Q: Sodium is an example of what sort of thing that cannot exist by itself in nature? Read this paragraph and choose the correct option from the provided answers: Most of the elements we know about do not exist freely in nature. Sodium cannot be found by itself (unless we prepare it in the laboratory) because it interacts easily with other materials. On the other hand, the element helium does not interact with other elements to any extent. We can isolate helium from natural gas during the process of drilling for oil. Choices: - concept - compound - aspect - element A:
element

Q: What is a force that opposes motion between any surfaces that are touching? Read this paragraph and choose the correct option from the provided answers: Friction is a force that opposes motion between any surfaces that are touching. Choices: - vibration - tension - gravity - friction A:
friction

Q: What molecules are usually insoluble in water? Read this paragraph and choose the correct option from the provided answers: Non-polar molecules are usually insoluble in water. Choices: - polar - acids - ions - non-polar A:
non-polar

Q: A colloid is a homogeneous mixture with medium-sized what? Read this paragraph and choose the correct option from the provided answers: A colloid is a homogeneous mixture with medium-sized particles. Examples include homogenized milk and gelatin. The particles of a colloid are large enough to reflect light, so you can see them. But they are too small to settle or filter out of the mixture. Choices: - atoms - solutions - molecules - particles A:
particles