The process used for the conversion of sugar into Ethanol is :

The correct answer is Option (4) → Fermentation

Fermentation is the slow breakdown of complex organic compounds into simpler ones by enzymes. Ethanol is made commercially this way from sugars (molasses, sugarcane, grapes). The enzyme invertase hydrolyses sucrose to glucose and fructose, and zymase, found in yeast, converts these into ethanol and carbon dioxide:

    \( \displaystyle \underset{\text{sucrose}}{\ce{C12H22O11}} + \ce{H2O} \xrightarrow{\text{invertase}} \underset{\text{glucose}}{\ce{C6H12O6}} + \underset{\text{fructose}}{\ce{C6H12O6}} \)

    \( \displaystyle \ce{C6H12O6} \xrightarrow{\text{zymase}} \ce{2C2H5OH + 2CO2} \)

Air is kept out during the process; if air gets in, the ethanol is oxidised further to ethanoic acid.

NCERT (2026-27 edition):
Ethanol – “Ethanol, C₂H₅OH, is obtained commercially by fermentation, the oldest method is from sugars. The sugar in molasses, sugarcane or fruits such as grapes is converted to glucose and fructose, (both of which have the formula C₆H₁₂O₆), in the presence of an enzyme, invertase. Glucose and fructose undergo fermentation in the presence of another enzyme, zymase, which is found in yeast.”