NEET Chemistry: Aldol condensation Cannizzaro reaction and Chemical tests for differentiation Practice Questions
11 free multiple-choice questions on Aldol condensation Cannizzaro reaction and Chemical tests for differentiation (Aldehydes and Ketones) for NEET Chemistry, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.
Practice thousands more NEET questions in the app →Q1. Which of the following reactions is a key step in the synthesis of β-hydroxy carbonyl compounds from aldehydes?
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Correct answer: A — Aldol condensation
Aldol condensation is the reaction where an enolate attacks another carbonyl group, forming β-hydroxy carbonyl compounds, which is a primary reaction involving aldehydes and ketones.
Q2. Which reagent is commonly used to distinguish between an aldehyde and a ketone based on their reactivity with haloform reagents?
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Correct answer: C — NaHSO₃
Sodium hypothiocyanate (NaHSO₃) test (or haloform test derivatives) is often used in introductory organic chemistry to probe the difference in oxidation states and reactivity between aldehydes and ketones, although specific differentiation tests are more common.
Q3. In the Aldol condensation reaction, the reaction is usually base-catalyzed. What is the primary role of the base in this reaction?
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Correct answer: A — To facilitate enolization and subsequent nucleophilic attack
The base removes an α-hydrogen from the carbonyl compound to form an enolate ion, which then acts as a nucleophile to attack another carbonyl group.
Q4. Which chemical test is commonly used to distinguish between an aldehyde and a ketone based on their reaction with Fehling's solution?
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Correct answer: A — Fehling's test
Fehling's test is a qualitative test used to distinguish between aldehydes (which reduce Fehling's solution) and ketones (which do not reduce it).
Q5. Which one of the following reagents is generally used to convert an aldehyde into a carboxylic acid under basic conditions, leading to aldol condensation products?
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Correct answer: C — Sodium hydroxide (NaOH)
Sodium hydroxide (or an alcoholic solution of NaOH) is a strong base used to catalyze the aldol condensation reaction between aldehydes and ketones, often forming β-hydroxy carbonyl compounds.
Q6. The Cannizzaro reaction is a disproportionation reaction specific to which type of carbonyl compound?
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Correct answer: D — Aliphatic aldehydes
The Cannizzaro reaction occurs exclusively for aldehydes that do not have α-hydrogens (like Benzaldehyde) or for aldehydes lacking α-hydrogens (like Formaldehyde).
Q7. Which of the following compounds primarily undergoes the Aldol condensation reaction when treated with a strong base?
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Correct answer: C — Both Aldehydes and Ketones
Aldol condensation requires the presence of both an aldehyde or ketone group and an α-hydrogen. Both aldehydes and ketones can participate, leading to aldol products.
Q8. Which of the following compounds will not participate in the Aldol condensation reaction readily under typical conditions?
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Correct answer: B — Butanal
While all listed compounds can theoretically participate, the extent of self-condensation depends on the structure and conditions. Propanal (an aldehyde) undergoes self-condensation more readily than the others in a typical context compared to other structures.
Q9. The reaction that results in the formation of a carboxylic acid upon treatment of an aldehyde with an excess of a strong base is known as:
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Correct answer: C — Cannizzaro reaction
The Cannizzaro reaction involves the disproportionation of an aldehyde to form a carboxylic acid and an alcohol when treated with an excess of a strong base.
Q10. The Cannizzaro reaction is characteristic of which type of carbonyl compounds?
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Correct answer: C — Aromatic aldehydes
The Cannizzaro reaction occurs exclusively for aldehydes lacking α-hydrogen, typically in the presence of a strong base. Ketones do not undergo this disproportionation reaction.
Q11. Which chemical test is used to distinguish between an aldehyde and a ketone based on their reactivity with aqueous solutions of alkali metals?
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Correct answer: A — Fehling's test
Fehling's test (using Cu(OH)₂ solution) differentiates aldehydes from ketones, as aldehydes reduce the solution, whereas ketones generally do not react.
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