How many gallons are in eighteen pounds?

Answer 1

It depends upon the substance of the18 lb.

Weight and volume are linked by density:

density = weight/volume → volume = weight / density.

18 lb of Mercury occupies a much smaller volume than 18 lb of hydrogen.

Answer 2

That will depend on a gallon of WHAT. Gallon is a measure of volume, pounds are a measure of weight. They do not interchange. A gallon of water weighs more than a gallon of oil.