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

Complete each synthesis by giving missing starting material, reagent, or products: (I) \(\text{CH}_3\text{CH}_3 + \text{KMnO}_4, \text{KOH} \longrightarrow \text{?}\)
An aromatic compound A$^1$ with molecular formula C$_8$H$_8$O gives positive 2,4-DNP test. It gives yellow precipitate of compound ‘B’ on treatment with sodium hypobromite. Compound ‘A’ does not react with Tollen’s or Fehling’s reagent; on drastic oxidation with KMnO$_4$, it forms a carboxylic acid ‘C’. Elucidate the structures of A, B and C. Also give their IUPAC names.

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

Give a simple chemical test to distinguish between propanal and propanone.
Give IUPAC name of CH\(_3\)–CH=CH–CHO.
Write the structures of A, B, and C in the following sequence of reactions: (a) \(\text{CH}_3\text{COOH} \xrightarrow{\text{SOCl}_2} A \xrightarrow{\text{H}_2, \text{Pd-BaSO}_4} B \xrightarrow{\text{H}_2\text{N-NH}_2} C\)
(b) \(\text{CH}_3\text{CN} \xrightarrow{1.\text{DIBAL-H}} A \xrightarrow{2.\text{H}_2\text{O}} B \xrightarrow{\Delta} C\)
(A) Explain the following reactions and write chemical equations involved: (a) Wolff-Kishner reduction
(b) Etard reaction
(c) Cannizzaro reaction

Convert Ethanal to But-2-enal

Would you expect benzaldehyde to be more reactive or less reactive in nucleophilic addition reactions than propanal? Justify your answer.
The acid formed when propyl magnesium bromide is treated with CO$_2$ followed by acid hydrolysis is:
Give IUPAC name of \( CH_3 = CH - CH = CH - CHO \).
Explain the following reactions and write chemical equations involved:
(a) Wolff-Kishner reduction
(b) Etard reaction
(c) Cannizzaro reaction
Write the chemical equations when: Pentan-3-one is treated with H$_2$N–NH$_2$ followed by heating with KOH in high boiling solvent such as ethylene glycol.
Compound (A) \( \left( \text{C}_6\text{H}_{12}\text{O}_2 \right) \) on reduction with LiAlH4 gives two compounds (B) and (C). The compound (B) on oxidation with PCC gives compound (D) which upon treatment with dilute NaOH and subsequent heating gives compound (E). Compound (E) on catalytic hydrogenation gives compound (C). The compound (D) is oxidized further to give compound (F) which is found to be a monobasic acid (Molecular weight = 60). Identify the compounds (A), (B), (C), (D), (E) and (F).
The IUPAC name of CH$_3$–C(=O)–CH$_2$–C(=O)–H is:
Decarboxylation of sodium benzoate on heating with soda lime gives:
The product formed as a result of reaction of CH$_3$MgBr and CO$_2$ followed by hydrolysis is:
Give a simple chemical test to distinguish between ethanoic acid and ethanal.
Draw structure of the 2,4-dinitrophenylhydrazone of benzaldehyde.
How can you convert phenyl magnesium bromide to benzoic acid?
Arrange the following in increasing order of their reactivity towards HCN: \[ \text{CH}_3\text{COCH}_3, \, (\text{CH}_3)_3\text{C} - \text{COCH}_3, \, \text{CH}_3\text{CHO} \]
Out of [Co(NH\(_3\))\(_6\)]\(^{3+}\) and [Co(NH\(_3\))\(_4\)Cl\(_2\)]\(^+\), which complex is heteroleptic and why?
Draw the structures of optical isomers of [PtCl\(_2\)(en)\(_2\)]\(^{2+}\).
Account for the following:
1. Oxidation of aldehydes is easier as compared to ketones.
2. The alpha (α) hydrogen atoms of aldehydes are acidic in nature.
Write the products in the following reactions:
reaction of acetophenone