80Nm I'm pretty sure this is the answer if I'm wrong I'm sorry but I'm positive it the answer
Answer:
I know that Aerogel is the lightest metal in existence, but I don't think it would help much with your answer. I mean you can give it a try?
Barrier islands typically have sand in the beach zone and dune field, and mud in the back-barrier. Overwash deposits sand in the back-barrier.
Barrier islands form in three ways. They can form from spits, from drowned dune ridges or from sand bars. Longshore drift is the movement of sand parallel to the shore caused by the angle of the waves breaking on the beach. ... When a storm such as a hurricane digs an inlet through the spit a barrier island is formed.
Salt hydrates are an important class of PCMs. An inorganic salt hydrate (hydrated salt or hydrate) is an ionic compound in which the ions attract a number of water molecules, which are then trapped inside the crystal lattice. A hydrated salt has the generic formula MxNy. nH2O.