Final answer:
The statement is true; a plutoid is a type of trans-neptunian dwarf planet that orbits the sun within the Kuiper belt and is nearly spherical in shape.
Step-by-step explanation:
The statement that a plutoid is a trans-neptunian dwarf planet which is round and orbits the sun in the Kuiper belt is true.
Plutoids are a category of dwarf planets that indeed orbit beyond Neptune, typically within the Kuiper belt - a region beyond Neptune filled with many small icy bodies.
As of the criteria defined by the International Astronomical Union (IAU), a dwarf planet is a celestial body that:
- Is in orbit around the Sun,
- Has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
- Has not cleared the neighborhood around its orbit (the primary distinction from a "true" planet).
Pluto, Eris, and Makemake are examples of such objects that are classified as dwarf planets. In 2006, the definition of a planet was revised, which led to the reclassification of Pluto from a planet to a dwarf planet.
The largest known objects in the Kuiper belt, including Pluto, Eris, Haumea, and Makemake, are categorized as dwarf planets and are distinct from both terrestrial and giant planets in our solar system.