In the procedure for the synthesis of hexaphenylbenzene, a diels-alder reaction occurs and we needed to ensure all the starting materials were dry. after the reaction, we also washed with hexanes and toluene.
what is the purpose of this two things? also worth mentioning silicon oil was used as a solvent

nacl is added to the aqueous of what? ? in order to get a proper answer you have to specify the exact composition of the aqueous solution.

answer is: naturally occurring solid, inorganic compound or element is mineral.

minerals usually have crystalline form, that means than crystal constituents (atoms, molecules or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions.

for example magnetite is a mineral of iron oxide (fe₂o₃).

calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (caco₃).

dolomite is an   carbonate mineral composed of calcium magnesium carbonate (camg(co₃)₂).