MHT CET202616 April 2026Morning ShiftChemistryAldehydes and KetonesActual
Which of following observations is found in Tollens test for aldehydes?
Options
- AThe formation of pink or magenta color upon the addition of the reagent to the sample solution.
- BFormation of an Ag layer on sides of test tube upon addition and warming of the reagent.
- CFormation of brick-red precipitate upon heating with reagent.
- DAppearance of red color upon shaking with reagent.
Correct answer
B. Formation of an Ag layer on sides of test tube upon addition and warming of the reagent.
Step-by-step solution
Tollens' reagent is an ammoniacal silver nitrate solution, [Ag(NH₃)₂]^+ . When an aldehyde is warmed with Tollens' reagent, the aldehyde is oxidized to the corresponding carboxylate ion, while the silver ions are reduced to metallic silver. RCHO + 2[Ag(NH₃)₂]^+ + 3OH^- RCOO^- + 2Ag + 4NH₃ + 2H₂O The metallic silver deposits on the inner walls of the test tube, forming a characteristic silver mirror or an Ag layer. This observation confirms the presence of an aldehyde group. The formation of a pink or magenta color