Question

Question 29
Grapes hanging on the plant do not ferment but after being plucked from the plant can be fermented.

Under what conditions do these grapes ferment? Is it a chemical or a physical change?

Answer 1

Grapes, when attached to the plants, receive oxygen in their cells and undergo aerobic respiration. Whereas, fermentation occurs in the absence of oxygen i.e., in anaerobic conditions.

After grapes are plucked from plants, fermentation of sugar (present in the grapes) is carried out in the presence of yeast which converts the sugar to ethanol and carbon dioxide. This involves a chemical reaction, hence, it is a chemical change.