JEE Questions for Chemistry Aldehydes Ketones And Carboxylic Acids Quiz 12 - MCQExams.com

Reactivity decreases as the magnitude of +ve charge on the carbonyl carbon decreases or the steric hindrance in the intermediate increases,
i.e., H₂C=O > RCHO > ArCHO > R₂C=O > Ar₂C=O

Since compound Y on treatment with I₂ and Na₂CO₃ gives CHI₃, therefore, it must contain the grouping CH₃CO-,Since compound Y is obtained from X by oxidation with K₂Cr₂O₇,therefore,X must contain the grouping CH₃CHOH–. Thus option (d) is correct.

HCHO does not contain α-hydrogen and hence does not undergo aldol condensation

Luca’s test is characteristic of alcohols. Therefore acetaldehyde does not give this test.

Optimum pH for oxime formation is around 3.5.Therefore, option (b) with a pH value of 4.5 is correct.

HCHO is most reactive towards nucleophilic addition reactions.

As the + I - effect of the CH₃ group increases and steric hindrance in the tetrahedral intermediate increases, the reactivity decreases,

i.e., HCHO (I) > CH₃CHO (II) > CH₃COCH₃ (III)

2HCHO + NaOH → HCOONa + CH₃OH

CH₃CHO contains α −hydrogens and hence does not undergo Cannizzaro

Formaldehyde which does not contain α − hydrogen does not undergo aldol condensation

Acetaldehyde does not undergo Cannizzaro reaction since it contains Hα− atoms while formaldehyde, trimethylacetaldehyde and benzaldehyde undergo Cannizzaro reaction since they do not contain α− hydrogen atoms

I (Etard reaction)-C-(chromyl chloride ),
II (hydroxylation )-D (dilute alkaline KMnO₄),
III.(dehydro-halogenation)–A (alcoholic KOH ),
IV. (Friedel-Crafts reaction)-B (anhydrous AlCl₃) .Thus, option (c) is correct.

I - C (Clemmensen reduction), II - D (Cannizzaro reaction), III-A (Friedel-Crafts reaction). IV-B (Kolbe’s reaction).Thus, option (c) is correct.

With Fehling’s solution, red ppt. of Cu₂O are produced

Wolff-Kishner reduction.

Due to electron-withdrawing nature of NO₂ group, the partial +ve charge on the carbon atom of the C = O group in p-nitrobenzaldehyde increases and hence becomes more susceptible to nucleophilic attack by the CN- ion.