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Biomolecules appeared 36 times across 3 years — 4.2% of Chemistry. This question is from Carbohydrates.

Year 2026 2025 2024 Total
Questions 9 19 8 36

Given below are two statements: Statement I: Sucrose is dextrorotatory. However sucrose upon hydrolysis gives a solution having mixture of products. This solution shows laevorotation. Statement II: Hydrolysis of sucrose gives glucose and fructose. Since the laevorotation of glucose is more than the dextrorotation of fructose the resulting solution becomes laevorotatory. In the light of the above statements, choose the correct answer from the options given below.

Solution & Explanation

Related Formula
C₁₂H₂₂O₁₁ + H₂O H^+ D-Glucose + D-Fructose
Core Logic

Statement I: Pure sucrose has a specific rotation [α]D = +66.5°, so it is dextrorotatory. Upon hydrolysis, it forms an equimolar mixture of D-glucose and D-fructose. The net specific rotation of the mixture is negative, resulting in laevorotation. (This is called inversion of sugar). Statement I is true.

Statement II: Hydrolysis gives glucose and fructose. The specific rotation of D-glucose is +52.5° (dextrorotation), while that of D-fructose is -92.4° (laevorotation). The statement claims that glucose is laevorotatory and fructose is dextrorotatory, which is strictly backward. Therefore, Statement II is false.

Step 1: Final Conclusion

Statement I is true but Statement II is false.

Pattern Recognition

Invert sugar concepts are very common. Always verify which monomer rotates light in which direction. D-fructose is strongly laevorotatory (-92.4°).

Chapter Mix

Class 12 Chemistry: Biomolecules

Reference Study Guides

More Biomolecules Previous-Year Questions — Page 8

Q78 jee_main_2024_31_jan_morning Reactions of Glucose
Match List I with List II
LIST-ILIST-II
A. Glucose/NaHCO₃/ΔI. Gluconic acid
B. Glucose/HNO₃II. No reaction
C. Glucose/HI/ΔIII. n-hexane
D. Glucose/Bromine waterIV. Saccharic acid
Choose the correct answer from the options given below:
  • A. A-IV, B-I, C-III, D-II
  • B. A-II, B-IV, C-III, D-I
  • C. A-III, B-II, C-I, D-IV
  • D. A-I, B-IV, C-III, D-II

Solution

Core Logic

Matching the reactions of glucose: (A) Glucose does not react with NaHCO₃, so there is no reaction. (A arrow II) (B) Oxidation of glucose with strong oxidizing agents like HNO₃ yields a dicarboxylic acid called saccharic acid. (B arrow IV) (C) Prolonged heating of glucose with HI forms n-hexane, indicating a straight chain of six carbon atoms. (C arrow III) (D) Oxidation with mild agents like bromine water converts glucose to gluconic acid. (D arrow I)

Chapter Mix

Class 12 Chemistry: Biomolecules

More Biomolecules Questions — jee_main_2026_22_january_morning

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JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%) | JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%)