Question

1. Which of the following statements regarding resonance is true?

   1. The true form of the compound is an average of the resonance structures called the resonance hybrid.

   2. all resonance structures must contribute equally to the resonance hybrid.

   3. Resonance structures interconvert over time.

   4. Atom connectivity must remain the same among resonance structures.

   5. There cannot be more than two resonance structures for a given compound

   		3, 4 & 5
   		1, 3 & 4
   		2, 3 & 5
   		All of the choices
   		1 & 4

Answer 1

For1, resonance hybrid only exists in real which is the most stable structure and defines all the properties. So it is true.

For2, different resonnace structures contribute differently, the structure whuch is more stable contribute more to the resonance hybrid. So this is false.

For3, resonance structures donot exist in real, the are imaginary so they xant interconvert,therefore it is false.

For4, atom connectivity must remains same in resonnace structure, resonance is nothing but a different way to draw a lewis structure of compound following octet rule. So this is true.

For5, there can be as many resonance structures for a compound, more is the conjugation, more is the number of resonance structures. So this is false.

Hence, 1 and 4 are true.