# Video: Properties of Solids

Which one of the following is true for solids? [A] Solids keep their shape without a container to support them. [B] All solids are made of atoms in a regular lattice. [C] Solids cannot be compressed. [D] Solids are made of only one type of atom. [E] solids can only be mixed with other solids.

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### Video Transcript

Which one of the following is true for solids? A) Solids keep their shape without a container to support them. B) All solids are made of atoms in a regular lattice. C) Solids cannot be compressed. D) Solids are made of only one type of atom. Or E) solids can only be mixed with other solids.

This question is asking for the one true statement out of the five that applies to solids. Therefore, we’re looking for one true statement and four false statements.

Let’s start off by having a look at A. A says that solids keep their shape without a container to support them. So, here’s an empty container. What this suggests is that, if we have a solid inside a container, and then take the container away, the shape of the solid won’t change.

What we’re not talking about here is a powder. A powder is made up of lots of small samples of solid and behaves differently to a lump of solid. What we’re talking about here is a lump of solid. We know the statement is true by definition. Lumps of solid keep their shape regardless of the container. Solids keep their shape because of the strong bonds between the components. These strong bonds enforce a fixed shape. So, we found our answer, but let’s check the other statements just to be safe.

Statement B says that all solids are made of atoms in a regular lattice. Another term for a regular lattice is a crystal. However, there are solids which are not crystalline, such as amorphous carbon, wax, or glass. In these structures, spatial arrangements and bonding arrangements vary depending on where you’re looking. So, there is no regular lattice. A second argument against this point is that there are solids that are not made of atoms but are made of ions, for instance, sodium chloride. So, statement B is definitely false.

What about statement C? Statement C says that solids cannot be compressed. You should know that gases, liquids, and solids have decreasing compressibility. Gases have more space between their particles. So, they can be compressed more than liquids which have a little bit of space more than solids which have very very little. However, even though solids are the least compressible of these standard states, a little is more than none.

The statement says that solids cannot be compressed, but some solids can be compressed a little. Solid cesium has the award for the most compressible solid. It does take a lot of pressure. But, 7000 kilograms per square centimeter will reduce the size of cesium by 20 percent. That’s the same pressure as having an entire elephant on your fingernail. Therefore, statements C is false.

Now, on to statement D. Statement D says that solids are made up of only one type of atom. By which it means they contain only one element. However, there are solids containing more than one element, for instance, the primary constituent of sand, silicon dioxide. Therefore, statement D is also false.

Finally, we come to statement E. Statement E says that solids can only be mixed with other solids. However, there are many examples of mixtures that are mixtures of solids and liquids or solids and gases, for instance, suspensions of barium sulfate in water, or smoke in air. Therefore, statement E is also false.

So, of the five statements given, the only one that is true for solids is that solids keep their shape without a container to support them.