Consider the reaction,  Ethanal + Propanal  →ΔOH−products.  Product of the reaction cannot be

This is an example of crossed aldol condensation between two aldehydes containing α-Hydrogen atoms.Possible Products :1.                                           CH3−CH=O+H2CH−CHO→ΔOH−CH3−CH=CH−CHO+H2O2.3.4.                                               CH3CH2−CH=O+H2CH−CHO→ΔOH−CH3−CH2−CH=CH−CHO                                                   3 – Hexenal, CH3 – CH2 – CH = CH – CH2 – CHO can never be the product.