A volcanic <em>eruption</em> occurs when the <em>pressure </em> in a magma <em>chamber</em> becomes so great it is released like a valve. Magma is released through the volcano's <em>cone</em> in an eruption of <em>lava</em> rocks (bombs) and ash. A volcanic <em>cone</em> develops over centuries as flowing <em>lava</em> from the active volcano <em>cools </em>to form layers of rock.
Hope this works,
Ahawk
This is because oxygen (2.8.6) requires two electrons on its valence shell to attain stable configuration (2.8.8). Hydrogen (1) on the other hand requires one electron on its valence shell to attain stable configuration (2). Therefore in a covalent bond, it requires two hydrogen and one oxygen to share electrons and achieve stable configuration.
If you need half the volume, you need double the pressure (V * p). Normal air pressure in the atmosphere is 101300 Pa so that means you need double that, thus 202600 Pa (or 2,026 bars)
