Sucrose is converted to glucose and fructose in the presence of an enzyme, invertase or sucrase. Glucose and fructose undergo fermentation in the presence of another enzyme, zymase. Both these enzymes are present in yeast.

$\underset{\text { Sucrose }}{\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}}+\mathrm{H}_2 \mathrm{O} \xrightarrow{\text { Invertase/sucrose }} \underset{\text { Glucose }}{\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6}+\underset{\text { Fructose }}{\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6}$

$\underset{\substack{\text { Glucose /Fructose }}}{\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6} \xrightarrow{\text { Zymase }} \underset{\substack{\text { Ethanol }}}{2 \mathrm{CH}_3 \mathrm{CH}_2 \mathrm{OH}}+2 \mathrm{CO}_2$

Propan-2-one is a ketone. Its structural formula is ketones when treated with Grignard reagent give tertiary alcohols.

Some compounds can rotate the plane polarised light, when it is passed through their solution. Such compounds are called optically active compounds. The structures of the isomers of alcohols with molecular formula $\mathrm{C}_4 \mathrm{H}_{10} \mathrm{O}$ are as follows

(i)	$\mathrm{CH}_3-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{OH}$	Butan-1-ol
(ii)		Butan-2-ol
(iii)		2-methylpropan-1-ol
(iv)		2-methylpropan-2-ol

The asymmetry of the molecule is responsible for the optical activity in a molecule. If all the four substituents attached to the carbon are different then the carbon is called asymmetric or chiral carbon and such a molecule is called asymmetric molecule. In the above explained structure, it is only butan-2-ol which contains a chiral carbon and hence it is optically active.

In phenols, the electron pairs on oxygen atom of -OH group are in conjugation (or resonance) with $\pi$ electrons of the ring and the following resonating structures are possible

Out of these five resonating structures, II, III and IV structures contain a carbon-oxygen double bond character. In other words, carbon-oxygen bond in phenol acquires a partial double bond character due to resonance. But in alcohols carbon-oxygen bond in alcohols is purely single bond. Therefore, -OH group in phenols is more strongly held as compared to - OH group in alcohols.

Resonance is an important factor in phenols. During resonance -OH group in phenol gives its electrons to the benzene ring. As a result of this, the electron density on benzene ring is very high. This increased electron density repels nucleophiles.

Therefore, nucleophiles cannot attack the benzene ring and phenols usually do not give nucleophilic substitution reaction.