GEOLOGY

Detailed explanation-1: -Gas gives magmas their explosive character, because the gas expands as pressure is reduced. Felsic magmas usually have higher gas contents than mafic magmas.

Detailed explanation-2: -The amount of gas in a magma is also related to the chemical composition of the magma. Rhyolitic magmas usually have higher gas contents than basaltic magmas.

Detailed explanation-3: -Composite volcanoes have steep slopes consisting of layers of lava and ash, and often have very explosive eruptions. This type of volcano is found along convergent boundaries and has a very high viscosity. The gas content is high, but the temperature is low.

Detailed explanation-4: -Explosive eruptions generally involve magma that is more viscous and has a higher gas content. Such magma is often shattered into pyroclastic fragments by explosive gas expansion during an eruption.