Nitpick: Dwarf planets are not a type of planet, but in fact a wholly separate category.
From Wikipedia: "In 2006 the concept was adopted by the International Astronomical Union (IAU) as a category of sub-planetary objects, part of a three-way recategorization of bodies orbiting the Sun: planets, dwarf planets and small Solar System bodies. […] Since 2006 the IAU and perhaps the majority of astronomers have excluded them from the roster of planets." https://en.wikipedia.org/wiki/Dwarf_planet
I remember Halley's comet from like 5th/6th grade. It was such a big deal at the time. But for all these years I thought it was Hailey's comet. Lol I guess I learned something today!
When I put the "The asteroid belt" it is not coming up as valid answer - what's up with that? Seems to be an error in your system. Asteroid does not come up either.
From Wikipedia: "In 2006 the concept was adopted by the International Astronomical Union (IAU) as a category of sub-planetary objects, part of a three-way recategorization of bodies orbiting the Sun: planets, dwarf planets and small Solar System bodies. […] Since 2006 the IAU and perhaps the majority of astronomers have excluded them from the roster of planets." https://en.wikipedia.org/wiki/Dwarf_planet
I mean, CO2 already is for Carbon Dyoxide