List of top Chemistry Questions on Resonance

From the following, the least stable structure is:
(Assume standard resonance structures)
The functional group that shows negative resonance effect is:
How many compounds among the following compounds show inductive, mesomeric as well as hyperconjugation effects?
Compounds

Relative stability of the contributing structures is :
Relative stability

The difference in energy between the actual structure and the lowest energy resonance structure for the given compound is