Aldehydes, Ketones and Carboxylic Acids Chapter-Wise Test 13

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which reaction sequence converts pentan-2-one to 2-methylpentane?

Step 1: \( \ce{NaBH4} \) reduces pentan-2-one (\( \ce{CH3COCH2CH2CH3} \)) to pentan-2-ol (\( \ce{CH3CH(OH)CH2CH2CH3} \)). Step 2: Clemmensen reduction (or dehydration + hydrogenation) yields 2-methylpentane (\( \ce{CH3CH(CH3)CH2CH2CH3} \)), but Wolff-Kishner fits PDF scope directly.

\( \ce{LiAlH4} \) then \( \ce{PCC} \)
\( \ce{KMnO4} \) then \( \ce{NaBH4} \)
\( \ce{H2, Pd} \) then \( \ce{SOCl2} \)
\( \ce{NH2NH2, KOH} \)
4

Which test produces a brick-red precipitate with propanal but not with propanone?

Fehling’s test oxidizes aldehydes like propanal (\( \ce{CH3CH2CHO} \)) to carboxylic acids, forming a brick-red \( \ce{Cu2O} \) precipitate, but does not react with ketones like propanone.

Iodoform test
Fehling’s test
2,4-DNP test
Tollens' test
2

What is the product when cyclohexanecarbaldehyde reacts with \( \ce{PhMgBr} \) followed by hydrolysis?

Cyclohexanecarbaldehyde (\( \ce{C6H11CHO} \)) reacts with phenylmagnesium bromide (\( \ce{PhMgBr} \)), a Grignard reagent, adding a phenyl group to the carbonyl carbon. Hydrolysis yields \( \ce{C6H11CH(OH)Ph} \), a secondary alcohol.

Cyclohexylmethanol
Cyclohexylphenylmethanol
Phenylcyclohexane
Cyclohexanone
2

What is the product when butanal reacts with \( \ce{NaBH4} \)?

\( \ce{NaBH4} \) reduces aldehydes to primary alcohols. Butanal (\( \ce{CH3CH2CH2CHO} \)) forms butan-1-ol (\( \ce{CH3CH2CH2CH2OH} \)).

Butane
Butan-2-ol
Butan-1-ol
Butanoic acid
3

Which reagent can oxidize an aldehyde to a carboxylic acid?

Tollens' reagent (ammoniacal silver nitrate) is a mild oxidizing agent that converts aldehydes to carboxylic acids, forming a silver mirror as a byproduct.

Tollens' reagent
Zn amalgam with HCl
LiAlH₄
NaBH₄
1

What is the product of the Clemmensen reduction of pentan-2-one?

Clemmensen reduction (\( \ce{Zn(Hg), HCl} \)) converts ketones to hydrocarbons. Pentan-2-one (\( \ce{CH3COCH2CH2CH3} \)) yields pentane (\( \ce{CH3CH2CH2CH2CH3} \)).

Pentan-2-ol
Pentane
Pentanal
Pent-2-ene
2

Which compound forms a cyclic acetal when treated with ethylene glycol?

Cyclohexanone (\( \ce{C6H10O} \)), a ketone, reacts with ethylene glycol (\( \ce{HO-CH2CH2-OH} \)) under acidic conditions to form a cyclic acetal, protecting the carbonyl group.

Cyclohexanone
Cyclohexanol
Benzoic acid
Phenol
1

Which test distinguishes propanal from propanone?

Fehling’s solution oxidizes aldehydes (like propanal) to carboxylic acids, forming a red precipitate, but does not react with ketones (like propanone).

Iodoform test
2,4-DNP test
Fehling’s test
Schiff’s test
3

What is the common name of \( \ce{C6H5COOH} \)?

The compound \( \ce{C6H5COOH} \) (benzoic acid in IUPAC) is historically known as benzoic acid in common nomenclature as well.

Phenylacetic acid
Benzoic acid
Toluic acid
Formic acid
2

Which compound gives a positive Tollens' test and a negative Fehling’s test?

Benzaldehyde (\( \ce{C6H5CHO} \)) is an aromatic aldehyde (positive Tollens' test) but does not reduce Fehling’s solution due to lower reactivity.

Benzaldehyde
Ethanal
Propanal
Acetone
1

Performance Summary

Score:

Category Details
Total Attempts:
Total Skipped:
Total Wrong Answers:
Total Correct Answers:
Time Taken:
Average Time Taken per Question:
Accuracy:
0