Question

using the molecule depicted here, which of the following tests should yield a positive result. biurets test bromine test iodine test barfoeds test

Explanation:

The molecule shown is a polysaccharide (long chain of sugar units). Barfoed's test is used to detect monosaccharides (reducing sugars), but polysaccharides can be hydrolyzed to monosaccharides or may have reducing ends. Wait, actually, let's re - evaluate: The structure has multiple sugar units linked (glycosidic bonds), typical of a polysaccharide. But Barfoed's test is for reducing sugars (monosaccharides). Wait, no, maybe I made a mistake. Wait, the options: Biuret's test is for proteins, Iodine test is for starch (a polysaccharide), Bromine test (maybe for unsaturation, not relevant here), Iodine test detects starch (polysaccharide) by blue - black color. Wait, the structure looks like a polysaccharide (e.g., starch or glycogen - like with multiple glucose units). So Iodine test: iodine reacts with polysaccharides (starch) to give a blue - black color. Biuret's test is for peptide bonds (proteins), Bromine test is for alkenes (unsaturated bonds), Barfoed's is for monosaccharides. So the correct test for a polysaccharide (if it's starch - like) is Iodine test? Wait, no, wait the structure: looking at the molecule, it's a long chain of sugar molecules (each with a hexose ring, hydroxyl groups, glycosidic linkages). So it's a polysaccharide. Iodine test (Iodine in KI) forms a charge - transfer complex with the helical structure of amylose (a polysaccharide), giving a blue - black color. So the Iodine test should give a positive result. Wait, but let's check the options again. The options are Biuret's (protein), Bromine (unsaturation), Iodine (starch/polysaccharide), Barfoed's (monosaccharides). So the molecule is a polysaccharide, so Iodine test is for polysaccharides (starch - type). So the correct answer is Iodine test? Wait, no, maybe I messed up. Wait, Barfoed's test: is for reducing sugars, but polysaccharides can be non - reducing or reducing. Wait, the structure: each sugar unit has a hemiacetal? No, in polysaccharides, the reducing end may be present or not. But the Iodine test is specific for polysaccharides (starch) which have a helical structure. So the Iodine test (option B: Iodine test) should be the one that gives a positive result for this polysaccharide.

Answer:

Iodine test (the option with "Iodine test" as the text, assuming the option identifier for Iodine test is the one labeled "Iodine test" in the list)