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:
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.
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.
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 \((I) > (II) > (III)\).
