Earth.
Earth is covered mostly in water, but is not made up mostly of water. Most of earth is made of rock.
The surface of planet Earth is made up of 71% water.
theprotoplasm of a cell is mostly made up of water.
Jupiter
Saturn is made up of hydrogen
It is mostly rock.
Gas, mostly Hydrogen and Helium.
Earth is mas mostly of silicate minerals with a core made mostly of iron and nickel.
Earth is the planet that fits this description. It contains approximately 70% water on its surface and its atmosphere is primarily composed of nitrogen, with oxygen being the second most abundant gas.
The surface of earth is covered mostly by water.
Pluto has a lot of frozen water, but it probably has more rock than ice. Anyway it's only a dwarf planet now. There are no other possible correct answers.
Check your grammar. A planet isn't alive it's mostly made up of inorganic matter.