from an object
e) radiation that is felt as heat

Answer 18

c) radiation that depends only on the emitting object’s temperature

Question 19

A perfectly opaque object that absorbs all radiation and reemits the absorbed energy as thermal radiation is:

a) a hot, dense cloud of gas
b) a cold, dense cloud of gas
c) an infrared radiation emitter
d) a thermal emitter
e) transparent

Answer 19

d) a thermal emitter

Question 20

If two objects are the same size but one object is 3 times hotter than the other object, the hotter object emits:

a) 3 times more energy
b) 9 times more energy
c) 12 times more energy
d) 81 times more energy
e) none of the above

Answer 20

d) 81 times more energy

Question 21

If one object has a large redshift and another object has a small redshift, what can we conclude about these two objects?

a) the one with the large redshift is moving toward us faster than the one with the small redshift
b) the one with the large redshift is moving away from us, and the one with the small redshift is moving toward us
c) the one with the large redshift is moving away from us faster than the one with the small redshift
d) the one with the large redshift is hotter and therefore is putting out more radiation
e) the one with the large redshift is redder than the other one

Answer 21

c) the one with the large redshift is moving away from us faster than the one with the small redshift

Question 22

The frequency of a wave is:

a) the number of peaks passing by any point each second
b) measured in cycles per second
c) measured in hertz (Hz)
d) equal to the speed of the wave divided by the wavelength of the wave
e) all of the above

Answer 22

e) all of the above

Question 23

Most stars have spectra showing dark absorption lines against a continuous background of color. This observation indicates that these stars _________.

a) are made almost entirely of hot, low-density gas
b) are made almost entirely of cool, low-density gas
c) have a warm interior that shines through a hotter, high-density gas
d) have a hot interior that shines through a cooler, low-density gas

Answer 23

d) have a hot interior that shines through a cooler, low-density gas

Question 24

When an atom absorbs a photon containing energy, any of the following can happen except which?

a) the atom becomes excited
b) the atom is ionized
c) an electron moves from an upper energy level to a lower one
d) an electron moves from a lower energy level to an upper one

Answer 24

c) an electron moves from an upper energy level to a lower one

Question 25

When an electron in an atom jumps from a high-energy orbital to a lower-energy one, what happens?

a) a photon of light is emitted
b) a photon of light is absorbed
c) the atom’s temperature changes
d) the atoms changes color
e) none of the above

Answer 25

a) a photon of light is emitted

Question 26

An electron-volt is:

a) the charge of one electron
b) the energy of one electron
c) the energy jump between the first and second energy levels of hydrogen
d) an amount of energy much smaller than a joule
e) an amount of energy much larger than a joule

Answer 26

d) an amount of energy much smaller than a joule

Question 27

Compared to red light, blue light has:

a) shorter wavelengths
b) longer wavelengths
c) higher energy photons
d) a and c
e) none of the above

Answer 27

d) a and c

Question 28

What kind of spectrum does a hot gas produce:

a) emission line
b) absorption line
c) continuous
d) infrared
e) ultraviolet

Answer 28

a) emission line

Question 29

The planet Neptune is blue in color. How would you expect the spectrum of visible light from Neptune to be different from the visible-light spectrum of the Sun?

a) the two spectra would have similar shapes, except Neptune’s spectrum would be missing a big chunk of the red light that is present in the Sun’s spectrum
b) the two spectra would have similar shapes, except Neptune’s spectrum would be missing a big chunk of the blue light that is present in the Sun’s spectrum
c) Neptune’s spectrum would peak at a much longer wavelength than the Sun’s spectrum
d) there is no way to predict the answer to this question, since planets and stars are made of such different things

Answer 29

a) the two spectra would have similar shapes, except Neptune’s spectrum would be missing a big chunk of the red light that is present in the Sun’s
spectrum

Question 30

Suppose a photon has a frequency of 300 million hertz (300 megahertz). What is its wavelength?

a) 1 meter
b) 1/300,000 meter
c) 300 million meters
d) a photon’s wavelength cannot be determined from its frequency

Answer 30

a) 1 meter

Question 31

If the moon is setting at noon, the phase of the moon must be:

a) full
b) first quarter
c) third quarter
d) waning crescent
e) waxing crescent

Answer 31

c) third quarter

Question 32

A friend says she saw a planet shining on her meridian at midnight. Which planet can you be sure that she did not see?

a) venus
b) mars
c) jupiter
d) saturn

Answer 32

a) venus