4
Infinitely many.
A rectangular prism that is 4 cubes by 2 cubes is made up of 8 cubes.
8
24 of them
The answer depends on the number. Note that the question does not require the solids to be in the form of cubiods (rectangular prisms).
Some words that can be made from 'solids' are:Iidisdolidlossoiloldslidsosoilsold
13
4
You can make four.
Well, honey, if the height is 4 cubes, that leaves you with 12 cubes to work with for the base. You can arrange those 12 cubes in various ways to form different rectangular prisms. So, technically speaking, there are multiple rectangular prisms you can create with 48 cubes and a height of 4 cubes.
3
Infinitely many.
You could try 14!
A rectangular prism that is 4 cubes by 2 cubes is made up of 8 cubes.
8
about 10