This quiz works best with JavaScript enabled. Home > Cbse > Class 12 > Science > Chemistry Part Ii > Class 12 Chemistry (Part Ii) Chapter 12 Aldehydes – Quiz 1 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Class 12 Chemistry (Part Ii) Chapter 12 Aldehydes Quiz 1 (60 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. What observation indicates a positive Fehling's test? A) A red precipitate forms. B) The solution turns colourless. C) A silver mirror forms. D) A gas is released. Show Answer Correct Answer: A) A red precipitate forms. 2. Reaction of aldehydes with primary amine will results in the formation of A) An imine. B) An enamine. C) An ester. D) An oxime. Show Answer Correct Answer: A) An imine. 3. Which of the following will not give the iodoform test A) Acetophenone. B) Ethanal. C) Benzophenone. D) Ethanol. Show Answer Correct Answer: C) Benzophenone. 4. What is the name of the mechanism when KCN (in acidic conditions) reacts with propanal? A) Nucleophilic substitution. B) Electrophilic addition. C) Free radical substitution. D) Nucleophilic addition. Show Answer Correct Answer: D) Nucleophilic addition. 5. What type of reaction is involved in the dehydration of alcohols to form aldehydes or ketones? A) Elimination reaction. B) Oxidation reaction. C) Substitution reaction. D) Addition reaction. Show Answer Correct Answer: A) Elimination reaction. 6. What is the role of a catalyst in the oxidation of aldehydes? A) Speeds up the oxidation reaction by providing an alternative pathway with lower activation energy. B) Inhibits the oxidation reaction by increasing the activation energy. C) Has no effect on the oxidation reaction. D) Causes the oxidation reaction to proceed in the opposite direction. Show Answer Correct Answer: A) Speeds up the oxidation reaction by providing an alternative pathway with lower activation energy. 7. The oxidising agent in the Tollens' test for the presence of an aldehyde is ..... A) Cu$_{2}$O. B) Ag$^{+}$. C) Ag. D) Cu$^{2+}$. Show Answer Correct Answer: B) Ag$^{+}$. 8. When a tertiary alcohol reacts with acidified dichromate: A) The alcohol is not oxidised. B) The alcohol is oxidised to an aldehyde then a carboxylic acid. C) The alcohol is oxidised to a ketone. D) The alcohol is oxidised to an aldehyde. Show Answer Correct Answer: A) The alcohol is not oxidised. 9. The simplest aliphatic ketone A) Acetophenone. B) Acetone. C) Butanone. D) Benzophenone. Show Answer Correct Answer: B) Acetone. 10. When ethanoic acid reacts with magnesium, which gas is released? A) Hydrogen. B) Oxygen. C) Carbon dioxide. D) Nitrogen. Show Answer Correct Answer: A) Hydrogen. 11. Reaction of a carboxylic acid and a primary amine will produce: A) An amide if heat is added. B) A tertiary amine. C) A substituted ammonium salt if heat is added. D) A secondary amine. Show Answer Correct Answer: A) An amide if heat is added. 12. The correct order of acidic strength of carboxylic acids is A) Acetic acid < Formic acid < benzoic acid. B) Acetic acid < benzoic acid < Formic acid. C) Formic acid < benzoic acid < acetic acid. D) Formic acid < acetic acid < benzoic acid. Show Answer Correct Answer: B) Acetic acid < benzoic acid < Formic acid. 13. Which alcohol must be oxidized to obtain propanone (acetone)? A) Ethanol. B) 1-propanol. C) 1-butanol. D) 3-butanol. E) 2-propanol. Show Answer Correct Answer: E) 2-propanol. 14. The Clemmenson reduction of acetone yields A) Ethanol. B) Propane. C) Propanol. D) Ethanal. Show Answer Correct Answer: B) Propane. 15. What happens when carbon dioxide is tested with a lighted taper? A) A 'pop' sound is heard. B) The flame burns brighter. C) The flame goes out. D) The flame turns blue. Show Answer Correct Answer: C) The flame goes out. 16. The product formed in Aldol condensation is A) A beta hydroxy acid. B) An alpha, beta-unsaturated ester. C) A beta hydroxy aldehyde or ketone. D) An alpha hydroxy aldehyde or ketone. Show Answer Correct Answer: C) A beta hydroxy aldehyde or ketone. 17. On oxidizing compound X with CrO$_{3 }$, compound Y is obtained. Compound Y does not react with Tollens reagent. X and Y are most likely to be, A) X:CH$_{3}$CH(OH)CH$_{3}$ Y:CH$_{3}$COCH$_{3}$. B) X:CH$_{3}$CH$_{2}$CH$_{2}$OH Y:CH$_{3}$CH$_{2}$CHO. C) X:CH$_{3}$CH(OH)CH$_{3}$ Y:CH$_{3}$CH$_{2}$CHO. D) X:CH$_{3}$CH$_{2}$CH$_{2}$OH Y:CH$_{3}$COCH$_{3}$. Show Answer Correct Answer: A) X:CH$_{3}$CH(OH)CH$_{3}$ Y:CH$_{3}$COCH$_{3}$. 18. The only aldehyde that gives positive result with I$_{2}$/NaOH is A) Butanal. B) 2-methylpropanal. C) Propanal. D) Ethanal. Show Answer Correct Answer: D) Ethanal. 19. What is R?CH$_{3}$CH$_{2}$COH + R $\rightarrow$ CH$_{3}$CH$_{2}$COOH A) Grignard reagent. B) LiAlH$_{4}$. C) Na$_{2}$Cr$_{2}$O$_{7}$ / H$^{+}$. D) NaBH$_{4}$. Show Answer Correct Answer: C) Na$_{2}$Cr$_{2}$O$_{7}$ / H$^{+}$. 20. What is the key reagent used in the Stephen reaction for aldehyde synthesis? A) Bromine (Br2). B) Iodine (I2). C) Chlorine (Cl2). D) Sodium hydroxide (NaOH). Show Answer Correct Answer: A) Bromine (Br2). 21. Which reagent is NOT commonly used for the oxidation of primary alcohols to aldehydes? A) Sodium ethanoate (CH3COONa). B) Potassium permanganate (KMnO4). C) Potassium dichromate (K2Cr2O7). D) PCC (pyridinium chlorochromate). Show Answer Correct Answer: A) Sodium ethanoate (CH3COONa). 22. Alcohol forms over time through the process of fermentation, when ..... sugars breakdown. A) Fat. B) Protein. C) Carbohydrate. D) Blood. Show Answer Correct Answer: C) Carbohydrate. 23. Which of the following tests would give a positive result for propan-1-ol? A) PCl$_{5}$ (phosphorus pentachloride). B) The iodoform test (NaOH + I$_{2}$). C) Tollen's reagent (silver mirror test). D) 2, 4-DNPH (Brady's reagent). Show Answer Correct Answer: A) PCl$_{5}$ (phosphorus pentachloride). 24. Explain the effect of branching on the boiling point of ketones. A) Branching increases the boiling point of ketones. B) Branching has no effect on the boiling point of ketones. C) Branching decreases the boiling point of ketones. D) Branching makes the boiling point of ketones unstable. Show Answer Correct Answer: C) Branching decreases the boiling point of ketones. 25. What observation suggests a gas is being produced when ethanoic acid reacts with sodium carbonate? A) Temperature change. B) Formation of a precipitate. C) Colour change. D) Fizzing or bubbling. Show Answer Correct Answer: D) Fizzing or bubbling. 26. What is the difference between aldehyde and ketones?b. position of C atomsc. the number of bonds carbon can formd. the number of oxygen atoms A) A. position of C=O group. B) B. position of C atoms. C) D. the number of oxygen atoms. D) The number of bonds carbon can form. Show Answer Correct Answer: A) A. position of C=O group. 27. What is the role of acetyl chloride in Friedel-Crafts Acylation? A) Acetyl chloride acts as a reducing agent in Friedel-Crafts Acylation. B) Acetyl chloride is used as a catalyst in Friedel-Crafts Acylation. C) Acetyl chloride serves as a solvent in Friedel-Crafts Acylation. D) Acetyl chloride acts as the acylating agent by forming an acylium ion in the presence of a Lewis acid catalyst. Show Answer Correct Answer: D) Acetyl chloride acts as the acylating agent by forming an acylium ion in the presence of a Lewis acid catalyst. 28. What is the color & formula of the ppt formed when Acetone reacted with Iodine & NaOH? A) Yellow & CH$_{3}$I. B) Yellow & HCOI. C) White & CI$_{4}$. D) Yellow & CHI$_{3}$. Show Answer Correct Answer: D) Yellow & CHI$_{3}$. 29. Salicylaldehyde can be produced directly from phenol. A) True. B) False. C) All the above. D) None of the above. Show Answer Correct Answer: B) False. 30. The products of the reaction of a carboxylic acid and an alcohol would be A) Ketone and water. B) Amide and water. C) Acid chloride and water. D) Ester and water. Show Answer Correct Answer: D) Ester and water. 31. What is the chemical name for Brady's reagent? A) 2, 4-diphenylhydrazine. B) 2, 4-dinitrophenyhydrazone. C) 2, 4-dinitrophenolhydrazine. D) 2, 4-dinitrophenyhydrazine. Show Answer Correct Answer: D) 2, 4-dinitrophenyhydrazine. 32. Select carbonyl compounds from the following formulae: A) C$_{4}$H$_{8}$. B) C$_{4}$H$_{10}$O. C) C$_{4}$H$_{8}$O$_{2}$. D) C$_{4}$H$_{8}$O. Show Answer Correct Answer: D) C$_{4}$H$_{8}$O. 33. What is the general formula for carboxylic acids? A) CnH2nO. B) CnH2nO2. C) CnH2nO3. D) CnH2nO4. Show Answer Correct Answer: B) CnH2nO2. 34. What is the main product when ethanoic acid reacts with ethanol in the presence of an acid catalyst? A) Ethyl ethanoate. B) Acetaldehyde. C) Acetone. D) Ethyl acetate. Show Answer Correct Answer: A) Ethyl ethanoate. 35. Which statement helps to explain why chloroethanoic acid is a stronger acid than ethanoic acid? A) Chlorine has a large electron cloud size. B) Chlorine exerts an electron-withdrawing effect to stabilise the chloroethanoate ion. C) The negative charge is dispersed over 2 highly electronegative oxygen atoms. D) Chloroethanoic acid has a higher pKa value than ethanoic acid. Show Answer Correct Answer: B) Chlorine exerts an electron-withdrawing effect to stabilise the chloroethanoate ion. 36. Which of the following acids is the most soluble in water? A) Benzoic acid. B) Ethanoic acid. C) Pentanoic acid. D) Hexanoic acid. Show Answer Correct Answer: B) Ethanoic acid. 37. What observation confirms the presence of hydrogen gas? A) A 'pop' sound with a lighted taper. B) Limewater turns milky. C) Silver mirror forms. D) Flame goes out. Show Answer Correct Answer: A) A 'pop' sound with a lighted taper. 38. Discuss the solubility of carboxylic acids in water. A) Carboxylic acids are insoluble in water. B) Carboxylic acids partially dissolve in water. C) Carboxylic acids form a suspension in water. D) Carboxylic acids are soluble in water. Show Answer Correct Answer: D) Carboxylic acids are soluble in water. 39. Which one is a good reducing agent? A) KMnO$_{4 }$. B) K$_{2}$Cr$_{2}$O$_{7}$. C) Pt. D) NaBH$_{4}$. E) O$_{2}$. Show Answer Correct Answer: D) NaBH$_{4}$. 40. In Tollen's test, what happens to the silver ions (Ag+)? A) They dissolve. B) They form a gas. C) They are oxidised. D) They are reduced to silver metal. Show Answer Correct Answer: D) They are reduced to silver metal. 41. Which of the following organic compound shows rapid reaction with sodium nitroprusside? A) Formaldehyde. B) Acetaldehyde. C) Benzaldehyde. D) Acetone. Show Answer Correct Answer: D) Acetone. 42. The number of carbon atoms present in glutaric acid is A) 5. B) 3. C) 4. D) 6. Show Answer Correct Answer: A) 5. 43. The acidity of carboxylic acids is stronger than that of alcohols because of: A) Presence of a carbonyl group. B) Presence of a hydroxyl group. C) Lower boiling point. D) More carbon atoms in the chain. Show Answer Correct Answer: B) Presence of a hydroxyl group. 44. Which aldehyde is a gas at room temperature? A) Acetaldehyde. B) Formaldehyde. C) Benzaldehyde. D) None of the above. Show Answer Correct Answer: B) Formaldehyde. 45. The following statement is NOT suitable for Cannizzaro's reaction. A) Absence of $\alpha$-H. B) In presence of strong alkali. C) In presence of dilute alkali. D) Self oxidation and reduction. Show Answer Correct Answer: C) In presence of dilute alkali. 46. Compare the acidity of carboxylic acids with alcohols. A) Carboxylic acids are more acidic than alcohols. B) Alcohols are less acidic than carboxylic acids. C) Carboxylic acids and alcohols have the same level of acidity. D) Alcohols are more acidic than carboxylic acids. Show Answer Correct Answer: A) Carboxylic acids are more acidic than alcohols. 47. When the carbonyl group of a neutral ketones get protonated: A) The resulting species becomes more electrophilic. B) The resulting species is deactivated towards nucleophilic attacked. C) The resulting species carries negative charges. D) The resulting species becomes less electrophilic. Show Answer Correct Answer: A) The resulting species becomes more electrophilic. 48. The solution used to preserve biological specimen is A) Acetone. B) Vanillin. C) Tollens reagent. D) Formalin. Show Answer Correct Answer: D) Formalin. 49. Which of the following statements about synthesis of aldehydes is CORRECT? A) Stephen reduction in presence of SnCl$_{2}$ and HCl. B) Etard reaction in presence of CrO$_{2}$Cl$_{2}$ in CS$_{2}$. C) Rosenmund reduction in presence of Pd + BaSO$_{4}$. D) All of above. Show Answer Correct Answer: D) All of above. 50. Boiling points of carboxylic acids is higher than those of their corresponding alcohols due to A) Strong dipole-dipole interactions between molecules. B) Strongly hydrogen bonded dimers. C) Strong London dispersion forces. D) Strong covalent bonds between molecules. Show Answer Correct Answer: B) Strongly hydrogen bonded dimers. 51. Which of the following statements about aldehydes and ketones is INCORRECT? A) Both can form hydrogen bonds. B) Aldehydes have a higher boiling point than ketones with similar chain lengths. C) Both can undergo nucleophilic addition reactions. D) Ketones have two sp2 hybridized carbon atoms. Show Answer Correct Answer: B) Aldehydes have a higher boiling point than ketones with similar chain lengths. 52. Aldehyde carbonyl group is always positioned at A) Center of the chain. B) All over the chain. C) End of the chain. D) Anywhere on the chain. Show Answer Correct Answer: C) End of the chain. 53. How can a primary alcohol be oxidized to form an aldehyde? A) Heating the alcohol with a base. B) Using an oxidizing agent such as PCC or CrO3 in an appropriate solvent. C) Using a reducing agent such as NaBH4. D) Adding a catalyst like H2SO4. Show Answer Correct Answer: B) Using an oxidizing agent such as PCC or CrO3 in an appropriate solvent. 54. To differentiate between pentan-2-one and penta-3-one a test is carried out. Which of the following is the correct answer? A) Pentan-2-one will give silver mirror test. B) Pentan-2-one will give iodoform test. C) Pentan-3-one will give iodoform test. D) None of these. Show Answer Correct Answer: B) Pentan-2-one will give iodoform test. 55. Tollen's reagent is used to identify the presence of aldehyde by giving the result of A) Brown precipitate. B) Yellow precipitate. C) Silver mirror. D) Cloudy. Show Answer Correct Answer: C) Silver mirror. 56. Aldehydes are easily oxidized to carboxylic acids by the same reagent which is: A) Salicylaldehyde. B) Butanal. C) Acidic dichromatic. D) Acetone. Show Answer Correct Answer: C) Acidic dichromatic. 57. Which type of carboxylic acid reduction leads to the formation of aldehydes? A) H2SO4 hydrolysis. B) K2Cr2O7 oxidation. C) PCC oxidation. D) LiAlH4 or NaBH4 reduction. Show Answer Correct Answer: D) LiAlH4 or NaBH4 reduction. 58. Which of the following reactions involves the conversion of an aldehyde to a carboxylic acid? A) Reduction. B) Oxidation. C) Hydrolysis. D) Dehydration. Show Answer Correct Answer: B) Oxidation. 59. When nucleophilic addition to the carbonyl group occurs, the carbon attacked undergoes what hybridization change? A) Sp to sp3. B) Sp to sp2. C) Sp2 to sp. D) Sp2 to sp3. Show Answer Correct Answer: D) Sp2 to sp3. 60. Which of the following reactions are not used to reduce aldehydes to hydrocarbons A) Wolff-Kishner reduction. B) Rosenmund reduction. C) With HI + Red P. D) Cemmensen reduction. Show Answer Correct Answer: B) Rosenmund reduction. 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