The Asteroid Belt is a demarcation between the gas giants and terrestrial type planets.
We have no idea which particular three categories you mean. One possibility is "terrestrial planets", "gas giants", "ice giants". There are others. For example, ice dwarfs, gas dwarfs ("dwarf" in this sense means "less than 10x Earth's mass", and is not related to the term "dwarf planet" used to describe e.g. Pluto; Pluto is a dwarf in both senses, but Earth in only one of them). "hot Jupiters", chthonian planets ... Your question is impossible to answer, because there are a lot more than three categories, and which three are meant depends really on what you're trying to distinguish.
There are theories that claim the Earth was formed by many disdinct, huge rocks or "planets' crashed into each other. The crashes' fragments bonded by gravity, thus making a survivable planet. It is also said that the moon was formed when a premature planet crashed into Earth. The debris joined together into a body, and thus, led to the moon.
There is no reason to believe that he "won't ever" have more moons. On the contrary, it is quite possible that the gas giants - like Saturn - have gravitationally captured some asteroids, converting them into their moons - and this may happen again.
Jupiter and Saturn's atmospheric contents are 89% hydrogen, 11% helium, and traces of methane. Jupiter though also has traces of ammonia. Jupiter and Saturn are both Gas Giants, so their name really tells about what they're made of: gas of course!!! :)
Some are (the gas giants), but the others, like Earth, are not.
Yes, Neptune is more gaseous than Earth. It is one of gas giants. It has much more gas than Earth because it is not as close to the sun like the other gas giants.
It is earth-like, as opposed to the gas giants, if that's what you mean.
Uranus is one of the gas giants, but is not as big as some of the other gas giants, like Jupiter. Earth is far, far smaller than Uranus.
Yes. The winds of the gas giants are far faster than thos on Earth.
The gas giants are important because their strong gravity draws in many large asteroids before they can hit earth.
NO
Uranus, one of the four gas giants. Its tilted on its side by 98 degrees.
Saturn is one of the gas giants. As such it doesn't have a hard surface like Earth or Mars do.
The Gas Giants have a deep gas atmosphere and earth have a not so deep atmosphere
The Gas Giants have a deep gas atmosphere and earth have a not so deep atmosphere
Earth is a rocky planet because the gas giants are in the outer planets and earth is in the inner planet.