I) The chemical formula of ethanol is C2H5OH.

i) The chemical formula of ethanol is $C_2H_5OH$.

ii) The correct option representing the fermentation of sugar for the production of ethanol is B.

$$C_6H_{12}O_6 \xrightarrow{Yeast} 2CH_3CH_2OH + 2CO_2$$

The equation shows glucose ($C_6H_{12}O_6$) being fermented by yeast to produce ethanol ($CH_3CH_2OH$ or $C_2H_5OH$) and carbon dioxide ($CO_2$).
The correct option is $\boxed{B}$.

iii) The correct option representing the production of ethanol by hydration of ethene is D.

$$C_2H_4 + H_2O \xrightarrow{conc. H_2SO_4, heat} CH_3CH_2OH$$

This reaction involves the addition of water to ethene ($C_2H_4$) in the presence of concentrated sulfuric acid and heat to form ethanol ($CH_3CH_2OH$ or $C_2H_5OH$).
The correct option is $\boxed{D}$.

iv) Two plants (fruits) that can serve as raw materials for ethanol production are:

• Grapes
• Sugarcane

v) Two uses of ethanol are:

• As a solvent in many chemical processes and products.
• As a fuel (biofuel) in internal combustion engines.

vi) Ethanol is referred to as grain alcohol because it can be produced through the fermentation of sugars derived from grains such as corn, wheat, barley, or rye.