5. Why water is a good solvent for many different of solutes?

Question

6. Why should the solutes be added to water than water being added to solutes?

Answer 1

5. Because "like dissolves like". Water contains OH and it is as polar solvent so it can dissolve many covalent and many ionic substances.
6. Some solutes, an example is concentrated H2SO4, produces and extraordinarily high amount of heat which may cause the solvent to overheat, spatter, etc and possibly harm bystanders and/or the person doing the mixing.

Answer 2

Thanks DrBoB!