Concept:Step II supplies an acidic medium needed to hydrolyse non-reducing sugars into reducing sugars before Benedict’s test.
Explanation:Non-reducing sugars, like sucrose, cannot reduce Benedict’s solution directly.
They must first be broken down into reducing sugars such as glucose and fructose.
In step II, dilute
HCl is added and the mixture is boiled.
The acid provides the required acidic condition for hydrolysis to occur.
This hydrolysis breaks the glycosidic bond in sucrose and produces reducing sugars.
Step III then adds sodium hydroxide to neutralise the acid, because Benedict’s solution works properly in an alkaline medium.
Finally, in step IV, Benedict’s solution is added to the cooled solution to confirm the presence of the reducing sugars formed.
Therefore, step II is important because it increases the acid content of the sugar solution, enabling acid hydrolysis to take place.
Answer:D — to increase the acid content of the sugar solution so that hydrolysis can occur.