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Question #44008
The Question
A mixture contains each of the following five carbohydrates: (I) D-Fructose (II) Sucrose (III) Cellobiose (IV) 2,3,4,6-tetra-O-methyl-D-glucopyranose (V) Methyl -D-galactopyranoside
The mixture is dissolved in an aqueous buffer at and treated with an excess of Tollens' reagent () at until no further reaction occurs. Assuming quantitative conversion for all reactive species, what is the total mass of silver deposited? (Molar mass of )
Options
- A.
162 g
- B.
108 g
- C.
54 g
- D.
216 g
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Exception_Exposure
Learn to identify edge cases and boundary exceptions that JEE examiners hide in math problems.
Concepts Behind This Question
Tollens vs. Fehling Specificity|Reducing Sugar Criteria|D-Glucose Anomeric Equilibrium
Why This Question Is Tricky
Common Mistakes
This problem tests the fundamental criteria for reducing sugars and the dynamic equilibrium (mutarotation) required for Tollens' oxidation.
The primary trap is structural: students often misclassify 2,3,4,6-tetra-O-methyl-D-glucopyranose as a non-reducing acetal due to the heavy methylation, failing to recognize that the C1 position remains a free hemiacetal capable of ring-opening.
A secondary trap involves D-Fructose; students must recall that basic conditions (inherent to Tollens' reagent) trigger the Lobry de Bruyn-van Ekenstein rearrangement, converting the ketose into oxidizable aldoses.
Finally, it tests the stability of acetals (Sucrose, Methyl beta-D-galactopyranoside) in basic media, ensuring students don't incorrectly assume hydrolysis occurs.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Aldehydes, Ketones, and Carboxylic Acids - Class 12 |
| Concept | Tollens vs. Fehling Specificity |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |