Sugar dissolving in hot tea is an example of which characteristic property?

It's solubility. Solubility is a measure of the ability of a solute to dissolve in a solvent; maximum amount of solute that will dissolve in solvent at a specific temperature. Solute is substance being dissolved. Solvent is the substance that is doing the dissolving; the part of the solution that is present in the greatest quantity.

It's solubility because that's the only characteristic that's either gone in a drink or melted

Answer(a)   the matererials that are in contact, the two materials and the nature of their surfaces/// (b)/// the force pushing the two surfaces together, pushing the surfaces together causes the more of the asperities to come together and increases the surface area in contact with each other