Question

Which gases were so light they escaped the gravitational pull of early Earth?

Answer 1

`H_2`

Explanation:

Earth is pretty-much a closed system. The main thing we receive from outside earth is sunlight (radiation) and foreign objects (meteorites etc.).

Then in terms of what we lose, we tend to only lose infrared radiation, which is what the Earth radiates. But we can lose some small amounts of `H_2` as a result of disassociation of `H_2O` molecules in the atmosphere.

The mass of the `H_2` is just so tiny that Earth's gravity can sometimes struggle to hold onto it. But other than that, nothing natural tends to escape Earth, only an astronaut in his rocket!

NB: This is mainly a picture of Earth today, I welcome any additions relating to early Earth.