Question

what do you understand by resonance effect?

Answer 1

Definition– The resonance effect can be defined as a chemical phenomenon which is observed in the characteristic compounds having double bonds in the organic compounds. The organic compounds contain these double bonds in the structures and usually have the overlapping of the p-orbitals on the two adjacent sides of carbon atoms. 

Answer 2

according to resonance effect molecules are most stable .more resonance structure more stability of compound and more reactive.