Consider equal volumes (say 1 l of a given substance in the solid, liquid, and gas phases. arrange them in order of decreasing mass based on the trend for the average substance. if the mass difference between samples is relatively small (10% or less, rank the items as equivalent.

In the common cases, solids have all the particles close together and held in place, liquids have the particles close together (less than solids) but not held, and gases have the particles more separated than the previous cases.

So, in a defined volume, usually, solids will have more mass, this is because particles are close together and you can put more particles in a given volume, then comes liquid, and the comes to gas.

An exception of this can be water, where the solid-state is less dense than the liquid state (this is why ice floats in liquid water)

Here for a fixed volume, liquid water has more mass than the solid-state, and the solid-state has more mass than the gas state.