Mass of CO₂ and H₂O remaining in the mantles of different mass planets after the solidification of the magma ocean. It is evident that low mass planets tend to outgas water much more efficiently than high mass planets. While the variation in outgassed CO₂ is not as large as for H₂O, due to the lower solubility of CO₂ in magma, the tendency for high-mass planets to retain a larger mantle volatile reservoir extends to CO₂ as well.