Well, the cause of a volcanic eruption is when the lower crust melts. This leads to the formation of magma. The volcano is an opening through which the magma is discharged. The rock inside the earth melts. This magma is diffused upwards through the volcano. If magma reaches the top of the volcano, it behaviour depends on viscosity. So what happens before a volcanic eruption is that the lower crust melts, causing the formation of magma, which is released through the volcano. Hope i helped.
Most likely the answer is water and a salt. When a strong acid and strong base react the OH and H form water and the cation from the base and anion from the acid forms a salt. I hope this helps. Let me know if anything is unclear.
Jovian planets are what we call the "gas giants," so immediately we can eliminate craters or volcanos because they don't have a solid surface. asteroids in space doesn't belong to any specific planet, so the answer is ring systems.
