On a photograph of the Moon, the Moon measures 30 cm in diameter and a small crater measures 0.2 cm. ...

On a photograph of the Moon, the Moon measures 30 cm in diameter and a small crater measures 0.2 cm. The Moon's physical diameter is 1738 km. What is the physical diameter of the small crater?
 
  a. about 1738 km
  b. about 12 km
  c. about 520 km
  d. about 350 km
  e. about 3.5 km

Question 2

51 Pegasi is important because
 
  a. it is a pulsar with planets orbiting around it.
  b. it is a star with a planet that is known to support intelligent life.
  c. it is the largest satellite of Jupiter.
  d. it is the largest known asteroid.
  e. it is the first star like our Sun that was found to have a planet orbiting it.

Question 3

The uncompressed density of a planet in our solar system
 
  a. is greatest for the Jovian planets.
  b. is greatest for the planets closest to the Sun.
  c. is greatest for the planets furthest from the Sun.
  d. is greatest for the planets with the largest mass.
  e. is greatest of the planet with the largest radius.

Question 4

The most important effect in clearing the solar nebula of gas and dust was
 
  a. impacts by planetesimals.
  b. the solar wind.
  c. the Sun's magnetic field.
  d. the asteroid belt.
  e. radiation pressure.