Because in the solid state, the molecules are packed tighter than in the liquid or gaseous states. Since density is mass per unit volume, you can can a greater mass in a smaller volume due to this tight packing, and thus, the density is greater.
Protactinium is a solid state of matter. Specifically, it is a dense, silvery-gray metal that is radioactive.
solid...
Gas is actually the least dense state of matter. In a gas, particles are spread out and have high energy causing them to move rapidly and take up a large volume. Solids are the most dense state because their particles are tightly packed together.
At room temperature uranium is a metal, solid, radioactive, dense.
The order is: - solid (the densest) - liquid - gas - plasma
A pencil is in the solid state of matter.
Solid
The density of solid substances is generally higher than that of liquids, which in turn are higher than gases. This is because the particles in a solid are tightly packed together, while in a liquid they are more spread out, and in a gas, they are far apart.
A sponge is usually in a solid state of matter.
Diamonds are a solid.
The least dense state of matter is plasma. Plasma is a collection of charged particles that have high energy levels and are not bound together in a solid, liquid, or gas state. It is the most common state of matter in the universe, found in stars and other highly energetic environments.
Solids are the most dense state of matter