AIIMS 2019 Biology Carbohydrates MCQ Question

Polysaccharides can be tested using iodine, which forms a blue-black complex with starch, a common polysaccharide, due to the helical structure of amylose. This reaction is specific to polysaccharides, making iodine a reliable indicator. In contrast, HCl (option B) is a strong acid that can hydrolyze polysaccharides but does not provide a specific test, while KCl (option C) and KNO₃ (option D) are salts that do not react with polysaccharides in a way that indicates their presence. Thus, iodine is the most suitable reagent for detecting polysaccharides.