NEET Chemistry Biomolecules / जैव-अणु Question Bank Self Evaluation Test - Biomolecules

  • question_answer
    Which of the following pairs can be distinguished by Fehling's solution?

    A) Glucose and fructose                   

    B) Glucose and sucrose

    C) Methanal and ethanol

    D) Hydroxypropanone and benzaldehyde.

    Correct Answer: B

    Solution :

    [b] Glucose is a hemiacetal, so in presence of a base (alkaline medium is provided by Fehling's solution) it can develop -CHO group in the form of open chain structure which responds Fehling's solution. Sucrose is a glycoside (acetal), i.e. its hemiacetal OH groups (one due to glucose and another due to fructose) are not free, so it can't attain -CHO group. Hence it will not respond Fehling's solution.


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