In which of the following situations would the weak acid dissociate to the largest extent (i. e., have the largest percent dissociation)?

Large helium-filled balloons are used to lift scientific equipment to high altitudes. what is the pressure inside such a balloon if it starts out at sea level with a temperature of 10.0ºc and rises to an altitude where its volume is twenty times the original volume and its temperature is – 50.0ºc ? (assume atmospheric pressure is constant.)