To answer Oscar's meaning of life question...
Its 42 obviously.
Answers from Punk Science at the Science Museum....off the top of my head liquid nitrogen is -196 C and space is infinite. The rest will take some thinking-
Answers from Alex Nicholls
Liquid nitrogen reverts to gas (boils) @-196 C
Solid nitrogen reverts to liquid @-210 C
Most explosives have nitrates as their principal component. So gunpowder has saltpetre in it (potassium nitrate). Other well known explosives are TNT (tri nitro toluene) dynamite (nitro glycerene) and more recently PETN (penta ethyl tetra nitrate). Nitrates are relatively easy to break down into lots of hot gas. If you set fire to gunpowder sprinkled in a trail it will burn relatively gently, converting the solids into hot gases, but if it is in a confined space, the pressure and temperature build very quickly and the conversion occurs in a few milliseconds, creating a pressure wave which is the bang. Modern high explosives require a small explosion to set them off (a detonator) and just fire may well cause them to burn slowly but will not cause an explosion. When they do go off, the burn time is much less than a millisecond and the pressure wave is intense. Big bang, lots of destruction! Cordite is used to fire bullets since it burns relatively slowly, thus pushing the bullet up the barrel rather than blowing the gun to pieces. Relatively, since in a modern sniper's rifle it does accelerate a bullet weighing 45g from standstill to 1 km per second in 70cm, the length of the barrel! It still makes a "bang" as the pressure wave reaches our ears.