MCQ Detailed View

Fermentation is one of the oldest biochemical processes used for the preparation of alcohol. In this process, sugars such as glucose and fructose are converted into ethanol and carbon dioxide with the help of enzymes produced by yeast. The overall reaction is:

C₆H₁₂O₆ (Glucose) → 2CH₃–CH₂–OH (Ethanol) + 2CO₂

This reaction takes place under anaerobic conditions, meaning it occurs in the absence of oxygen. The key product of this fermentation is ethanol (CH₃–CH₂–OH), which is the only alcohol in the given options that can be prepared by this method.

Looking at the options:

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  Methanol (CH₃OH): This is not obtained by fermentation. It is usually manufactured industrially by catalytic hydrogenation of carbon monoxide.

  
  


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  Propanol (C₃H₇OH): This alcohol is not produced by fermentation of sugars but is synthesized industrially.

  
  


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  Phenol (C₆H₅OH): This is an aromatic compound, not an aliphatic alcohol, and cannot be prepared through fermentation.

  
  


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  Ethanol (CH₃–CH₂–OH): This is the main product of fermentation and has been prepared this way for thousands of years in brewing and wine-making.

  
  

Ethanol obtained from fermentation is widely used in alcoholic beverages, as a solvent, in pharmaceutical formulations, and as a biofuel. The fermentation process is also the foundation of many industries, including brewing, winemaking, and distilling.

Thus, the correct answer is ethanol, because it is the only alcohol among the options that can be prepared by the natural fermentation of sugars.