Human fat has a density of 0.918 g/cm3. how much volume (in cm3) is gained by a person who gains 10.5 lb of pure fat?

The density of a substance is the constant ratio of its mass to its volume at a certain temperature and pressure condition. For solids, the density is not that sensitive to changes in temperature and pressure. Hence, we use the density and mass to calculate the corresponding volume. The conversion needed is 2.2 lb = 1,000 grams.

Density = Mass/Volume
Volume = Mass/Density
Volume = 10.5 lb(1,000 g/2.2 lbs)/0.918 g/cm³
Volume = 5,199 cm³

Most smaller stars don't have a radiative zone.