Which rock having specific gravity lower than water & sponge like?

Solution (By Examveda Team)

Pumice is a rock having a specific gravity lower than water and sponge.
Specific gravity refers to the ratio of a solid or liquid to the density of water at 4 degrees Celcius.
Pumice is a pyroclastic igneous rock. It is extremely porous, with a foamy appearance. The specific gravity of pumice is found to be 0.95.