To determine which substance is a solid, we need to understand the physical states described for each object:
1. Object 1: "Slide past each other" indicates that the atoms are not in a fixed position but can move around each other. This behavior is characteristic of a liquid state, where the particles are close together but not in a rigid structure.
2. Object 2: "Are very viscous" suggests that the substance is thick and flows slowly. This description typically applies to a highly viscous liquid, not a solid. Viscosity is a measure of a fluid's resistance to flow.
3. Object 3: "Form a crystal" indicates that the atoms are arranged in a well-ordered, repeating pattern. This orderly structure is characteristic of a solid, as solids have a definite shape and volume due to the rigid arrangement of their atoms or molecules.
4. Object 4: "Spread out to fill their container" signifies that the atoms are in constant random motion and occupy the entire available space. This description corresponds to a gaseous state, where particles are far apart and move freely.
Given these descriptions, the substance that is a solid is Object 3, as it forms a crystal, which is a typical property of solids.
