Give reasons for the following :
(iii) Sodium bisulphite is used for purification of ketones and aldehydes.

Explanation

### Step-by-Step Solution

1. **Understanding Sodium Bisulfite**: Sodium bisulfite is a chemical compound with the formula NaHSO3. It is commonly used in organic chemistry for its ability to react with carbonyl compounds such as aldehydes and ketones.

2. **Reaction with Aldehydes and Ketones**: When sodium bisulfite is added to an aldehyde or ketone, it reacts to form a bisulfite adduct. For example, when acetaldehyde (CH3CHO) reacts with sodium bisulfite, it forms a white crystalline precipitate of the bisulfite adduct (CH3CH(OH)SO3Na).

3. **Formation of a Precipitate**: The reaction results in the formation of a solid precipitate, which is a characteristic of the bisulfite adduct. This precipitate can be easily separated from the reaction mixture by filtration.

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