After fermentation, the most extensive industrial use of molasses is for the production of which of the following substances?

Introduction / Context:
Molasses is a thick, dark syrup that remains after sugar crystallisation from sugarcane or sugar beet juice. It is rich in fermentable sugars and is an important raw material in industrial chemistry. This question focuses on what product is most extensively obtained from molasses after fermentation, highlighting the link between agricultural by products and useful chemicals.

Given Data / Assumptions:

• Molasses contains residual sugars suitable for fermentation by microorganisms.
• Fermentation typically uses yeast to convert sugars into other compounds.
• The question asks about the main industrial product obtained after fermentation of molasses.
• We assume standard industrial practice in the sugar and distillery industries.

Concept / Approach:
Fermentation of molasses by yeast (usually Saccharomyces species) converts the sugars present into ethanol and carbon dioxide. Ethanol produced from molasses is widely used as industrial alcohol, fuel ethanol, or for making beverages after proper processing. Methanol, on the other hand, is not obtained by this simple carbohydrate fermentation process but largely from synthesis gas in chemical industry. Sugar itself is extracted from sugarcane juice before molasses remains. Sugarcane is the original plant, not a product. Acetic acid can be produced by further oxidation of ethanol but is not the primary direct product of molasses fermentation.

Step-by-Step Solution:

Verification / Alternative check:
If we look at a simple fermentation reaction, glucose (as a representative sugar from molasses) is converted by yeast according to the approximate equation: C6H12O6 gives 2 C2H5OH plus 2 CO2. This shows that ethanol and carbon dioxide are the main products. Industrially, the ethanol is distilled and used in various applications. Textbooks on industrial chemistry explicitly mention molasses as a major raw material for ethanol production, confirming that ethanol is the main product.

Why Other Options Are Wrong:

• Methanol: Typically produced from synthesis gas (carbon monoxide and hydrogen), not by fermentation of molasses.
• Sugar: Already crystallised from the original juice; molasses is what remains after sugar is removed and is not fermented back into sugar.
• Sugarcane: This is the original plant and source of juice, not a product of molasses processing.
• Acetic acid: Can result from the oxidation of ethanol by bacteria, but it is not the primary direct product of molasses fermentation in distilleries.

Common Pitfalls:
Students may see terms like sugar and sugarcane and think that molasses is somehow converted back to these, but that is not correct. Another confusion is to mix methanol and ethanol because both are alcohols. However, their sources and manufacturing processes are different. Remember that molasses fermentation by yeast is a classic route to ethanol, sometimes called fermentation alcohol.

Final Answer:
After fermentation, the most extensive industrial use of molasses is for producing Ethanol.