Coordination Compounds Chapter-Wise Test 4

Correct answer Carries: 4.

Wrong Answer Carries: -1.

What is the coordination number of iron in \( \ce{[Fe(en)2Cl2]^+} \)?

Each ethane-1,2-diamine (en) is bidentate, contributing 2 donor atoms, and each \( \ce{Cl^-} \) is unidentate. In \( \ce{[Fe(en)2Cl2]^+} \), 2 en (4 atoms) + 2 \( \ce{Cl^-} \) = 6.

6
4
5
3
1

How many unpaired electrons are present in \( \ce{[Mn(H2O)6]^2+} \)? (Mn atomic number = 25)

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

3
5
1
0
2

Which complex contains a ligand that donates four electrons to the metal ion?

In \( \ce{[Co(en)2Cl2]^+} \), each en (ethane-1,2-diamine) is bidentate, donating 4 electrons (2 per N atom) to Co.

\( \ce{[Co(en)2Cl2]^+} \)
\( \ce{[Co(NH3)6]^3+} \)
\( \ce{[Ni(H2O)4]^2+} \)
\( \ce{[Fe(CN)6]^3-} \)
1

How many chloride ligands must be adjacent in the cis isomer of \( \ce{[Co(NH3)3Cl3]} \)?

In \( \ce{[Co(NH3)3Cl3]} \) (octahedral), the cis (facial) isomer has 3 \( \ce{Cl^-} \) on one face, all adjacent, forming a triangle (3 adjacent pairs).

2
3
1
0
2

The number of geometrical isomers for \( \ce{[Co(NH3)2Cl2(en)]^+} \) is:

This octahedral complex (\( \ce{[Ma2b2c2]} \)) with 2 \( \ce{NH3} \), 2 \( \ce{Cl^-} \), and 1 en (bidentate) has 3 geometrical isomers due to different arrangements of \( \ce{NH3} \) and \( \ce{Cl^-} \).

2
1
4
3
4

What is the primary valence of Co in \( \ce{[Co(NH3)4Cl2]NO3} \)?

Primary valence is the oxidation state. In \( \ce{[Co(NH3)4Cl2]NO3} \), \( \ce{[Co(NH3)4Cl2]^+} \) balances \( \ce{NO3^-} \). \( \ce{NH3} \) is neutral, 2 \( \ce{Cl^-} \) = -2, so Co is +3 (+3 - 2 = +1).

2
1
3
4
3

Which compound has the formula \( \ce{[Co(en)2Cl2]Cl} \)?

The IUPAC name dichloridobis(ethane-1,2-diamine)cobalt(III) chloride indicates 2 \( \ce{Cl^-} \) and 2 en ligands in the coordination sphere, with 1 \( \ce{Cl^-} \) as a counter ion, matching \( \ce{[Co(en)2Cl2]Cl} \).

Dichloridobis(ethane-1,2-diamine)cobalt(III) chloride
Dichloridotetraamminecobalt(III) chloride
Tetraamminedichloridocobalt(III) chloride
Bis(ethane-1,2-diamine)dichloridocobalt(II) chloride
1

Which complex exhibits ionization isomerism with \( \ce{[Co(NH3)5Br]SO4} \)?

\( \ce{[Co(NH3)5SO4]Br} \) and \( \ce{[Co(NH3)5Br]SO4} \) differ by swapping \( \ce{Br^-} \) and \( \ce{SO4^2-} \) between the coordination sphere and counter ion, showing ionization isomerism.

\( \ce{[Co(NH3)5Cl]SO4} \)
\( \ce{[Co(en)3]^3+} \)
\( \ce{[Co(NH3)6]Br3} \)
\( \ce{[Co(NH3)5SO4]Br} \)
4

Which complex can show geometrical isomerism?

\( \ce{[Co(NH3)3(H2O)3]^3+} \) (octahedral, \( \ce{[Ma3b3]} \)) has 3 \( \ce{NH3} \) and 3 \( \ce{H2O} \), allowing facial (fac) and meridional (mer) isomers.

\( \ce{[Co(NH3)6]^3+} \)
\( \ce{[Co(NH3)3(H2O)3]^3+} \)
\( \ce{[Ni(CO)4]} \)
\( \ce{[Fe(CN)6]^4-} \)
2

Which complex absorbs light in the visible region due to a d-d transition?

\( \ce{[Cr(H2O)6]^3+} \) (Cr\(^{3+}\), \( d^3 \)) in an octahedral field undergoes d-d transitions, absorbing visible light (violet color).

\( \ce{[Ni(CO)4]} \)
\( \ce{[Fe(CN)6]^4-} \)
\( \ce{[Cr(H2O)6]^3+} \)
\( \ce{[Co(NH3)6]^3+} \)
3

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