If you mean in a year, then it's because it takes different times to circle the sun then planet earth (because they are more far away or closer).
They are small compared to other planets but big compared to us.
earth
In size and mass it is enormous compared to it's parent planet - The Earth.
it is mediam
some planets are bigger and some are smaller. some have different atmospheres. some of the planets are almost pure gas. some planets have as much as like 60 moons while ours only has one
The Inner planets are Mercury, Venus, Earth and Mars. They are the planets closest to the sun. They are similar in that they all have solid surfaces, are almost the same size and have at least one moon.
3rd
yes
Small
Because they are close together to the sun, compared to the other planets in the solar system.
Compared to other planets, yes it is small. But compared to a house, no, it is very large...
no, not compared to other planets around us. Think about it.