List of top Chemistry Questions on Aldehydes, Ketones and Carboxylic Acids asked in CBSE CLASS XII

Benzoic acid to Benzene
Which of the reactions is used in the conversion of a ketone into hydrocarbon?
Draw the structure of 'X' in the following reaction:
Write the name of the reagent to convert Ethanenitrile to Ethanal.
Give a simple chemical test to distinguish between benzoic acid and ethyl benzoate.
Arrange the following in increasing order of their reactivity towards HCN:
Di-tert. butyl ketone, Acetaldehyde, Acetone
Draw structure of the 2, 4-dinitrophenyl hydrazone derivative of benzaldehyde.
Show how each of the following compounds can be converted to benzoic acid:
(I) Acetophenone
(II) Ethyl benzene
An organic compound (X) has the molecular formula \(C_5H_{10}O\). Draw structures for (X) if it:
(I) does not give Tollen's test but gives a positive iodoform test.
(II) does not give Tollen's test and iodoform test but undergoes Aldol condensation.
(III) undergoes Cannizzaro's reaction.
Nucleophilic addition of ammonia and its derivatives does not occur with carbonyl group in strongly acidic medium.
Alpha (\(\alpha\)) hydrogens of aldehydes and ketones are acidic in nature.

Give reason of the following
Carboxylic acids have higher boiling point than alcohols of comparable molecular masses. 
 

Arrange the following compounds in increasing order of their acidic strengths: \[ CH_3CH_2COOH,\quad CH_3CH(CH_3)COOH,\quad CH_3CH_2CH_2COOH,\quad BrCH_2CH_2COOH \]
Answer the following questions:
(i) Draw structure of the methyl hemiactetal of methanal.
(ii) There are two -NH$_2$ groups in semicarbazide. However, only one is involved in the formation of semicarbazones. Give reason.
(iii) How will you convert ethanol to 3-hydroxybutanal?

In the given reaction sequence, the structure of Y would be:

The acid formed when propyl magnesium bromide is treated with CO$_2$ followed by acid hydrolysis is:
Complete each synthesis by giving missing starting material, reagent, or products: (I) \(\text{CH}_3\text{CH}_3 + \text{KMnO}_4, \text{KOH} \longrightarrow \text{?}\)
Would you expect benzaldehyde to be more reactive or less reactive in nucleophilic addition reactions than propanal? Justify your answer.

Convert Ethanal to But-2-enal

Write the reaction involved in the following :
Clemmensen reduction
An organic compound (X) having molecular formula C$_5$H$_{10$O can show various properties depending on its structures. Draw each of the structures if it :
shows Cannizzaro reaction.

Write structure of the products of the following reactions:

Vinyl group directly attached with carboxylic acid should decrease acidity due to resonance, but it increases acidity. Explain.
Give reasons for the following:HCHO is more reactive than CH$_3$CHO towards addition of HCN.
Give reasons for the following:
Benzoic acid does not undergo Friedel-Crafts reaction.