Question 1

What is the most abundant element in the interstellar medium?

Accepted Answer

A)  carbon 
B)  iron dust 
C)  carbon dust 
D)  helium 
E)  hydrogen

Question 2

The interstellar medium is composed of mainly _____.

Accepted Answer

A)  equal parts of gas and dust 
B)  mostly dust and some gas 
C)  mostly gas and some dust 
D)  dust only 
E)  gas only

Question 3

What observations indicate the presence of dust in the interstellar medium?

Accepted Answer

The answer of What observations indicate the presence of dust...

Question 4

Briefly discuss the gas-stars-gas cycle.

Accepted Answer

The answer of Briefly discuss the gas-stars-gas cycle....

Question 5

Which type of nebula is produced when a star, hotter than 25,000 K, excites the gas near it to produce an emission spectrum producing a distinctive pink color?

Accepted Answer

A)  emission nebulae 
B)  H I 
C)  reflection nebulae 
D)  dark nebulae 
E)  spectral type B6

Question 6

The pressure of a gas depends on the ____ and ____ of the gas.

Accepted Answer

A)  density; volume 
B)  temperature; density 
C)  temperature; mass 
D)  temperature; volume 
E)  density; mass

Question 7

What observations demonstrate the existence of an interstellar medium?

Accepted Answer

The answer of What observations demonstrate the existence of an...

Question 8

H II Regions are also called emission nebulae.

Accepted Answer

A) True 
 B)False

Question 9

To an observer on Earth, dust in the interstellar medium will cause a star to appear _______________ and_______________than it really is.

Accepted Answer

The answer of To an observer on Earth, dust in...

Question 10

The ground state of hydrogen has two closely-spaced energy levels, where oneelectron is spinning up and the other is spinning down. This energy transition corresponds to releasing excess energy as a photon at what wavelength?

Accepted Answer

A)  21 centimeters 
B)  21 millimeters 
C)  21 meters 
D)  22.2 centimeters 
E)  22.2 millimeters

Question 11

Why doesn't warm, dense hydrogen emit 21-cm radiation?

Accepted Answer

The answer of Why doesn't warm, dense hydrogen emit 21-cm...

Exam 10: The Interstellar Medium