To determine which of the substances is a solid, we need to examine the descriptions provided for each object and match them to our knowledge of the properties of solids, liquids, and gases.
1. Object 1: Slide past each other
- This description fits the properties of a liquid. In liquids, molecules slide past each other, allowing the substance to flow and take the shape of its container.
2. Object 2: Are very viscous
- Viscosity refers to a liquid's resistance to flow. A highly viscous substance flows slowly. Therefore, this description also points to a liquid, just a thick one like molasses or honey.
3. Object 3: Form a crystal
- The formation of crystals is characteristic of solids. In a solid, the atoms are arranged in a specific, ordered pattern, typically forming a crystal lattice.
4. Object 4: Spread out to fill their container
- This is a characteristic of gases. Gas molecules move freely at high speeds and spread out to fill the volume of their container.
Given these descriptions, the substance that forms a crystal (Object 3) fits the definition of a solid. Therefore, the solid substance is Object 3.
Final Answer: Object 3
