Aldehyde ketones & carboxylic Acid MCQs for NEET — Chemistry Questions with Answers

The given reaction is a Wittig reaction, where an ylide (Ph-CH=CHCHO + CH3CH=CHCHO) reacts with an aldehyde or ketone to form an alkene. The product formed is Ph-CH=CH-CHO, which is a styryl aldehyde or cinnamaldehyde.

(c) ${\mathrm{CH}}_3\mathrm{CHO}$$\stackrel{\mathrm{NaOH}}{\to }$CH₃$-{\mathrm{CH}}_3-\mathrm{CH}=\mathrm{CH}-\mathrm{CHO} \stackrel{{\mathrm{H}}_2/\mathrm{Ni}}{\to }{\mathrm{CH}}_3-{\mathrm{CH}}_2-{\mathrm{CH}}_2-{\mathrm{CH}}_2-\mathrm{OH}$

The Tollen's reagent test is a chemical test used to distinguish aldehydes from other carbonyl compounds like ketones. Only aldehydes give a positive test by forming a silver mirror on the inner walls of the test tube. Among the given options, only formic acid (HCO2H) is an aldehyde and will give a positive Tollen's test.

Acetaldehyde and benzaldehyde, both being aldehydes, can be differentiated by Fehling's test and iodoform test. Fehling's test distinguishes aldehydes from ketones, while the iodoform test differentiates between methyl ketones and other carbonyl compounds.

(a) $2{\mathrm{CH}}_3\mathrm{COOH}\underset{\mathrm{or} {\mathrm{ThO}}_2}{\overset{{\mathrm{Al}}_2{\mathrm{O}}_3 \mathrm{or} \mathrm{MnO}}{\to }}{\mathrm{CH}}_3{\mathrm{COCH}}_3 + {\mathrm{H}}_2\mathrm{O} + {\mathrm{CO}}_2$

(d) $\mathrm{RCHO}$ or $\mathrm{RCOR}$ can be reduced to ${\mathrm{RCH}}_2\mathrm{OH}$ or $\mathrm{RCHOHR}$ respectively by ${\mathrm{H}}_2$ + catalyst, ${\mathrm{LiAlH}}_4, {\mathrm{NaBH}}_4,$ etc.

Schiff's reagent is a magenta solution decolorized with sulfurous acid (SO2). It is used for the detection of aldehydes in organic compounds. When Schiff's reagent is added to an aldehyde-containing compound, it forms a colored compound, indicating the presence of the aldehyde group.

(c) Rest all are polymerization.

The molecular formula C3H6O can represent various compounds, including cyclic ether (e.g., oxirane), carbonyl compounds (e.g., acetone), unsaturated ethers (e.g., vinyl methyl ether), and unsaturated alcohols (e.g., propargyl alcohol). Therefore, the correct option is 'all of the above'.