Carbon dioxide and helium which has a higher van der waals force of attraction between molecules

Carbon dioxide  

Explanation:

Neither helium nor carbon dioxide has a molecular dipole, so their strongest van der Waals attractive forces are London forces.

Helium is a small spherical atom with only a two electrons, so its atoms have quite weak attractions to each other.

CO₂ is a large linear molecule. It has more electrons than helium, so the attractive forces are greater. Furthermore, the molecules can align themselves compactly side-by-side and maximize the attractions (see below).

For example. CO₂ becomes a solid at -78 °C, but helium must be cooled to -272 °C to make it freeze (that's just 1 °C above absolute zero).

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> they are both natural and not man made

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