Question

Which of the following is/are true regarding resonance?

• A. It is a way of describing delocalized electrons within certain molecules or polyatomic ions where the bonding cannot be explicitly expressed by a single Lewis structure
• B. Due to resonance, the compounds become unstable by delocalisation of pi electrons
  
• C. The resonance effect is also called mesomeric effect
• D. All of the above

Answer 1

Answer: (A), (C)

The resonance effect is also called mesomeric effect

Resonance:
It is a way of describing delocalized electrons within certain molecules or polyatomic ions where the bonding cannot be explicitly expressed by a single Lewis structure.

Resonance leads to stability:
Due to resonance, the compounds achieve extraordinary stability by delocalisation of pi(π) electrons. An electron moves from one atom to another, during which it releases energy i.e. reduces energy of the whole system and the system becomes stable.

Resonance effect is a permanent electron displacement effect which is also called the mesomeric effect.

Hence, option (a) and (c) are correct.