Cellobiose is a complex carbohydrate which consists of two molecules of glucose that are combined by a β–(1,4′) glycosidic bond.
Cellobiose is a polar compound just like every other carbohydrate.
Polar compound are those compounds that usually have an end with a positive charge and another with a negative charge.
When cellobiose just like every other glucose is dissolve in water or any other polar solvent, it completely dissolves in the solution. Examples of polar solvents are ethanol, water etc.
Cellobiose is a polar compound just like it's parent compound glucose.