How many products are formed in Cross aldol condensation? 

4

The correct answer is option 4. 4.

In a cross aldol condensation, two different aldehydes or ketones are used, leading to the formation of multiple products due to the possible combinations of enolate ions and carbonyl compounds. 

Possible Products in Cross Aldol Condensation

1. Self-aldol products: Each carbonyl compound can react with itself to form a product. If we have two different carbonyl compounds, we will have two such products.

2. Cross-aldol products: Each carbonyl compound can react with the enolate ion formed from the other carbonyl compound. This gives two more products.

Cross aldol reaction gives 4 products. For instance, ethanal and propanone reacts to give the following four products:

Therefore, in a cross aldol condensation, a total of 4 different products are formed :4.