Acid-catalyzed hydrolysis of sucrose

Steps:

• Identify the reaction as inversion of sucrose, where acid breaks the glycosidic bond.
• Note H+ ions serve as the catalyst to facilitate hydrolysis.
• Recognize sucrose as the disaccharide reactant providing glucose and fructose units.
• Confirm labels X and Y correspond to catalyst and substrate, respectively.

Why A is correct:

• In sucrose hydrolysis, H+ ions catalyze the reaction of sucrose (C12H22O11 + H2O → C6H12O6 + C6H12O6), matching X as H+ and Y as sucrose per the chemical equation.

Why the others are wrong:

• B: Glucose is a product, not the initial substrate Y.
• C: Glucose is a product, not the initial substrate Y.
• D: Reverses the labels; H+ is catalyst (X), not product (Y).

Final answer: A