Aldehydes, Ketones and Carboxylic Acids Chapter-Wise Test 17

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which test produces a silver mirror with pentanal but not with pentan-2-one?

Tollens' test oxidizes aldehydes like pentanal (\( \ce{CH3CH2CH2CH2CHO} \)) to carboxylic acids, forming a silver mirror, but does not react with ketones like pentan-2-one.

Iodoform test
Fehling’s test
Tollens' test
2,4-DNP test
3

Which aldehyde forms a chiral cyanohydrin upon reaction with \( \ce{HCN} \)?

Propanal (\( \ce{CH3CH2CHO} \)) reacts with \( \ce{HCN} \) to form \( \ce{CH3CH2CH(OH)CN} \), which has a chiral carbon (four different groups: OH, CN, H, \( \ce{CH2CH3} \)).

Propanal
Methanal
Acetone
Benzophenone
1

Which compound is formed by the ozonolysis of 1-butene followed by hydrolysis?

Ozonolysis of 1-butene (\( \ce{CH2=CHCH2CH3} \)) cleaves the double bond, forming methanal (\( \ce{HCHO} \)) and propanal (\( \ce{CH3CH2CHO} \)).

Ethanal
Acetone
Propanal
Butanal
3

How is benzaldehyde converted to benzophenone in two steps?

Step 1: Oxidize benzaldehyde (\( \ce{C6H5CHO} \)) to benzoic acid (\( \ce{C6H5COOH} \)) with Tollens' reagent. Step 2: React with phenylmagnesium bromide and hydrolyze to form benzophenone (\( \ce{C6H5COC6H5} \)).

Reduction then dehydration
Aldol condensation then oxidation
Grignard reaction then reduction
Oxidation then Grignard reaction
4

Which compound does not undergo aldol condensation?

Aldol condensation requires α-hydrogens. Benzaldehyde (\( \ce{C6H5CHO} \)) lacks α-hydrogens and undergoes Cannizzaro reaction instead.

Propanal
Benzaldehyde
Acetone
Butanal
2

Which test produces a pink color with aldehydes but not with ketones?

Schiff’s test restores a pink color with aldehydes (e.g., ethanal) due to their reactivity, but not with ketones (e.g., acetone).

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

Which ketone, when treated with \( \ce{SeO2} \), yields a dicarbonyl compound with five carbon atoms?

\( \ce{SeO2} \) oxidizes the α-carbon of pentan-2-one (\( \ce{CH3COCH2CH2CH3} \)) to form \( \ce{CH3COCH2COCH3} \) (pentane-2,4-dione), a five-carbon dicarbonyl.

Butan-2-one
Pentan-2-one
Pentan-3-one
Hexan-3-one
2

Which compound is produced when benzoic acid reacts with \( \ce{LiAlH4} \)?

\( \ce{LiAlH4} \) reduces carboxylic acids to primary alcohols. Benzoic acid (\( \ce{C6H5COOH} \)) yields benzyl alcohol (\( \ce{C6H5CH2OH} \)).

Benzaldehyde
Benzene
Benzyl alcohol
Benzophenone
3

Which compound gives a positive 2,4-DNP test but not a Fehling’s test?

Acetophenone (\( \ce{C6H5COCH3} \)) is a ketone (positive 2,4-DNP test) but does not reduce Fehling’s solution (negative Fehling’s test).

Ethanal
Propanal
Benzaldehyde
Acetophenone
4

Arrange in increasing order of reactivity towards \( \ce{HCN} \): \( \ce{CH3COCH3} \), \( \ce{CH3CHO} \), \( \ce{(CH3)2CHCHO} \).

Reactivity decreases with steric hindrance: \( \ce{CH3COCH3} \) (ketone) < \( \ce{(CH3)2CHCHO} \) (branched aldehyde) < \( \ce{CH3CHO} \) (simple aldehyde).

\( \ce{CH3CHO} \) < \( \ce{(CH3)2CHCHO} \) < \( \ce{CH3COCH3} \)
\( \ce{(CH3)2CHCHO} \) < \( \ce{CH3COCH3} \) < \( \ce{CH3CHO} \)
\( \ce{CH3COCH3} \) < \( \ce{(CH3)2CHCHO} \) < \( \ce{CH3CHO} \)
\( \ce{CH3COCH3} \) < \( \ce{CH3CHO} \) < \( \ce{(CH3)2CHCHO} \)
3

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