Question

Assertion :The degree of complex formation in actinides decreases in the order
$M^{4+}>{MO}_2^{2+}>M^{3+}>{MO}_2^{+}$ Reason: Actinides form complexes with $\pi$-bonding ligands such as alkyl phosphines and thioethers.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

The higher the charge on the metal ion, smaller is the ionic size and more is the complex-forming ability. Thus, the degree of complex formation decreases in the order:

$M^{4+}>{MO}_2^{2+}>M^{3+}>{MO}_2^{+}$

The higher tendency of complex formation of ${MO}_2^{2+}$ as compared to $M^{3+}$ is due to the high concentration of charge on metal atom $M$ in ${MO}_2^{2+}$.