Final answer:
According to scientific classification, Mercury is considered a planet, while both Pluto and Ceres are not. Pluto is classified as a dwarf planet, and Ceres is classified as a dwarf planet and the largest object in the asteroid belt.
Step-by-step explanation:
According to scientific classification, Mercury is considered a planet. It is the closest planet to the Sun and has a heavily cratered surface with no atmosphere. It is similar to the Moon in many ways, including lacking atmospheres, being deficient in geological activity, and being dominated by impact cratering. On the other hand, both Pluto and Ceres are not classified as planets. Pluto is now classified as a dwarf planet, distinct from the eight major planets, while Ceres is classified as a dwarf planet and the largest object in the asteroid belt.