Which term matches the definition: a liquids resistance to flow?

• A. Lava Flow
• B. Ash Fall
• C. Viscosity
• D. Pyroclastic Flow

Answer: (C)

A liquid’s resistance to flow is described by viscosity. Viscosity measures how thick or sticky a fluid is due to internal friction between its layers; higher viscosity means a slower, more resistant flow, while lower viscosity means a fluid flows more easily. In volcanic contexts, magma with high viscosity resists spreading and can trap gases, influencing eruption style, whereas low-viscosity magma flows readily. The other terms relate to specific volcanic phenomena rather than the property of resisting flow: lava flow is the movement of molten rock itself, ash fall is the deposition of volcanic ash, and pyroclastic flow is a fast-moving mixture of hot gas and volcanic material.