1' The formula for the retention ofatmospheric gases on planets must also be valid for atmospheres on moons. Titan is observed to have an atmosphere. The mass ofTitan is 1.35 X 1023 kg and its radius is 2.57 X 103km. Its surface temperature is estimated to be 94K. The table below gives some molecules that are common in the Solar System. Which molecules could Titan retain against thermal escape? Molecule M (in atomic mass units) H2 2 He 4 CH4 l6 NH3 17 H20 18 N2 28 Oz 32 C02 44 (Marks: 4)