Squeeze it.
Weight. (Since fluid is squeezed out, the compressed sponge weighs less). However, if the question refers to compressing a dry sponge, then the only quantity that would change would be volume.
dry
It depends on the mass of the sponge.
Leave the sponge out in open air for a day or so. It should dry just fine on its own. If you're in a major hurry to dry it, you could dry using a blow-dryer.
Measuring the mass of sponge iron.
Solution
To answer this we need also the density of the sponge material.
He has a fear of dry sponge.
no; they have the same volume but their mass is quite different; density is mass/volume and the sponge has much lower density
Evaporation
less than a minute