Aldehydes, Ketones and Carboxylic Acids Chapter-Wise Test 16

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Arrange in decreasing order of acidity: \( \ce{CH3COOH} \), \( \ce{C6H5COOH} \), \( \ce{CH3CH2COOH} \).

Acidity increases with electron-withdrawing groups: \( \ce{C6H5COOH} \) (aromatic) > \( \ce{CH3COOH} \) > \( \ce{CH3CH2COOH} \) (alkyl reduces acidity).

\( \ce{CH3CH2COOH} \) > \( \ce{CH3COOH} \) > \( \ce{C6H5COOH} \)
\( \ce{CH3COOH} \) > \( \ce{C6H5COOH} \) > \( \ce{CH3CH2COOH} \)
\( \ce{CH3COOH} \) > \( \ce{CH3CH2COOH} \) > \( \ce{C6H5COOH} \)
\( \ce{C6H5COOH} \) > \( \ce{CH3COOH} \) > \( \ce{CH3CH2COOH} \)
4

Which compound does not give a positive Fehling’s test?

Fehling’s test is positive for aliphatic aldehydes. Acetone (\( \ce{CH3COCH3} \)), a ketone, does not reduce Fehling’s solution.

Ethanal
Acetone
Propanal
Methanal
2

What is the product of the Wolff-Kishner reduction of benzophenone?

Wolff-Kishner reduction (\( \ce{NH2NH2, KOH} \)) converts ketones to hydrocarbons. Benzophenone (\( \ce{C6H5COC6H5} \)) yields diphenylmethane (\( \ce{C6H5CH2C6H5} \)).

Benzyl alcohol
Diphenylmethane
Benzene
Benzophenone hydrazone
2

Which alkene produces pentan-2-one and methanal upon ozonolysis?

4-Methylpent-1-ene (\( \ce{CH2=CHCH2CH(CH3)2} \)) cleaves at the double bond, forming methanal (\( \ce{HCHO} \)) and pentan-2-one (\( \ce{CH3COCH2CH(CH3)2} \)).

1-Pentene
2-Methylbut-1-ene
4-Methylpent-1-ene
3-Methylbut-1-ene
3

Which compound gives a positive Schiff’s test and forms a primary alcohol in the Cannizzaro reaction?

Methanal (\( \ce{HCHO} \)) is an aldehyde (positive Schiff’s test) with no α-hydrogens, forming methanol (\( \ce{CH3OH} \)), a primary alcohol, via Cannizzaro reaction.

Ethanal
Propanal
Acetone
Methanal
4

Which pair of compounds can be distinguished by Tollens' test but not by Schiff’s test?

Hexanal (\( \ce{CH3CH2CH2CH2CH2CHO} \)) gives a positive Tollens' test (aldehyde), while hexan-2-one (\( \ce{CH3COCH2CH2CH2CH3} \)) does not; both are negative with Schiff’s (ketone) or positive (aldehyde), but Schiff’s isn’t differential here.

Ethanal and Propanal
Benzaldehyde and Methanal
Hexanal and Hexan-2-one
Acetone and Butanal
3

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

\( \ce{HCN} \) adds to the carbonyl group of butanal (\( \ce{CH3CH2CH2CHO} \)), forming a cyanohydrin, \( \ce{CH3CH2CH2CH(OH)CN} \).

Butanoic acid
Butanal cyanohydrin
Butan-1-ol
Butanone
2

What is the IUPAC name of \( \ce{CH3CH2CH2COCH2CH3} \)?

The longest chain with the ketone group has 6 carbons (hexan-3-one), with the carbonyl on C-3: hexan-3-one.

Hexan-3-one
Pentan-3-one
Hexan-2-one
Heptan-3-one
1

Which reagent converts butanoic acid to butanal in two steps?

Step 1: \( \ce{LiAlH4} \) reduces butanoic acid (\( \ce{CH3CH2CH2COOH} \)) to butan-1-ol (\( \ce{CH3CH2CH2CH2OH} \)). Step 2: PCC oxidizes it to butanal (\( \ce{CH3CH2CH2CHO} \)).

\( \ce{LiAlH4} \) followed by PCC
\( \ce{K2Cr2O7/H2SO4} \)
\( \ce{Zn(Hg), HCl} \)
\( \ce{NaBH4} \)
1

Which of the following is a product of the oxidation of pentan-1-ol with \( \ce{K2Cr2O7/H2SO4} \)?

Strong oxidation of a primary alcohol like pentan-1-ol (\( \ce{CH3CH2CH2CH2CH2OH} \)) with \( \ce{K2Cr2O7/H2SO4} \) yields pentanoic acid (\( \ce{CH3CH2CH2CH2COOH} \)).

Pentanoic acid
Pentanal
Pentan-2-one
Pentane
1

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