Separating Techniques; Filtration

You are provided with a mixture of sand and salt, which are to be separated. Follow the following procedure to separate these two solids getting a sample of sand at the end. Arrange the apparatus as shown in the diagram.

Distilled water is added to a mixture of salt and sand. The contents of the beaker are then stirred. A filter paper is folded first into two, and then into four so as to make a cone. The cone is placed in the filter funnel. The filter paper is then wetted with a little distilled water. The mixture of salt, sand and water are poured into the funnel. The beaker is washed with distilled water and the washings are poured into the funnel. Finally the recidue remaining on the filter paper are also washed with a little distilled water and allowed to dry. The sand could then be scrapped off from the surface of the paper and collected separately. The filtrate is saved for the following separating technique. 

Questions:

1.      Why was water added to the mixture of sand and salt?

2.      What was the purpose of the filter paper?

3.      What had happened to the salt on addition of water which made it possible for it to pass through the filter paper?

4.      Suppose you had two different solids, which are, both insoluble in water but one is soluble in the solvent toluene and the other one isn’t. Suggest a way of separating such two solids?

5.      So when you come to separate two solids, would you think of water as the only solvent you could use to effect a separation?