Astronomy Chapter 4

True or False A low density gas must be hot in order to produce an absorption line.

False

True or False All wavelengths of light travel at the same speed in a vacuum, and carry the same energy per photon.

False

True or False Molecular spectra, like elemental ones, involve only the vibration of the particles.

False

True or False The radial velocity of a star's motion in space can also broaden its spectral lines.

False

True or False The red hydrogen alpha line carries more energy per photon than the blue-green hydrogen beta line does.

False

If a hydrogen atom encounters a photon of energy, what will its electron do? a. Absorb the photon only if it has the exact energy needed to move to another energy level b. Ignore the photon so it can remain in the ground state, the state of lowest energy c. Absorb only as much of the photon's energy as it needs to move to the next energy level d. Absorb the photon and jump to whatever position corresponds to its new energy

a. Absorb the photon only if it has the exact energy needed to move to another energy level

The energy required to move an electron in a hydrogen atom from energy level 1 to energy level 2 is: a. 13.1 eV. b. 13.6 eV. c. 10.2 eV. d. 12.1 eV. e. 12.75 eV.

c. 10.2 eV

Which of the following is NOT one of Kirchhoff's laws? a. A low-density, hot gas emits an emission spectrum. b. A low-density, cool gas absorbs photons from a continuous source, creating an absorption spectrum. c. A low-density, cool gas in isolation creates a continuous spectrum. d. A luminous solid, liquid, or dense gas emits a continuous spectrum.

c. A low-density, cool gas in isolation creates a continuous spectrum

Which of the following can not be determined directly from spectral-line analysis? a. Line-of-sight velocity b. Temperature c. Distance d. Composition

c. Distance

What is the most obvious and important way in which the characteristic spectra of atoms differ from those of molecules? a. Molecular spectra are much dimmer than the characteristic spectra of the atoms of which they are composed. b. Molecular spectra are generally far simpler than the characteristic spectra of the atoms of which they are composed. c. Molecular spectra are generally far more complex than the characteristic spectra of the atoms of which they are composed. d. Molecular spectra fade more quickly with distance than do atomic spectra. e. Molecular spectra are much brighter than the characteristic spectra of the atoms of which they are composed.

c. Molecular spectra are generally far more complex than the characteristic spectra of the atoms of which they are composed.

The observed spectral lines of a star are all shifted towards the red end of the spectrum. Which statement is true? a. The second law of Kirchhoff explains this. b. The star has a radial velocity towards us. c. This is an example of the Doppler effect. d. The star is not rotating. e. This is an example of the photoelectric effect.

c. This is an example of the Doppler effect

Which of the following cannot be determined spectroscopically? a. Pressure b. Rotation rate c. Transverse motion d. Magnetic field strength

c. Transverse motion

Emission lines of hydrogen that are found in the ultraviolet part of the electromagnetic spectrum are formed by electrons transitioning from: a. level 2 to any level. b. level 1 to any level. c. any level to level 1. d. any level to level 3. e. any level to level 2.

c. any level to level 1

Which of the following statements about the visible spectrum of the light emitted by the Sun is true? a. It consists of a smooth blackbody curve corresponding to a temperature of 6300 K, with no other prominent absorption or emission features. b. It consists of hundreds of bright emission lines that cluster near the middle of the visible region. c. It consists of hundreds of dark absorption lines superimposed on a bright continuous spectrum that peaks in the yellow, near the center of the visible region. d. It consists of a few dark absorption lines on a continuous spectrum that is otherwise independent of wavelength. e. It consists of a few bright lines widely separated from each other, mostly in the yellow portion of the visible range.

c. it consists of hundreds of dark absorption lines superimposed on a bright continuous spectrum that peaks in the yellow, near the center of the visible region

Compared with a star having many blue absorption lines, a star with many red and blue absorption lines must be a. moving away from the observer. b. moving away from the other star. c. of different composition than that of the other star. d. cooler than the other star.

c. of different composition than that of the other star

A hydrogen atom consists of an electron and a(n): a. lepton. b. ion. c. proton. d. neutron. e. neutrino.

c. proton

Compared with a spectrum from a ground-based observation, the spectrum of a star observed from above Earth's atmosphere would show a. no absorption lines. b. fewer emission lines. c. slightly fewer absorption lines. d. many more absorption lines.

c. slightly fewer absorption lines

The classical model of the hydrogen atom that explains its spectral line structure is due to: a. Kirchhoff. b. Mendeleev. c. Newton. d. Bohr. e. Fraunhofer.

d. Bohr

For hydrogen, the transition from the second to the fourth energy level produces: a. an ultraviolet absorption line. b. a violet emission line. c. a red emission line. d. a blue green absorption line. e. an infrared emission line.

d. a blue green absorption line

Molecules produce spectral lines by ________. a. electron transitions within the molecule b. changes in molecular rotation c. changes in molecular vibration d. all of the ways listed.

d. all of the ways listed

Figure 4.3 in the textbook ("Elemental Emission") shows the emission spectrum of neon gas. If the temperature of the gas was increased, we would observe a. even more red lines. b. fewer red lines and more blue lines. c. some faint absorption features. d. no significant change.

d. no significant change

In Bohr's model of the atom, electrons: a. are not confined to specific orbits. b. move from orbit to orbit in many small steps. c. are spread uniformly through a large, positive mass. d. only make transitions between orbitals of specific energies. e. can be halfway between orbits.

d. only make transitions between orbitals of specific energies

Since the difference in energy between the different rotational states in a molecule is very small, many molecular lines can be observed with: a. ultraviolet balloons flying above the ozone layer. b. high energy observatories like Chandra, in orbit above our atmosphere. c. visible light spectrometers. d. radio or microwave telescopes e. infrared telescopes on mountaintops.

d. radio or microwave telescopes

Which of the following type of electromagnetic radiation has the highest energy? a. visible b. infrared c. radio d. X-ray e. ultraviolet

d. x-ray

The ________ explains why the spectral lines from a rapidly rotating star are broader than those from a slowly rotating star.

doppler effect

The broadening of spectral lines can be caused by: a. density of the hot medium. b. rotation of the star. c. magnetic fields of the star. d. thermal motion of the hot atoms. e. All of the above

e. All of the above

What information about an astronomical object can be determined by observing its spectrum? a. its radial motion b. its chemical composition c. whether it has a strong magnetic field d. its temperature e. All of the above

e. All of the above

Spectral lines are often referred to as the stars' "fingerprints" because: a. both are unique to their source. b. both can be easily categorized c. both are characteristic of the individual that produced them. d. fingerprints also consist of individual lines that make a pattern. e. All of these are correct.

e. All of these are correct

In non-ionized hydrogen, for instance, what does a higher orbital state have more of than a lower orbital state? a. Electrons b. Charge c. Neutrons d. Protons e. Energy

e. Energy

The three laws dealing with the creation of various spectra are due to: a. Newton. b. Bohr. c. Einstein. d. Fraunhofer. e. Kirchhoff.

e. Kirchhoff

Why are molecular lines more complex than elemental spectral lines? a. Molecules have two or more atoms. b. Molecules are the basis of life. c. Most of the universe is made of molecules, not individual atoms. d. Molecules are heavier than atoms. e. Molecules can vibrate and rotate as well

e. Molecules can vibrate and rotate as well

Which of the following is NOT a true statement about atomic structure? a. An ion is an atom that has either gained or lost electrons. b. Transitions between two energy levels can occur only at one specific photon energy. c.An atom is in an excited state if it has at least one electron at a greater than normal distance from its parent nucleus. d. Atoms do not always remain in their lowest energy state. e. Transitions to levels either higher or lower in energy can occur from the ground state.

e. Transitions to levels either higher or lower in energy can occur from the ground state.

Which of these is the classic continuous spectrum? a. a fluorescent light b. a glowing nebula, such as M-42 c. sunlight d. a neon light e. a rainbow

e. a rainbow

The particle which adds mass but no charge to the atomic nucleus is the: a. proton. b. alpha particle. c. positron. d. neutrino. e. neutron

e. neutron

A(n) ________ spectrum is created by a glowing, hot thin gas, such as M-42 in Orion.

emission

All Lyman emission lines are transitions from the excited state to ________ state.

ground

True or False he broader the spectral line, the higher the pressure of the gas that is creating it.

True

True or false A cool, thin gas produces absorption lines.

True

see 60

see #60

________ is the process of stripping electrons from their atoms.

Ionization

________ is the scientific study of the distribution of electromagnetic waves by energy and how these patterns are created in atoms and molecules.

Spectroscopy

True or False An X-ray photon has more energy than a visible photon.

True

True or False If a fire truck's siren is rising in pitch, it must be approaching us.

True

True or False In our Sun, the spectral lines of hydrogen are weak, compared to their appearance in hotter stars.

True

True or False In the Bohr model, the transitions of electrons down to ground state produce the Lyman lines in the ultraviolet.

True

True or False Only a hot, thin gas can produce an emission line.

True

True or False The absorption lines for a cool thin gas are identical in color and energy to the emission lines of the same gas if hot enough to glow.

True

True or False The line intensity of a spectrum depends both on the abundance of a particular element and its temperature as well.

True

True or False The spectral lines of each element are distinctive to that element, whether we are looking at emission or absorption lines.

True

A cool, dilute gas between an observer and a continuous hot source will produce which of the following effects? a. Dark absorption lines will appear in the spectrum. b. The peak of the continuous spectrum will be shifted toward higher frequencies. c. Bright emission lines will appear in the spectrum. d. The spectral lines will be broadened by the heat from the source. e. The peak of the continuous spectrum will be shifted toward lower frequencies.

a. Dark absorption lines will appear in the spectrum

Compared with cooler stars, the hottest stars have absorption lines that are a. broad and fuzzy. b. thin and distinct. c. identical to the lines in the cooler stars.

a. broad and fuzzy

Compared with slowly rotating stars, the fastest spinning stars have absorption lines that are a. broad and fuzzy. b. thin and distinct. c. identical to the lines in the slowly rotating stars

a. broad and fuzzy

An incandescent light (glowing tungsten filament) produces: a. a continuous spectrum, with the peak giving the temperature of the filament. b. an absorption spectrum, with dark lines due to the solid filament. c. an emission spectrum, with bright lines due to ionized tungsten. d. a continuum, with bright tungsten lines added. e. a continuum, with dark lines of tungsten and argon as well.

a. continuous spectrum, with the peak giving the temperature of the filament

An atom that has been ionized: a. has more protons than electrons. b. has equal numbers of protons and electrons. c. is radioactive. d. is electrically neutral.

a. has more protons than electrons

The Balmer Beta absorption line is a result of a transition of an electron in a hydrogen atom from: a. level 2 to level 4. b. level 3 to level 2. c. level 4 to level 2. d. level 2 to level 3. e. None of the above

a. level 2 to level 4

If the rest wavelength of a certain line is 600 nm, but we observe it at 594 nm, then: a. the source is approaching us at 1 % of the speed of light. b. the source is getting 1% hotter as we watch. c. the source is approaching us at 0.1 % of the speed of light. d. the source is receding from us at 10% of the speed of light. e. the source is spinning very rapidly, at 1% of the speed of light

a. the source is approaching us at 1% of the speed of light

What does a blueshifted spectrum indicate? a. The source is moving to your left. b. The source is moving toward you. c. The source is moving away from you. d. The source is not moving. e. The source is moving to your right.

b. The source is moving toward you.

The splitting of spectral lines in the presence of strong magnetic fields is the: a. photoelectric effect. b. Zeeman effect. c. Second Law of Kirchhoff. d. Doppler effect. polarization of sunlight.

b. Zeeman effect

A neon light (thin hot neon gas in a sealed tube) gives us: a. a continuum, with dark lines identifying the neon atoms that are present. a few bright emission lines, telling us the gas is neon. nothing visible to us, but a lot of infrared lines as heat. a continuous spectrum, since the neon is hot enough to glow. a lot of random bright red lines due to the motion of the hot atoms.

b. a few bright emission lines, telling us the gas is neon

The Orion Nebula, M-42, is a hot, thin cloud of glowing gas, so its spectrum is: a. a continuum, strongest in the color red. b. a few bright lines against a dark background. c. a few dark lines in the continuum. not in the visible portion of the spectrum. d. a continuum, but with both bright and dark lines mixed in.

b. a few bright lines against a dark background

Typical stellar spectra appear as: a. a very redshifted rainbow due to the expansion of the universe. b. a rainbow, but with some dark lines mixed in. c. a rainbow with some bright lines on top of the continuum. d. an unbroken rainbow of colors. e. a series of bright, colored lines.

b. a rainbow, but with some dark lines mixed in

In a hydrogen atom, a transition from the third to the second energy level will produce: a. an infrared emission line. b. a red emission line. c. an ultraviolet absorption line. d. a blue green absorption line. e. a violet emission line

b. a red emission line

To have a negative ion, you must have: a. added a positron to the outer electron shell. b. added an electron to the outer electron shell. c. added a positron to the nucleus. d. taken away a proton from the nucleus. e. None of these; only positive ions can exist in nature.

b. added an electron to the outer electron shell

The particles which enter into chemical reactions are the atom's: a. protons b. electrons. c. neutrons. d. positrons. e. mesons.

b. electrons

Compared with a complex atom like neon, a simple atom such as hydrogen has a. more excited states. b. fewer excited states. c. the same number of excited states

b. fewer excited states

The element first found in the Sun's spectrum, then on Earth 30 years later, is: a. solarium. b. helium. c. technetium. d. hydrogen. e. aluminum.

b. helium

Which of the following type of electromagnetic radiation has the lowest energy? a. infrared b. radio c. visible d. ultraviolet e. X-ray

b. radio

The spectra of molecules are more complex because molecules can vibrate and ________ instead of just exhibiting electronic transitions like atoms.

rotate

The emission line for a given atom shows spectral features at the ________ location as in its absorption spectrum.

same

see # 10

see #10

see #17

see #17