Question

Match the complexes in Column I with their properties listed in Column II.

Column I		Column II
(A)	$\left[Co\left(NH_{3}\right)_{4}\left(H_{2}O\right)_{2}\right]Cl_{2}$	(p)	geometrical isomers
(B)	$\left[Pt\left(NH_{3}\right)_{2}Cl_{2}\right]$	(q)	paramagnetic
(C)	$\left[Co\left(H_{2}O\right)_{5}Cl\right]Cl$	(r)	diamagnetic
(D)	$\left[Ni\left(H_{2}O\right)_{6}\right]Cl_{2}$	(s)	metal ion with$+2$ oxidation state

• A. $(A)-(p, q, s), (B)-(p, r, s), (C)-(q, s), (D)- (q, s)$
• B. $(A)-(p, q, ), (B)-(r, s), (C)-(q, s), (D)- (p, q, s)$
• C. $(A)-(p, q, ), (B)-(p), (C)-(q), (D)- (r)$
• D. $(A)-(q), (B)-(r), (C)-(p), (D)- (s)$

Answer 1

Answer: (A)

$(A) \to p, q, s ; (B) \to p, r, s ; (C) \to q, s ; (D) \to q, s$
In all the complexes, the oxidation state of central metal ion is $+2$. Any complex with molecular formula $MA_{2}B_{2}$ shows geometrical isomerism. Moreover, valence shell electron configuration of $Co^{2+}$ in $\left[Co\left(NH_{3}\right)_{4}\left(H_{2}O\right)_{2}\right]Cl_{2}, \left[Co\left(H_{2}O\right)_{5}Cl\right]Cl$ and $Ni^{2+}$ in $\left[Ni\left(H_{2}O\right)_{6}\right]Cl_{2}$ (all are attached to weak field ligands) suggest that there are unpaired electrons (paramagnetic) whereas $Pt^{2+}$ do not have any unpaired electrons, hence, it is diamagnetic.