Question

Relative stability of the contributing structures is :

• A. \((I)>(III)>(II)\)
• B. \((I)>(II)>(III)\)
• C. \((II)>(I)>(III)\)
• D. \((III)>(II)>(I)\)

Answer 1

The Correct Option is B

The relative stability of the given contributing structures is determined by charge distribution, the number of covalent bonds, and adherence to the octet rule. Each structure is analyzed as follows:

1. Structure (I):
   • This structure is highly stable as all atoms are neutral and satisfy the octet rule.
   • Numerous covalent bonds contribute to increased stability through electron sharing.
2. Structure (II):
   • A negative charge resides on the carbon atom, which is relatively stable due to carbon's ability to bear a negative charge.
   • All atoms present satisfy the octet rule.
3. Structure (III):
   • A positive charge is located on an oxygen atom. This is less stable than a negative charge on carbon because oxygen's high electronegativity makes it prefer a negative charge.
   • Although the octet rule is satisfied, the charge distribution reduces stability.

Based on these factors, the relative stability is ordered as:

• Structure (I) exhibits the highest stability due to the absence of charges and complete octet satisfaction.
• Structure (II) is more stable than structure (III), as a negatively charged carbon is more stable than a positively charged oxygen.
• Structure (III) is the least stable due to the reasons previously stated.

Consequently, the order of stability is \((I) > (II) > (III)\).