Question

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R)
Assertion (A): Ketoses give Seliwanoff's test faster than Aldoses
Reason (R): Ketoses undergo -elimination followed by formation of furfural
In the light of the above statements, choose the correct answer from the options given below:

• A. Both (A) and (R) are true but $( R )$ is not the correct explanation of (A)
• B. (A) is false but (R) is true
• C. (A) is true but (R) is false
• D. Both (A) and (R) are true and (R) is the correct explanation of (A)

Hint:

When studying organic tests, remember the key principle behind each test. For example, Seliwanoff’s test differentiates between Ketoses and Aldoses based on the rate of dehydration to form furfural.

Answer 1

The Correct Option is C

The question involves understanding the behavior of ketoses and aldoses in Seliwanoff's test, which is a chemical test to distinguish between these two types of sugars.

• Assertion (A): Ketoses give Seliwanoff's test faster than Aldoses.
• Reason (R): Ketoses undergo 𝛽-elimination followed by formation of furfural.

To evaluate the statements, let's understand some chemistry concepts:

1. Seliwanoff's Test:
   • This is a qualitative test used to differentiate between aldoses and ketoses. The reagent used is resorcinol in hydrochloric acid.
   • Ketoses react faster than aldoses in this test because they form furfural derivatives more quickly upon heating with acid. This is due to their structure, which facilitates quicker dehydration.
2. Explanation of Assertion and Reason:
   • Assertion (A) is true because ketoses indeed react faster in Seliwanoff's test as compared to aldoses due to their structural configuration which allows for rapid dehydration.
   • However, Reason (R) mentions "𝛽-elimination followed by formation of furfural", which is not an accurate explanation of the process involved. The reaction sequence involves dehydration to form furfural but not through a 𝛽-elimination pathway.
3. Conclusion:
   • Thus, while both statements appear related to the chemical reaction context, the specific mechanism described by the reason is incorrect.

Therefore, the correct choice is: (A) is true but (R) is false.