Which of the following carbohydrates is formed when aqueous decomposition of starch is done?

The correct answer is Glucose.

Key Points

Concept:

• Starch is a polysaccharide that occurs in plants in the form of granules which are found mainly in seeds, fruits, tubers, and roots of plants.
• It is a mixture of two polysaccharides amylose 20% and amylopectin 80%.
• Amylose is water-soluble while amylopectin is insoluble.
• Both amylose and amylopectin are polymers of glucose.
• Amylose is composed of 60 -300 glucose units linked together to form unbranched chains.
• On the other hand, amylopectin is a branched-chain polysaccharide made up of about 1000 glucose units.
• The structures of amylose and amylopectin are given which are composed of glucose units

Explanation:
Hydrolysis of starch:

• On hydrolysis with hot dilute acids, starch yields a syrupy mixture of glucose maltose and high molecular weight saccharides.
• It changes to dextrin at temperatures between 200 - 250 ⁰C.
• The digestive enzymes in humans convert starch ultimately to glucose which is the source of energy.
• The reaction scheme is:

Hence, Glucose is formed when the aqueous decomposition of starch is done.
Additional Information

• Starch is a white amorphous solid having no definite melting point. It has no taste or smell.
• It is insoluble in water.
• Starch gives a blue colour with a drop of iodine solution.
• Starch doesn't reduce Tollen's or Fehling's solution.