Question 3

Solids do not always sink in liquids; it depends on the density of the solid and liquid.

The behavior of solids in liquids is determined by their relative densities. If a solid is less dense than the liquid, it will float, while a solid that is denser will sink.

A) True, a solid is hard, and liquids are not.

This statement is incorrect because the hardness of a solid does not determine whether it sinks or floats. The key factor is the density comparison between the solid and the liquid, not the physical state or hardness.

B) True, solids are heavier than liquids.

This option is misleading. While many solids are heavier than the same volume of liquid, weight alone does not dictate whether an object will sink or float. It is the density that matters; a solid can be lighter than a liquid if its density is lower.

C) False, solids have a smooth surface so they will float.

This statement is false. The surface texture of a solid does not influence its buoyancy. Floating or sinking is based on density rather than surface characteristics, so a solid can sink regardless of whether it has a smooth surface or not.

D) False, it depends on the density of the solid and liquid.

This is the correct answer. The principle of buoyancy states that whether a solid sinks or floats in a liquid depends on the relative densities of the solid and the liquid. If the solid's density is lower than that of the liquid, it will float; if it is higher, it will sink.

Conclusion

The correct answer is D, as it accurately reflects the principle of buoyancy and density. Options A, B, and C fail to consider the fundamental concept of density, which ultimately determines whether a solid will sink or float in a liquid. Understanding density is crucial to grasping the behavior of solids in liquids.