generally the solute
Because the particles of hydrogen in the water are charged
Yes. Its polarity allows it to dissolve other polar substances and many ionic compounds.
No, the sugar is the solute and the water is the solvent.
sometimes. All solutions have at least one solute and one solvent. While water often does act as a solvent, some solutions have other solvents. Solutions where the solute is dissolved in water belong to a special group of solutions called aqueous solutions.
The question doesn't make any sense. All gases are miscible, so any other gas could act as either a solute or solvent of gaseous nitrogen.
Hydrogen chloride is a polar compound. Therefore it can act as a solvent to particular polar compounds.
The more surface area of a solute is exposed to a solvent, the more quickly the solvent can act on the solute, dissociating it if it's ionic. This is why finely grained salt dissolves much more quickly than a large clump of salt.
A solution can have many definitions. It would mean the act of solving a problem or the state of being solved or the process of determining an answer to a problem. You can find definitions like these on dictionary.com
Pour an ionic solid into water and see if it vanishes. (Because it has the ability to dissolve.)
Probably in ionic compounds where they act as anions. I don't think OBr2 will exist everywhere at all.
For a given temperature and solvent, the solubility of a substance is fixed, but the rate at which a ground substance is disolved is greater because the fine particles present a greater surface area upon which the solvent can act.
The electronegativity difference between oxygen and hydrogen is quite large, which means that bond possess a high polarity. This enables water (which has two O-H bonds) to "surround" similar covalent compounds and dissociate many ionic compounds.