Coordination Compounds Chapter-Wise Test 7

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which complex has a secondary valence of 6 according to Werner’s theory?

Secondary valence is the coordination number. \( \ce{[Fe(H2O)6]^3+} \) has 6 \( \ce{H2O} \) ligands, giving a coordination number of 6.

\( \ce{[Fe(H2O)6]^3+} \)
\( \ce{[NiCl4]^2-} \)
\( \ce{[Cu(NH3)4]^2+} \)
\( \ce{[PtCl2(NH3)2]} \)
1

In which complex does the metal ion have an oxidation state twice the number of bidentate ligands?

In \( \ce{[Ni(en)2]^2+} \), Ni is +2, with 2 bidentate en ligands. Oxidation state (2) = 2 × number of bidentate ligands (1).

\( \ce{[Ni(en)2]^2+} \)
\( \ce{[Co(en)3]^3+} \)
\( \ce{[Cr(en)3]^3+} \)
\( \ce{[Fe(en)2Cl2]^+} \)
1

Which ligand causes the smallest crystal field splitting in an octahedral field?

From the spectrochemical series (\( \ce{F^-} < \ce{H2O} < \ce{NH3} < \ce{CN^-} \)), \( \ce{F^-} \) is the weakest field ligand, causing the smallest \( \Delta_o \).

\( \ce{NH3} \)
\( \ce{H2O} \)
\( \ce{F^-} \)
\( \ce{CN^-} \)
3

How many ionizable ions are produced when \( \ce{[Co(NH3)5Br]SO4} \) is dissolved in water?

In \( \ce{[Co(NH3)5Br]SO4} \), the complex \( \ce{[Co(NH3)5Br]^+} \) and \( \ce{SO4^2-} \) dissociate into 2 ions. The \( \ce{Br^-} \) inside is a ligand, not ionizable.

2
3
1
4
1

Which pair represents coordination isomerism?

\( \ce{[Co(NH3)6][Fe(CN)6]} \) and \( \ce{[Fe(NH3)6][Co(CN)6]} \) swap ligands between coordination spheres, showing coordination isomerism.

\( \ce{[Co(NH3)5Cl]^2+} \) and \( \ce{[Co(NH3)5NO2]^2+} \)
\( \ce{[Co(NH3)4Cl2]^+} \) (cis and trans)
\( \ce{[Co(NH3)5SO4]Br} \) and \( \ce{[Co(NH3)5Br]SO4} \)
\( \ce{[Co(NH3)6][Fe(CN)6]} \) and \( \ce{[Fe(NH3)6][Co(CN)6]} \)
4

Which complex aligns with Werner’s theory by having a primary valence of 2?

Primary valence is the oxidation state. In \( \ce{[Ni(H2O)6]Cl2} \), Ni is +2 (balancing 2 \( \ce{Cl^-} \)), consistent with Werner’s theory.

\( \ce{[Ni(H2O)6]Cl2} \)
\( \ce{[Co(NH3)6]Cl3} \)
\( \ce{[Fe(CN)6]^3-} \)
\( \ce{[PtCl6]^2-} \)
1

How many electrons are in the \( e_g \) orbitals of \( \ce{[Fe(H2O)6]^3+} \) with Fe in the +3 state? (Fe atomic number = 26)

Fe\(^{3+}\) (\( d^5 \)) in \( \ce{[Fe(H2O)6]^3+} \) (octahedral) with weak field \( \ce{H2O} \) is high spin: \( t_{2g}^3 e_g^2 \), so 2 electrons in \( e_g \).

1
2
3
0
2

Which complex follows Werner’s coordination theory by having a primary valence of 3?

Primary valence is the oxidation state. In \( \ce{[Co(NH3)6]Cl3} \), Co is +3 (balancing 3 \( \ce{Cl^-} \)), satisfying Werner’s theory with ionizable counter ions.

\( \ce{[Co(NH3)6]Cl3} \)
\( \ce{[Ni(NH3)4]^2+} \)
\( \ce{[Cu(NH3)4]^2+} \)
\( \ce{[Fe(CN)6]^4-} \)
1

Which complex produces 3 ions in aqueous solution, including the coordination sphere?

\( \ce{[Ni(NH3)4]Cl2} \) dissociates into \( \ce{[Ni(NH3)4]^2+} \) (1 ion) and 2 \( \ce{Cl^-} \) (2 ions), totaling 3 ions.

\( \ce{[Ni(NH3)4]Cl2} \)
\( \ce{[Co(NH3)6]Cl3} \)
\( \ce{[Fe(H2O)5Cl]Cl} \)
\( \ce{[Cr(en)3]^3+} \)
1

What is the oxidation state of iron in \( \ce{[Fe(H2O)5NO]^2+} \)?

In \( \ce{[Fe(H2O)5NO]^2+} \), \( \ce{H2O} \) is neutral, and \( \ce{NO} \) is typically \( \ce{NO^+} \) (nitrosyl, +1) in such complexes. The overall charge is +2. Thus, \( x + 0 + 1 = +2 \), so \( x = +1 \) for Fe.

+1
+2
+3
+4
1

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