Why starch(a well known carbohydrate) is not soluble in cold water although sugar(carbohydrate) is ?

Starch is a more complex form of Sugar. When we generally speak sugar, we mean disaccharides. A chemist will define Glucose, fructose and many more things as Sugar. Starch is a natural polymer made up of many type of beta-glucose subunits. As it is a general rule in chemistry higher the molecular weight / or / longer the chain / or more crossed structure - solubility will be less. Most Monosaccharrides, disaccharrides and trisaccharides are soluble in water, longer chain sugars such as starch are much less soluble, especially in cold water, and better soluble in hot water.