QJEEM25Chbb48: JEE Main 2025 Chemistry - Class 12 JEEM25Chbb48 Solution: Given below are two statements: Statement I : D-glucose…
Given below are two statements:
Statement I : D-glucose pentaacetate reacts with 2,4 -dinitrophenylhydrazine
Statement II : Starch, on heating with concentrated sulfuric acid at and pressure produces glucose.
In the light of the above statements, choose the correct answer from the options given below
Multiple Choice Options
- A Statement I is true but Statement II is false
- B Both Statement I and Statement II are true
- C Statement I is false but Statement II is true
- D Both Statement I and Statement II are false
Step-by-Step Verified Solution
Statement I: D-glucose pentaacetate does not react with 2,4-dinitrophenylhydrazine (DNPH). This is because D-glucose pentaacetate is a derivative where all the hydroxyl groups of D-glucose have been acetylated, eliminating the presence of a free aldehyde group. Since DNPH reacts specifically with free aldehyde or ketone groups to form hydrazones, D-glucose pentaacetate does not participate in this reaction.
Statement II: Starch, when heated with concentrated sulfuric acid at 100°C and under a pressure of 2-3 atmospheres, undergoes hydrolysis. This process breaks the glycosidic linkages in starch, resulting in the production of glucose. This statement is accurate as starch is a polysaccharide composed of glucose units and can be broken down into glucose under these conditions.
The correct information based on the statements is:
Statement I is false, as D-glucose pentaacetate does not react with 2,4-dinitrophenylhydrazine due to the absence of a free aldehyde group.
Statement II is true, as the described method effectively converts starch into glucose.