As the volume increases on a object what happens to the mass of each sample

How much heat is released upon converting one mole of steam (18.0 g) from 100.0 ∘c to water at 25.0 ∘c? show work and constants, trying to figure out how it works. only given the heat capacity for steam and water so try to only use that

How to convert a density of 0.791g/cm3 to lb/ft3

What type of matter is made of only one kind of atom