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Astro1 H.W.2

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 1. 
The neutral hydrogen atom consists of
a.
one proton and one neutron.
b.
one proton.
c.
one proton, one neutron, and one electron.
d.
one proton and one electron.
e.
an isotope and an ion.
 

 2. 
A neutral atom always contains
a.
the same number of protons as it does neutrons.
b.
the same number of electrons as it does neutrons.
c.
the same number of protons as it does electrons.
d.
twice as many protons as it does neutrons.
e.
twice as many neutrons as it does protons.
 

 3. 
The temperature of an object from which no heat energy can be extracted is
a.
0° F
b.
0° C
c.
0° K
d.
100° K
e.
100° C
 

 4. 
The Hγ line has a wavelength of 434.0 nm when observed in the laboratory. If the Hγ line appears in a stars spectrum at 434.5 nm, what is the radial velocity of the star?
a.
346 km/sec away from the observer.
b.
346 km/sec toward the observer.
c.
1.3 × 108 m/sec away from the observer.
d.
1.3 × 108 m/sec toward the observer.
e.
The radial velocity of the star can not be determined from this information.
 

 5. 
Absolute zero is
a.
zero degrees Celsius.
b.
the temperature at which atoms have no remaining energy from which we can extract heat.
c.
the temperature at which water freezes.
d.
both a and c
e.
none of the above
 

 6. 
The process of removing an electron from a stable nucleus is known as
a.
ionization.
b.
Doppler broadening.
c.
collisional broadening.
d.
a red shift.
e.
quantum mechanics.
 

 7. 
The ____ is responsible for binding the electrons to the nucleus.
a.
Kirchhoff's law
b.
ground state
c.
temperature
d.
Coulomb force
e.
Balmer series
 

 8. 
____ has a negative charge and a mass about 1800 times small than a proton.
a.
A neutron
b.
An electron
c.
A molecule
d.
A nucleus
e.
An isotope
 

 9. 
____ is a set of rules that describes how atoms and subatomic particles behave.
a.
Kirchhoff's law
b.
Black body radiation law
c.
The Coulomb force
d.
Quantum mechanics
e.
The binding energy
 

 10. 
Atoms that have the same number of protons but a different number of neutrons are called
a.
ions.
b.
molecules
c.
atomic pairs.
d.
nuclear pairs.
e.
isotopes.
 

 11. 
If you move an electron in an atom from a low energy level to a higher energy level within the atom, we say that the atom is
a.
in the ground state.
b.
ionized.
c.
dissociated.
d.
an excited atom.
e.
neutralized.
 

 12. 
At what wavelength would a star radiate the greatest amount of energy if the star has a surface temperature of 60,000 K?
a.
50 nm
b.
500 nm
c.
300 nm
d.
1.8 × 1011 nm
e.
180 nm
 

True/False
Indicate whether the statement is true or false.
 

 1. 
Blue stars are hotter than red stars.
 

 2. 
An absorption spectrum is also called a bright line spectrum.
 

 3. 
The Doppler effect is sensitive only to motion along the line of sight.
 

 4. 
Hydrogen lines are weak in the spectra of hot stars because many of the hydrogen atoms are ionized.
 

 5. 
An atom is ionized if one of its electrons jumps to a higher energy level in the atom.
 



 
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