Which product is formed when a ketone is reduced?

The correct answer is option 2. Secondary alcohol.

When a ketone is reduced, the product formed is a secondary alcohol. Ketones have the general structure \( \text{R}_2\text{CO} \), where R groups can be either alkyl or aryl groups.

Reduction of Ketones: When ketones are reduced (typically using reducing agents such as lithium aluminium hydride (\(\text{LiAlH}_4\)) or sodium borohydride (\(\text{NaBH}_4\))), the carbonyl group (\(\text{C=O}\)) is converted to a hydroxyl group (\(\text{-OH}\)). This reaction produces a secondary alcohol:

Here, the ketone \(((CH_3)_2\text{CO})\) is reduced to a secondary alcohol \((CH_3CH(OH)CH_3)\).

Types of Alcohols: 

Primary Alcohol: Formed from the reduction of aldehydes.

Secondary Alcohol: Formed from the reduction of ketones.

Tertiary Alcohol: Cannot be directly formed from the reduction of ketones as ketones are already at the secondary stage.

Quaternary Alcohol: Would require a different process, such as alkylation of secondary alcohols.

Conclusion: The reduction of a ketone leads to the formation of a secondary alcohol.