Write the resonance structures of $CH_2=CH-CHO$. Indicate the relative stability of the contributing structures.

(N/A) The resonance structures for $CH_2=CH-CHO$ are:
$I$: $CH_2=CH-CH=O$
$II$: $^+CH_2-CH=CH-O^-$
$III$: $^-CH_2-CH=CH-O^+$
Relative stability: $I > II > III$
Explanation:
$I$: Most stable,as it has the maximum number of covalent bonds,all atoms have complete octets,and there is no charge separation.
$II$: More stable than $III$ because the negative charge is on the more electronegative oxygen atom and the positive charge is on the less electronegative carbon atom.
$III$: Least stable,as it involves charge separation with a positive charge on the highly electronegative oxygen atom and a negative charge on the carbon atom.