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Correct Answer: B
Correct Answer: B
Method / Topic: Organic Chemistry
The correct option matches the required rule and the given information.
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Correct Answer: B
Method / Topic: Organic Chemistry
Both aldehydes and ketones usually react with 2,4-DNP and both can be reduced to alcohols. Tollens reagent generally oxidizes aldehydes and produces a silver mirror, while ordinary ketones give a negative result. Therefore the negative Tollens test is the most discriminating observation. This conclusion follows from electron flow, functional-group behavior, and the stated experimental conditions. For MCAT organic chemistry, first mark the nucleophile, electrophile, leaving group, and any resonance-stabilized intermediate; then track bonds rather than memorizing a product name. Check stereochemistry, charge, and carbon count before choosing an
, and interpret evidence without overclaiming. Always reconcile the proposed structure with every observation in the
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PASSAGE 3 — IDENTIFYING AN UNKNOWN CARBONYL COMPOUND An unknown liquid has molecular formula C4H8O. Its IR spectrum contains a strong absorption near 1715 cm−1 but no broad O–H band. Its proton NMR spectrum shows three signals: a 3 H triplet, a 2 H quartet, and a 3 H singlet. The compound gives a positive 2,4-DNP test and a negative Tollens test. On reduction with sodium borohydride, it forms an alcohol. QUESTION 8: Which observation most specifically distinguishes the unknown ketone from an aldehyde?
Explanation
Correct Answer: B
Method / Topic: Organic Chemistry
The correct option matches the required rule and the given information.
Short Explanation
Detailed Explanation
Correct Answer: B
Method / Topic: Organic Chemistry
Both aldehydes and ketones usually react with 2,4-DNP and both can be reduced to alcohols. Tollens reagent generally oxidizes aldehydes and produces a silver mirror, while ordinary ketones give a negative result. Therefore the negative Tollens test is the most discriminating observation. This conclusion follows from electron flow, functional-group behavior, and the stated experimental conditions. For MCAT organic chemistry, first mark the nucleophile, electrophile, leaving group, and any resonance-stabilized intermediate; then track bonds rather than memorizing a product name. Check stereochemistry, charge, and carbon count before choosing an
, and interpret evidence without overclaiming. Always reconcile the proposed structure with every observation in the
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