Final answer:
Viscous magmas and gases are more prone to explode during volcanic eruptions due to greater resistance to gas escape, resulting in higher pressure buildup. This can lead to explosive eruptions, propelling volcanic material into the air.
Step-by-step explanation:
Viscous magmas and gases are more prone to explode during volcanic eruptions. This is because volcanoes with more viscous (harder to flow) magmas have greater resistance to the gases trying to escape, leading to higher pressure buildup.
When the pressure becomes too high, an explosive eruption can occur, propelling volcanic material, such as larger fragments of rock and volcanic glass, into the air.