A helium weather balloon is used to lift a meteorological sensor package high up into the atmosphere. At Earth%u2019s surface it contains 3 m3 of helium at a pressure of 1 atmosphere. At the maximum height that the balloon reaches (~20 km), the volume of helium in the balloon expands to 42 m3. The temperature at the meteorological station where the balloon was released was 30 oC and at the balloon%u2019s maximum height, -56 oC.
a) Calculate the number of moles of helium in the balloon.
b) Find the atmospheric pressure the balloon experiences at its maximum height.