Would the terrestrial or jovian planets be least likely to hold on to atmospheric gases?
You actually answered your own question wither you realized it or not the terrestrial planets are less likely to hold on to gases cause there smaller Jupiter has a core under all the gas’s that is much larger than earths that’s why gas cannot escape its gravity (not even helium) For example if you take a helium balloon to Jupiter it will sink here it floats up. if you take and Oxygen filled balloon here and drop it it sinks. On mercury it would float up the same as a helium balloon on earth.
