When starch is completely hydrolysed it yields (a) sucrose only (b) glucose only (c)glucose and fructose (d) glucose and maltose

When starch is completely hydrolyzed, it yields (b) glucose only.

Here's the step-by-step process:

1. Starch is a polysaccharide, which is a large molecule made up of many smaller monosaccharide molecules, specifically glucose.

2. Hydrolysis is a chemical reaction in which water is used to break down a compound. In the case of starch, hydrolysis breaks the glycosidic bonds between the glucose units.

3. The process of hydrolysis involves the addition of water molecules to the starch molecule. The water molecules break the bonds between the glucose units, resulting in individual glucose molecules.

4. Therefore, when starch is completely hydrolyzed, it yields glucose only.