The region of our solar system between Mercury and Mars has very few asteroids, while the region ...

The region of our solar system between Mercury and Mars has very few asteroids, while the region between Mars and Jupiter has many asteroids.
 
  Based on what you have learned, what is the most likely explanation for the lack of asteroids between Mercury and Mars? A) There were very few planetary leftovers in this region, because most of the solid material was accreted by the terrestrial planets as the planets formed.
  B) It was too hot for asteroids to form in this part of the solar system.
  C) Gravity was too weak to allow asteroids to form in this part of the solar system.
  D) All the asteroids that formed between Mercury and Mars later migrated to the asteroid belt between Mars and Jupiter.

Question 2

Compared to the density of water, our Earth averages about
 
  A) the same density, similar to Saturn.
  B) 3 times denser, much like our Moon.
  C) 4 times denser, similar to Mars.
  D) 5 times denser, like the Mercury and Venus.
  E) 10 times denser, due to our core of iron and nickel.

Question 3

Two red stars have surface temperatures of 3000 K, but Star A's luminosity is about 5 of the Sun's and Star B's luminosity is about 32,000 times the luminosity of the Sun. How much bigger is star B than star A?
 
  A) They are the same size.
  B) Star B's radius is about 16 times larger than star A's radius.
  C) Star B's radius is about 800 times larger than star A's radius.
  D) Star B's radius is about 640,000 times larger than star A's radius.
  E) This cannot be determined from the information given.

Question 4

Which type of star has the strongest stellar winds?
 
  A) giant K- and M-type stars
  B) white dwarfs
  C) dwarf K- and M-type stars
  D) main sequence O- and B-type stars
  E) T Tauri stars

Question 5

________ galaxies are essentially featureless; their light reveals evidence for the presence of only old red Main Sequence and red giant stars.
 
  Fill in the blank(s) with correct word

Question 6

The design of modern X-ray telescopes depends on:
 
  A) lenses made of germanium.
  B) the prime focus design, with mirrors made of iron.
  C) grazing incidence optics.
  D) achromatic lenses to keep the X-rays in focus.
  E) the Cassegrain design, with mirrors made of lead.

Question 7

In terms of temperature alone, there are ________ terrestrial planets within the widest boundaries of the Sun's zone of habitability.
 
  Fill in the blank(s) with correct word