Question 1

Emission nebula take up about how much of the Milky Way Galaxy?

Accepted Answer

A) 1% 
B) 5% 
C) 10% 
D) 99% 
E) 100% 
A) 1% 
B) 5% 
C) 10% 
D) 99% 
E) 100%

Question 2

The polarization of light passing though the dust grains shows that:

Accepted Answer

A) the dust grains are elongated in shape. 
B) the dust grains are aligned by a weak interstellar magnetic field. 
C) the dust grains are chiefly made of iron. 
D) Both A and B are correct. 
E) All of the above are correct. 
A) the dust grains are elongated in shape. 
B) the dust grains are aligned by a weak interstellar magnetic field. 
C) the dust grains are chiefly made of iron. 
D) Both A and B are correct. 
E) All of the above are correct.

Question 3

We often find dark nebulae associated with bright H II regions.

Accepted Answer

A) True 
 B)False

Question 4

The most common molecule in a molecular cloud is:

Accepted Answer

A) methane, $\mathrm { CH } _ { 4 } .$ 
B) molecular hydrogen, $\mathrm { H } _ { 2 }$ 
C) carbon monoxide, CO. 
D) water, $\mathrm { H } _ { 2 } \mathrm { O } .$ 
E) ammonia, $\mathrm { NH } _ { 3 } .$ 
A) methane, $\mathrm { CH } _ { 4 } .$ 
B) molecular hydrogen, $\mathrm { H } _ { 2 }$ 
C) carbon monoxide, CO. 
D) water, $\mathrm { H } _ { 2 } \mathrm { O } .$ 
E) ammonia, $\mathrm { NH } _ { 3 } .$

Question 5

Due to absorption of shorter wavelengths by interstellar dust clouds, distant stars appear:

Accepted Answer

A) bluer. 
B) brighter. 
C) redder. 
D) larger. 
E) to have a higher radial velocity. 
A) bluer. 
B) brighter. 
C) redder. 
D) larger. 
E) to have a higher radial velocity.

Question 6

The relative density of dust to gas is least in which place?

Accepted Answer

A) the interstellar medium 
B) dark nebulae 
C) the atmosphere of Earth 
D) molecular clouds 
E) reflection nebulae 
A) the interstellar medium 
B) dark nebulae 
C) the atmosphere of Earth 
D) molecular clouds 
E) reflection nebulae

Question 7

Emission nebulae appear red because they are associated with cool red giant stars.

Accepted Answer

A) True 
 B)False

Question 8

List the four different ways that molecules can be excited to produce spectra.

Accepted Answer

In addition to becoming excite

Question 9

Which of the following has NOT yet been observed in space?

Accepted Answer

A) formaldehyde 
B) methyl alcohol 
C) DNA 
D) ammonia 
E) hydrogen cyanide 
A) formaldehyde 
B) methyl alcohol 
C) DNA 
D) ammonia 
E) hydrogen cyanide

Question 10

Ionization of hydrogen in H II regions is most visible at

Accepted Answer

A) 12,367 nm, the Paschen alpha line. 
B) 656.3 nm, Balmer alpha line for 3-2 electron transition. 
C) 21 cm in the radio region for the spin-flip of its electron. 
D) 121.3 nm, the Lyman alpha ultraviolet line for 2-1 electron transition. 
E) 473.2 nm, the blue-green emission line for 4-2 electron transition. 
A) 12,367 nm, the Paschen alpha line. 
B) 656.3 nm, Balmer alpha line for 3-2 electron transition. 
C) 21 cm in the radio region for the spin-flip of its electron. 
D) 121.3 nm, the Lyman alpha ultraviolet line for 2-1 electron transition. 
E) 473.2 nm, the blue-green emission line for 4-2 electron transition.

Question 11

How do we know that a hot main sequence star (and not some other kind of star)is embeddedin a cloud of interstellar gas?

Accepted Answer

Except for white dwarfs, all hot stars a

Question 12

Contrast the sizes of molecular clouds with emission nebulae.

Accepted Answer

The emission nebula are only a few light

Question 13

A large gas cloud in the interstellar medium that contains several type O and B stars wouldappear to us as:

Accepted Answer

A) a dark nebula. 
B) an emission nebula. 
C) bright blue. 
D) a reflection nebula. 
E) a dark patch against a bright background. 
A) a dark nebula. 
B) an emission nebula. 
C) bright blue. 
D) a reflection nebula. 
E) a dark patch against a bright background.

Question 14

What is the temperature of the gas in the dark dust clouds, and why is this important tomolecule formation?

Accepted Answer

The gas is about 100

Question 15

Why are so few molecules observed in visible light? Where are most observed, and why?

Accepted Answer

Few molecules, such as TiO, are durable

Question 16

What color is an H I region?

Accepted Answer

A) red from ionized hydrogen's alpha transition, such as in the Orion Nebula 
B) red from reddening due to dust 
C) colorless; it emits in the radio region 
D) blue from the scattering of light off the tiny atoms, such as around the Pleiades 
E) blue from ionized helium's alpha transition, such as the Horsehead Nebula 
A) red from ionized hydrogen's alpha transition, such as in the Orion Nebula 
B) red from reddening due to dust 
C) colorless; it emits in the radio region 
D) blue from the scattering of light off the tiny atoms, such as around the Pleiades 
E) blue from ionized helium's alpha transition, such as the Horsehead Nebula

Question 17

Interstellar dust clouds are best observed at what wavelength?

Accepted Answer

A) radio and infrared 
B) visible only 
C) UV and infrared 
D) radio and X-ray 
E) visible and UV 
A) radio and infrared 
B) visible only 
C) UV and infrared 
D) radio and X-ray 
E) visible and UV

Question 18

Which of these is NOT a consequence of dust in the interstellar medium?

Accepted Answer

A) reddening of stars' light that passes through the dust 
B) blue reflection nebulae around the Pleiades 
C) red light from the emission nebulae 
D) the dark nebulae that block 90% of the Milky Way from us visually 
E) terrestrial planets like our own 
A) reddening of stars' light that passes through the dust 
B) blue reflection nebulae around the Pleiades 
C) red light from the emission nebulae 
D) the dark nebulae that block 90% of the Milky Way from us visually 
E) terrestrial planets like our own

Question 19

Dark dust clouds radiate mainly in the radio portion of the electromagnetic spectrum.

Accepted Answer

A) True 
 B)False

Question 20

When an electron in H changes its spin from the same to the opposite direction as the proton,it:

Accepted Answer

A) emits an X-ray photon. 
B) absorbs a radio wave photon. 
C) emits a radio wave photon. 
D) absorbs a visible light photon. 
E) neither emits nor absorbs a photon. 
A) emits an X-ray photon. 
B) absorbs a radio wave photon. 
C) emits a radio wave photon. 
D) absorbs a visible light photon. 
E) neither emits nor absorbs a photon.

Exam 18: The Interstellar Medium: Gas and Dust Among the Stars

Emission nebula take up about how much of the Milky Way Galaxy?

The polarization of light passing though the dust grains shows that:

We often find dark nebulae associated with bright H II regions.

The most common molecule in a molecular cloud is:

Due to absorption of shorter wavelengths by interstellar dust clouds, distant stars appear:

The relative density of dust to gas is least in which place?

Emission nebulae appear red because they are associated with cool red giant stars.

List the four different ways that molecules can be excited to produce spectra.

Which of the following has NOT yet been observed in space?

Ionization of hydrogen in H II regions is most visible at

How do we know that a hot main sequence star (and not some other kind of star)is embeddedin a cloud of interstellar gas?

Contrast the sizes of molecular clouds with emission nebulae.

A large gas cloud in the interstellar medium that contains several type O and B stars wouldappear to us as:

What is the temperature of the gas in the dark dust clouds, and why is this important tomolecule formation?

Why are so few molecules observed in visible light? Where are most observed, and why?

What color is an H I region?

Interstellar dust clouds are best observed at what wavelength?

Which of these is NOT a consequence of dust in the interstellar medium?

Dark dust clouds radiate mainly in the radio portion of the electromagnetic spectrum.

When an electron in H changes its spin from the same to the opposite direction as the proton,it:

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The Copernican Revolution: The Birth of Modern Science

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Spectroscopy: the Inner Workings of Atoms

Telescopes: The Tools of Astronomy

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Earth: Our Home in Space

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Venus: Earths Sister Planet

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Jupiter: Giant of the Solar System

Saturn: Spectacular Rings and Mysterious Moons

Uranus and Neptune: The Outer Worlds of the Solar System

Solar System Debris: Keys to Our Origin

Exoplanets: Planetary Systems Beyond Our Own

The Sun: Our Parent Star

The Stars: Giants, Dwarfs, and the Main Sequence

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Stellar Evolution: The Life and Death of a Star

Stellar Explosions: Novae, Supernovae, and the Formation of the Elements

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The Early Universe: Toward the Beginning of Time

Life in the Universe: Are We Alone

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