When ethanal and propanal are treated with dil. $NaOH$ followed by heating number of (structural)$\alpha ,\beta$ Unsaturated carbonyl compounds formed are _____ 

Propanal on aldol condensation gives 2-methylpent-2-enal. From cross aldol condensation of Ethanal and Propanal,it forms 2products, one when ethanol acts as enolate ion and one where propanal acts as enolate ion. The two cross aldol products are- 2-methylbut-2-enal and Pent-2-enal.