Free Preparation of Aldehydes and Ketones MCQs with Answers
16 Preparation of Aldehydes and Ketones MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Aldehydes and ketones are prepared mainly by controlled oxidation or dehydrogenation of primary and secondary alcohols, respectively. The topic also includes ozonolysis of alkenes, hydration of alkynes and preparation through acyl derivatives, with attention to why primary alcohols can give aldehydes whereas secondary alcohols give ketones.
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16 questions
- A. ethanol
- B. ethanoic acid
- C. ethene with hydrogen
- D. propanone
Explanation: Oxidising the primary alcohol ethanol with acidified dichromate, distilling off the product as it forms, gives ethanal, and the same…
Correct answer: ethanol- A. propan-1-ol
- B. propane
- C. propan-2-ol
- D. propanoic acid
Explanation: Propan-2-ol is a secondary alcohol, so removing the hydrogen from the carbinol carbon leaves a ketone, and the reaction stops there…
Correct answer: propan-2-ol- A. preserving biological specimens
- B. flavouring food
- C. treating drinking water
- D. use as a fuel
Explanation: Methanal cross links the proteins of tissue, hardening it and killing microorganisms, which is why formalin preserves specimens and is…
Correct answer: preserving biological specimens- A. a solvent, because it dissolves both polar and non polar substances and evaporates quickly
- B. an oxidising agent
- C. a fuel for vehicles
- D. a food preservative
Explanation: Its polar carbonyl group and small hydrocarbon portion let propanone dissolve a wide range of materials, and its low boiling point of 56…
Correct answer: a solvent, because it dissolves both polar and non polar substances and evaporates quickly- A. CH4
- B. C2H6
- C. C2H4
- D. C2H2
Explanation: Ethyne reacts with dilute H2SO4 in the presence of HgSO4 by acid-catalysed hydration, initially forming an enol that rearranges to…
Correct answer: C2H2- A. Carboxylic acid
- B. Acetaldehyde
- C. Formaldehyde
- D. Ketone
Explanation: Urotropine, or hexamethylenetetramine, is formed by the condensation of formaldehyde with ammonia: 6HCHO + 4NH3 → (CH2)6N4 + 6H2O.
Correct answer: Formaldehyde- A. PdCl2
- B. Cu2Cl2
- C. CuCl2
- D. PbCl2
Explanation: Industrial oxidation of ethene to ethanal by the Wacker process uses PdCl2 as the catalyst and CuCl2 as the promoter or co-oxidant.
Correct answer: CuCl2- A. 60%
- B. 50%
- C. 52%
- D. 8%
Explanation: Commercial formalin usually contains 40% formaldehyde and about 8% methanol, so water makes up the remainder: 100% - 40% - 8% = 52% water.
Correct answer: 52%- A. formamint
- B. lactomint
- C. aldomint
- D. formalactose
Explanation: Formaldehyde combined with lactose produces Formamint, a well-known antiseptic throat lozenge.
Correct answer: formamint- A. 10%
- B. 20%
- C. 40%
- D. 60%
Explanation: Formalin is conventionally a concentrated aqueous solution containing about 40% formaldehyde by mass, often stabilized with a small amount…
Correct answer: 40%- A. formaldehyde
- B. acetaldehyde
- C. methane
- D. acetone
Explanation: On dry distillation, calcium acetate undergoes ketonic decarboxylation: (CH3COO)2Ca gives CH3COCH3, acetone, along with calcium carbonate.
Correct answer: acetone- A. Primary alcohols
- B. Secondary alcohols
- C. Organic acids
- D. Inorganic acids
Explanation: Consider any 1° alcohol. For simplicity consider it to be open-chain alcohol.
Correct answer: Primary alcohols- A. Acetaldehyde.
- B. Formaldehyde.
- C. None of these.
- D. Both A and B.
Explanation: Chloral is produced by chlorinating acetaldehyde or ethanol in an acidic solution by gradually increasing the temperature from 0 °C to 90…
Correct answer: Acetaldehyde.- A. Initiator
- B. Promoter
- C. Catalyst
- D. Reactant
Explanation: Explanation:In the conversion of ethylene into acetaldehyde, cupric chloride acts as promoter.
Correct answer: Promoter- A. Formaldehyde
- B. Acetaldehyde
- C. Calcium acetate
- D. Sodium acetate
Explanation: A is incorrect as formaldehyde is a product of calcium salt of formic acid.B is correct as Dry distillation of a mixture of the above…
Correct answer: Acetaldehyde- A. Ketone
- B. Aldehyde
- C. Formic Acid
- D. Ether
Explanation: Primary alcohols are oxidised to the corresponding aldehydes which are then oxidised to carboxylic acids.
Correct answer: AldehydePreparation of Aldehydes and Ketones MCQs: common questions
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