1. Outer planets - c. gaseous, spherical, cleared its neighborhood.
2. Density - f. amount of matter in an object, in a given space.
3. Orbital distance - e. Distance between any planet and the sun.
4. Mass - a. Amount of matter in an object.
5. Asteroid - b. Irregular rock orbiting between mars and Jupiter.
6. Volume - d. amount of space an object takes up.