(8%) problem 9: helium is a very important element for both industrial and research applications. in its gas form it can be used for welding, and since it has a very low melting point (only 0.95 k under 2.5 mpa) it can be used in liquid form to cool superconducting magnets, such as those found in particle physics experiments. say we have a cylinder of n = 125 moles of helium gas at room temperature (t = 20° c). the cylinder has a radius of r = 17 cm and a height h = 1.64 m. what pressure is helium gas under?