Which among the following reduces Fehling’s solution?
1
Acetic acid
2
Formic acid
3
Benzoic acid
4
Salicylic acid
Official Solution
Correct Option:
(2)
Step 1: Fehling’s solution reaction. Fehling’s solution is a mixture of copper sulfate and alkali used to test for aldehydes. Formic acid (a form of aldehyde) reduces Fehling’s solution, while other acids do not. Step 2: Conclusion. Thus, formic acid reduces Fehling’s solution.
02
PYQ 2006
medium
chemistryID: viteee-2
What is the reaction of acetaldehyde with concentrated sulphuric acid?
1
No reaction
2
Decomposition
3
Charred to black residue
4
Polymerisation
Official Solution
Correct Option:
(3)
Step 1: Understand the reaction with concentrated H SO . Acetaldehyde, when reacted with concentrated sulfuric acid, undergoes dehydration and polymerization, ultimately forming a black residue. Step 2: Conclusion. Thus, acetaldehyde is charred to a black residue when treated with concentrated sulfuric acid.
03
PYQ 2007
medium
chemistryID: viteee-2
The catalyst used in Rosenmund reaction is
1
Zn / Hg
2
Pd / BaSO₄
3
Raney Ni
4
Na in Ethanol
Official Solution
Correct Option:
(2)
Step 1: Understanding Rosenmund reaction. In the Rosenmund reduction, an acyl chloride is reduced to an aldehyde using palladium on barium sulfate (Pd / BaSO₄) as a catalyst.
Step 2: Conclusion. Thus, the correct catalyst is option (B).
Final Answer:
04
PYQ 2007
medium
chemistryID: viteee-2
C₆H₅CHO + NH₃ ?
1
C₆H₅NH₂
2
C₆H₅NHC₆H₅
3
C₆H₅CH₂NH₂
4
C₆H₅NH₃
Official Solution
Correct Option:
(3)
Step 1: Hydrogenation reaction. When aromatic aldehydes like benzaldehyde react with ammonia in the presence of hydrogen and nickel, they undergo reduction to form the corresponding amine. In this case, the product formed is phenylethylamine.
Step 2: Conclusion. Thus, the correct product is phenylethylamine , so the correct answer is option (C).
Final Answer:
05
PYQ 2011
medium
chemistryID: viteee-2
Which of the following will give Cannizzaro reaction?
1
A
2
B
3
C
4
D
Official Solution
Correct Option:
(3)
Step 1: Understand Cannizzaro reaction. The Cannizzaro reaction involves the base-induced disproportionation of non-enolizable aldehydes, which results in the formation of an alcohol and an acid. Step 2: Conclusion. The aldehyde undergoes the Cannizzaro reaction. Final Answer:
06
PYQ 2014
medium
chemistryID: viteee-2
What will be the order of reactivity of the following carbonyl compounds with Grignard’s reagent?
1
2
3
4
Official Solution
Correct Option:
(1)
The reactivity of carbonyl compounds with Grignard’s reagent depends on the steric and electronic factors. Compound I is more reactive due to the less hindered carbonyl group.
07
PYQ 2014
medium
chemistryID: viteee-2
Which of the following pairs give positive Tollen’s test?
1
Glucose, sucrose
2
Glucose, fructose
3
Hexanal, acetophenone
4
Fructose, sucrose
Official Solution
Correct Option:
(2)
Tollen's test is positive for aldehydes and reducing sugars. Glucose and fructose are reducing sugars, so they will give a positive result.
08
PYQ 2016
medium
chemistryID: viteee-2
Acetophenone and Benzophenone can be distinguished by which of the following test
1
Knoevenagel reaction
2
Canizzaro’s reaction
3
Aldol condensation
4
HVZ Reaction
Official Solution
Correct Option:
(2)
Step 1: Understanding the Reaction.
Acetophenone and benzophenone can be distinguished by the Canizzaro’s reaction, where aldehydes without an alpha-hydrogen undergo disproportionation to form an alcohol and an acid. Step 2: Conclusion.
The correct answer is (B), Canizzaro’s reaction.
09
PYQ 2016
medium
chemistryID: viteee-2
By which reaction ketal is formed?
1
Glycol with acetone
2
Hydration of glycol
3
Condensation of glycol
4
Glycol with acetaldehyde
Official Solution
Correct Option:
(1)
Step 1: Ketal Formation.
Ketal formation occurs when a glycol reacts with an aldehyde or ketone. The reaction between glycol and acetone forms a ketal. Step 2: Conclusion.
The correct answer is (A), Glycol with acetone.
10
PYQ 2017
medium
chemistryID: viteee-2
A mixture of benzaldehyde and formaldehyde on heating with aqueous NaOH solution gives
1
sodium benzoate and sodium formate
2
sodium benzoate and methyl alcohol
3
benzyl alcohol and methyl alcohol
4
benzyl alcohol and sodium formate
Official Solution
Correct Option:
(1)
Step 1: Understand the reaction.
When benzaldehyde and formaldehyde are heated with aqueous NaOH, they undergo the benzoin condensation, forming sodium benzoate and sodium formate. Step 2: Conclusion.
Thus, the products are sodium benzoate and sodium formate. Final Answer:
11
PYQ 2017
medium
chemistryID: viteee-2
The number of aldol reaction(s) that occurs in the given transformation is:
1
1
2
2
3
3
4
4
Official Solution
Correct Option:
(3)
Step 1: Understand the aldol condensation.
Aldol reaction is the condensation between two carbonyl compounds. The reaction given shows the condensation of 5 molecules of acetaldehyde. Step 2: Conclusion.
Thus, the number of aldol reactions is 3. Final Answer:
12
PYQ 2017
medium
chemistryID: viteee-2
Which of the following is not intermediate in the acid catalysed reaction of benzaldehyde with 2 equivalent of methanol to give acetal?
1
A
2
B
3
C
4
D
Official Solution
Correct Option:
(3)
Step 1: Understand the reaction mechanism.
In the reaction of benzaldehyde with methanol, the intermediate is formed by protonation and nucleophilic attack, but is not an intermediate in this reaction. Step 2: Conclusion.
Thus, the intermediate that is not involved is . Final Answer:
13
PYQ 2018
medium
chemistryID: viteee-2
The reagent(s) which can be used to distinguish acetophenone from benzophenone is (are):
1
2,4-dinitrophenylhydrazine
2
aqueous solution of NaHSO₃
3
Benedict reagent
4
I and Na₂CO₃
Official Solution
Correct Option:
(1)
Step 1: 2,4-Dinitrophenylhydrazine reacts with carbonyl compounds to form hydrazones. This reagent can distinguish acetophenone from benzophenone. Step 2: Acetophenone reacts to form a hydrazone, whereas benzophenone does not.
Final Answer:
14
PYQ 2019
medium
chemistryID: viteee-2
An organic compound 'A' has the molecular formula , it undergoes iodoform test. When saturated with dil. HCl it gives 'B' of molecular formula . A and B respectively are:
1
Propanal and mesitylene
2
Propanone and mesityl oxide
3
Propanone and 2,6-dimethyl-2,5-heptadien-4-one
4
Propanone and mesitylene oxide
Official Solution
Correct Option:
(2)
The compound A reacts with iodoform reagent to give a yellow precipitate, confirming the presence of a methyl ketone group. Propanone undergoes this reaction to form mesityl oxide. Final Answer:
15
PYQ 2019
medium
chemistryID: viteee-2
Tautomerism is net exhibited by:
1
A
2
B
3
C
4
D
Official Solution
Correct Option:
(1)
Tautomerism is a form of isomerism where two isomers can interconvert through the transfer of a proton or rearrangement of electrons, typically in compounds with a keto-enol type relationship. Final Answer:
About Aldehydes And Ketones - VITEEE
Aldehydes And Ketones is a vital chapter for VITEEE aspirants. Mastering the concepts covered in this chapter is essential for securing a top rank.
By rigorously practicing the previous year questions associated with this chapter, you can identify high-yield topics, understand the examiner's perspective, and boost your confidence during the actual exam.
Frequently Asked Questions
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Analyzing PYQs for this specific chapter reveals the most frequently tested concepts and the typical complexity of questions, allowing you to tailor your study plan efficiently.
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Review the topic breakdown to see which sub-topics within Aldehydes And Ketones carry the most weight. Then, tackle the questions iteratively to solidify your understanding.
