Many galaxies with erupting black holes are found ____.

Many galaxies with erupting black holes are found ____.
 
  a. in poor clusters with little intergalactic gas
  b. isolated in space
 c. in one of a pair of orbiting galaxies
 d. very close to the Milky Way galaxy
 e. in the Local Group

Question 2

A continuous spectrum is produced by ____.
 
  a. atoms that become ionized
 b. electrons that transfer from a high energy level to a low energy level
  c. electrons that transfer from a low energy level to a high energy level
  d. the intensity of agitation of atoms in a hot gas
 e. the motion of an object toward or away from the observer

Question 3

Supermassive black holes erupt in ____.
 
  a. any type of galaxy, and at random times
 b. elliptical galaxies only, when the last of their gas and dust is consumed
  c. galaxies that have been part of a collision or merger
 d. spiral galaxies only, during a burst of star formation
 e. irregular galaxies

Question 4

Absorption lines are produced by ____.
 
  a. atoms that become ionized
 b. electrons that transfer from a high energy level to a low energy level
  c. electrons that transfer from a low energy level to a high energy level
  d. the intensity of agitation of atoms in a hot gas
 e. the motion of an object toward or away from the observer

Question 5

A supermassive black hole erupts when ____.
 
  a. it collides with a neutron star
 b. magnetic fields form tubes to channel the jets
 c. the accretion disk tilts to a new angle
 d. a sudden flood of matter flows inward producingan accretion disk
  e. starburst events irradiate the accretion disk with new energy

Question 6

Emission lines are produced by ____.
 
  a. atoms that become ionized
 b. electrons that transfer from a high energy level to a low energy level
  c. electrons that transfer from a low energy level to a high energy level
  d. the intensity of agitation of atoms in a hot gas
 e. the motion of an object toward or away from the observer