Igneous rocks form from the cooling and solidification of lava or magma.
I'm not a big fan of this question, but I think the "desired" answer is grain-size (from very large to microcrystalline) and interlocking texture.
(It could be tendentiously argued that tuff (also called tufa) and possibly other pyroclastic rocks, which form from volcanic ejecta, lack an interlocking texture because they are more like sediments that are welded together. I say this is tendentious because such rocks are about as much sedimentary as they are igneous, and are not typical igneous rocks if they are igneous rocks at all.)
An explosion occurs when the timescale for the energy release by some process is much shorter than the timescale on which a system can adjust to damp the energy release process. In the present day Sun, nuclear fusion is a very slow process: on average it takes many billion years for a proton to fuse with another. This timescale is quite temperature dependent, so you might have thought the centre of the Sun might heat up quickly, leading to a runaway "explosion". However, an increase in temperature leads to an increase in pressure that would expand the Sun, reducing the core density and temperature and decreasing the rate of nuclear fusion again. The timescale for the Sun to react in this way is just millions of years, so this acts like a thermostat that keeps the reactions under control.
Reverse polarity - polarities are reversed so North becomes south and the other way around. so as said above, Earth's magnetic field lines up in a direction opposite of the present magnetic field.
it forms a major river system in Western Asia. Originating in the Armenian Highlands of eastern Turkey they flow through Syria and Iraq into the Persian Gulf.