What is magma that is ejected from a volcano during an eruption called?

Magma that is ejected from a volcano during an eruption is referred to as tephra. Tephra encompasses all solid volcanic materials that are expelled into the atmosphere during an explosive volcanic event. This includes a range of particle sizes, from fine ash to larger volcanic rocks, and it can accumulate around the volcano or be dispersed over wide areas depending on the eruption's intensity.

Lava, on the other hand, is magma that has flowed out onto the Earth's surface after it erupts. While lava is a crucial aspect of volcanic activity, it differs from tephra in that tephra refers specifically to material expelled into the air. Ejecta is a more general term that can include various types of materials ejected during volcanic eruptions but is less specific than tephra in the context of volcanic processes. Quicksilver, or mercury, is not relevant in this context and does not relate to volcanic activity. Thus, tephra accurately captures the nature of the solid material expelled during an explosive eruption.