Question

Choose the correct sequence on the basis of number of unpaired electrons present in the given field:
A. $Cr(+II)$ in weak field
B. $Co(+II)$ in strong field
C. $Ni(+II)$ in strong field
D. $Pt(+II)$ in weak field
E. $Ag(+II)$ in strong field
Choose the correct answer from the options given below :

• A. C = D < B = E < A
• B. B = E < A < C = D
• C. B < C < D = A < E
• D. A < B < C < D = E

Hint:

Key exceptions to memorize: 4d (Pd, Ru, Ag) and 5d (Pt, Ir, Au) transition metals essentially never form high-spin complexes. Furthermore, $d^8$ metals in a strong field (like $Ni^{2+}$ with $CN^-$) or heavy $d^8$ metals (like $Pt^{2+}, Pd^{2+}$) predominantly form square planar complexes, which are completely diamagnetic (0 unpaired electrons).

Answer 1

The Correct Option is A