Why does volacanos erupt or explode?

Answer 1

well in volcanoes is magma, which when it is no longer in the volcano, is lava. and when a volcano is explosive, in the magma is silica. and silica makes the magma really sticky and thick. in a volcano, the magma comes out of vents at the top. and when magma with silica tries to comes out, it gunks up the vents to where they are clogged and nothing can get out of them. so when this happens, pressures pushes hard to try and get the magma out. then it pushes REALLY hard and it comes out even bigger and destructively! but when there is no silica in the magma, the magma just drizzles out of a volcano but its nonexplosive. hope this helps. and i know this is true. we just learned it in science class. I'm 11 years old but i am certain this is the correct accusation.