Question

Assertion: Glucose does not give 2,4-DNP test.
Reason: Glucose exists in cyclic hemiacetal form.

• A. Both assertion and reason are true but reason is not the correct explanation of assertion.
• B. Both assertion and reason are true and reason is the correct explanation of assertion.
• C. Assertion is true but reason is false.
• D. Both assertion and reason are false.

Answer 1

The correct option is B Both assertion and reason are true and reason is the correct explanation of assertion.

2,4-Dinitrophenylhydrazine can be used for the qualitative identification of ketone or aldehyde functional group carbonyl functionality. A positive test is indicated by the formation of a precipitate known as dinitrophenylhydrazone, yellow, orange, or red.
As the glucose exists in cyclic hemiacetal form, this indicates that the aldehydic group in glucose is not free and hence it does not give 2,4-DNP test.