a. what evidence have you discovered to explain why lava flowing out of a volcano becomes igneous rock?

Brief Explanations:

When lava cools and solidifies outside a volcano, it undergoes a process called solid - state crystallization. Magma (lava when it reaches the surface) is a molten mixture of minerals, gases, etc. As it cools, the atoms and molecules slow down and arrange themselves into an ordered structure, forming igneous rock. Evidence can include the texture of the rock (e.g., fine - grained if it cooled quickly), and the presence of certain minerals that form under specific cooling conditions.

Answer:

Evidence can include rock texture (fine - grained for rapid cooling) and mineral composition formed under specific cooling conditions.