Earth
100 - This is the only place in the Solar System with plate tectonics.  (Earth)
200 - Earth's surface gives off radiation mostly in this region of the spectrum  (Infrared)
300 - The composition and phase of the outer core.  (Liquid iron alloy)
400 - Energy for Earth's tectonic activity is provided by primordial heat, and this process.  (Radioactive decay)
500  - One of two processes responsible for the relative absence of craters on Earth's surface.   (Erosion, plate tectonics)

Venus, Mars
100 - The dominant gas in Venus' atmosphere.  (Carbon dioxide)
200 - The dominant gas in Mars' atmosphere.  (Carbon dioxide)
300 - Venus is so hot because this type of radiation cannot escape directly from the surface into space.  (Infrared)
400 - The unusually high abundance of this isotope in its atmosphere suggests a large abundance of past water on Venus.  (Deuterium)
500 - The abundance of this mineral was the main reason Opportunity landed on Meridiani Planum.  (Hematite)

Jupiter, Saturn
100 - The dominant element comprising Jupiter and Saturn.  (Hydrogen)
200 - Shoemaker-Levy 9 was a member of this class of object.  (Comet)
300 - Saturn's rings are made up mostly of this general material.  (Ice)
400 - The hydrogen in the interiors of Jupiter and Saturn takes this form at the extreme pressures present there.  (Metal)
500 - The name of the powdery substance that comprises Jupiter's rings.  (Regolith)

Uranus, Neptune 
100 - This planet was discovered by its effects on Uranus's orbit.  (Neptune)
200 - The approximate tilt of Uranus's spin axis to its orbital axis.  (90 degrees)
300 - This molecular gas is seen in Uranus's atmosphere.  (Methane)
400 - Uranus' rings were discovered by carefully studying light from this kind of object (Star)
500 - This molecule is present in ionic form in Uranus' interior.  (Ammonia)

Moon
200 - Of the two regions on the moon, this is the least heavily cratered.  (Maria)
400 - For every time the Moon orbits Earth, it spins on its axis this many times.  (Once)
600 - The moon's phase when it rises at sunset.  (Full)
800 - The Moon's surface is most similar to that of this other body in the solar system.  (Mercury)
1000 - The part of the Earth that the Moon is most similar to in its composition.  (Mantle)

Other Moons
200 - This moon's volcanoes are powered by tidal interaction with Jupiter.  (Io)
400 - This moon has clouds, a thick atmosphere, and erosion patterns on its surface. (Titan)
600 - Probably the most likely candidate world for extraterrestial life in the Solar Sys. (Europa)
800 - The order of Jupiter's Galilean satellites, from nearest to farthest. (Io, Europa, Ganymede, Callisto)
1000 - This moon is doomed to destruction within the next few hundred million years.  (Triton)

Sun 
200 - Currently, the Sun generates energy by nuclear reactions involving this element. (Hydrogen)
400 - The approximate percentage of the solar system's matter contained within the Sun (99.9%)
600 - The final stage of the Sun's evolution is a tiny star known by this name.  (White dwarf)
800 - The heaviest element a sunlike star will ever produce.  (Oxygen)
1000 - Neither fission nor fusion reactions involving this element can release energy.  (Iron)

Extremes of the Solar System
200 - The largest planet in the Solar System.  (Jupiter)
400 - The hottest planet in the Solar System.  (Venus)
600 - The most volcanically active body in the solar system.  (Io)
800 - The planet with the largest volcano in the Solar System.  (Mars)
1000 - The largest moon in the Solar System.  (Ganymede)

Squishy Moving Things
By most counts, the dominant form of life on Earth.  (Bacteria)