Question

question 17
what is the relationship between texture and cooling rate?
smaller grains = slower cooling
larger grains = faster cooling
larger grains = slower cooling

question 18
what controls viscosity of lava?
temperature of lava
rate of cooling
minerals present in lava
all of the above

Explanation:

For Question 17: When magma cools slowly, there is more time for mineral crystals to grow, resulting in larger grains. When it cools quickly, crystals have less time to grow, leading to smaller grains.
For Question 18: Temperature affects the kinetic energy of lava - higher temperature means lower viscosity. Cooling rate can change the state and thus viscosity over time. Minerals present can affect the internal structure and flow - ability of lava, influencing viscosity.

Answer:

Question 17: Larger grains = slower cooling
Question 18: all of the above