The answer is -- IT DEPENDS ON THE SUBSTANCE!
A "pound" is a measure of weight; a "gallon" is a measure of volume (space). The relationship of these two items is called "density." The denser the material, the less space it takes up for its weight.
Example: Lead is very dense, Styrofoam is not. A pound of lead will take up far less space (volume) than a pound of Styrofoam.
A "pound" is a measure of weight; a "gallon" is a measure of volume (space). The relationship of these two items is called "density." The denser the material, the less space it takes up for its weight.
Example: Lead is very dense, Styrofoam is not. A pound of lead will take up far less space (volume) than a pound of Styrofoam.