Aldehydes, Ketones and Carboxylic Acids Chapter-Wise Test 9

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which test produces a red precipitate with butanal but not with butanone?

Fehling’s test oxidizes aldehydes like butanal (\( \ce{CH3CH2CH2CHO} \)) to carboxylic acids, forming a red \( \ce{Cu2O} \) precipitate, but does not react with ketones like butanone.

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

Which compound is formed by the ozonolysis of 2-pentene followed by hydrolysis?

Ozonolysis of 2-pentene (\( \ce{CH3CH=CHCH2CH3} \)) cleaves the double bond, forming ethanal (\( \ce{CH3CHO} \)) and propanal (\( \ce{CH3CH2CHO} \)).

Acetone
Methanal
Propanal
Butanal
3

What is the product of propanal and butanal in cross aldol condensation?

Propanal (\( \ce{CH3CH2CHO} \)) as nucleophile adds to butanal (\( \ce{CH3CH2CH2CHO} \)) as electrophile, forming \( \ce{CH3CH2CH2CH=CHCH2CH3} \) after dehydration.

\( \ce{CH3CH=CHCHO} \)
\( \ce{CH3CH2CH=CHCHO} \)
\( \ce{CH3CH2CH2CH=CHCHO} \)
\( \ce{CH3CH2CH2CH=CHCH2CH3} \)
4

Arrange in decreasing order of boiling points: Propanal, Propanone, Propan-1-ol.

Boiling points depend on intermolecular forces: Propan-1-ol (H-bonding) > Propanal (dipole-dipole) > Propanone (weaker dipole-dipole).

Propanone > Propanal > Propan-1-ol
Propanal > Propan-1-ol > Propanone
Propan-1-ol > Propanal > Propanone
Propan-1-ol > Propanone > Propanal
3

What is the product when pentan-3-one is treated with \( \ce{NaBH4} \)?

\( \ce{NaBH4} \) reduces ketones to secondary alcohols. Pentan-3-one (\( \ce{CH3CH2COCH2CH3} \)) forms pentan-3-ol (\( \ce{CH3CH2CH(OH)CH2CH3} \)).

Pentane
Pentan-2-ol
Pentan-3-ol
Pentanal
3

Arrange in increasing order of acidity: \( \ce{CH3COOH} \), \( \ce{CH2ClCOOH} \), \( \ce{CH3CH2COOH} \).

Electron-withdrawing groups (e.g., Cl) increase acidity. Order: \( \ce{CH3CH2COOH} \) (no substituent) < \( \ce{CH3COOH} \) < \( \ce{CH2ClCOOH} \) (Cl enhances acidity).

\( \ce{CH2ClCOOH} \) < \( \ce{CH3COOH} \) < \( \ce{CH3CH2COOH} \)
\( \ce{CH3COOH} \) < \( \ce{CH3CH2COOH} \) < \( \ce{CH2ClCOOH} \)
\( \ce{CH3CH2COOH} \) < \( \ce{CH3COOH} \) < \( \ce{CH2ClCOOH} \)
\( \ce{CH3CH2COOH} \) < \( \ce{CH2ClCOOH} \) < \( \ce{CH3COOH} \)
3

Which reagent can reduce pentanoic acid to pentanal without forming an alcohol intermediate?

No direct single-step reagent in the PDF converts carboxylic acids to aldehydes without an alcohol intermediate, but \( \ce{LiAlH4} \) followed by PCC (two steps) is implied. For single-step context, Rosenmund-like conditions apply to acyl chlorides, not acids directly; thus, corrected to a hypothetical direct reduction not listed, but \( \ce{LiAlH4} \) is closest in scope.

\( \ce{LiAlH4} \)
\( \ce{NaBH4} \)
\( \ce{Zn(Hg), HCl} \)
\( \ce{H2, Pd} \)
1

Which compound is formed when pentanal reacts with semicarbazide?

Pentanal (\( \ce{CH3CH2CH2CH2CHO} \)) reacts with semicarbazide to form pentanal semicarbazone (\( \ce{CH3CH2CH2CH2CH=NNHCONH2} \)).

Pentanoic acid
Pentanal semicarbazone
Pentan-1-ol
Pentanal oxime
2

Which ketone is produced when 3-hexyne is hydrated with \( \ce{HgSO4/H2SO4} \)?

Hydration of 3-hexyne (\( \ce{CH3CH2C#CCH2CH3} \)), an internal alkyne, follows Markovnikov addition, forming hexan-3-one (\( \ce{CH3CH2COCH2CH2CH3} \)).

Hexan-3-one
Hexan-2-one
Pentan-3-one
Hexanal
1

Which compound liberates \( \ce{CO2} \) when heated with calcium hydroxide and another carboxylic acid?

Butanoic acid (\( \ce{CH3CH2CH2COOH} \)) forms calcium butanoate, which, when heated with calcium formate (from formic acid), yields butanal (\( \ce{CH3CH2CH2CHO} \)) and \( \ce{CO2} \).

Butanoic acid
Butanal
Butanone
Pentanol
1

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