Coordination Chemistry: A Comprehensive Guide to Metal Complexes

Question 1

Which of the following factors has no significant effect on the stability of metal complexes in solution?

Accepted Answer

Temperature

Answer

The size of the metal ion

Answer

The charge of the metal ion

Answer

The type of ligands bonded to the metal ion

Question 2

In coordination complexes, how do ligands interact with metal ions?

Accepted Answer

Ligands donate electron pairs to form coordinate bonds with the metal ion.

Answer

Ligands form only covalent bonds with metal ions.

Answer

The strength of a ligand depends solely on its charge.

Answer

Ligands do not affect the geometry of coordination complexes.

Question 3

How does the spectrochemical series affect the colors seen in transition metal complexes?

Accepted Answer

It determines the energy difference between d-orbitals, influencing the wavelengths of light absorbed and resulting in different colors.

Answer

It applies only to octahedral complexes.

Answer

It predicts the magnetic properties of coordination complexes.

Question 4

Determine the coordination number of the metal ion in the complex [Fe(en)2(H2O)2]Cl2.

Accepted Answer

6

Answer

4

Answer

5

Answer

8

Question 5

Which of the following ligands is considered a weak field ligand?

Accepted Answer

H2O

Answer

NH3

Answer

CN-

Answer

Cl-

Question 6

Which of the following is NOT a common coordination geometry for metal complexes?

Accepted Answer

Trigonal pyramid

Answer

Tetrahedral

Answer

Square planar

Answer

Trigonal bipyramidal

Question 7

What is the fundamental difference between a chelating ligand and a monodentate ligand?

Accepted Answer

Chelating ligands can form multiple bonds with the metal ion, while monodentate ligands form only one.

Answer

Chelating ligands are always larger than monodentate ligands.

Answer

Chelating ligands are inherently stronger than monodentate ligands.

Answer

There is no fundamental difference between chelating ligands and monodentate ligands.

Question 8

Which of the following ligands is a strong-field ligand?

Accepted Answer

CN-

Answer

Cl-

Answer

NH3

Answer

H2O

Question 9

Determine the coordination number of the metal ion in [PtCl6]2-?

Accepted Answer

6

Answer

4

Answer

8

Answer

10

Question 10

In coordination chemistry, what is the term for the molecule or ion that donates electrons to the metal ion?

Accepted Answer

Ligand

Answer

Chelate

Answer

Complex

Answer

Counterion

Question 11

For a complex containing a metal ion directly bonded to three ligands, what is its coordination number?

Accepted Answer

3

Answer

2

Answer

4

Answer

6

Question 12

In the coordination complex [Fe(NH3)6]Cl3, what is the oxidation state of the iron ion?

Accepted Answer

+3

Answer

+1

Answer

+2

Answer

+4

Question 13

Which of these complexes is predicted to be diamagnetic?

Accepted Answer

[Cr(H2O)6]3+

Answer

[Fe(CN)6]4-

Answer

[Ni(NH3)6]2+

Answer

[Cu(NH3)4]2+

Question 14

Name the theory that describes the bonding and properties of coordination complexes based on the hybridization of atomic orbitals of the metal ion.

Accepted Answer

Ligand field theory

Answer

Crystal field theory

Answer

Molecular orbital theory

Answer

Valence bond theory

Question 15

What is the region of a metal complex that includes the metal ion and its ligands?

Accepted Answer

Coordination sphere

Answer

Metal ion only

Answer

Ligands only

Answer

Metal ion and counterions

Question 16

What geometry is predicted for a square planar complex with four identical ligands?

Accepted Answer

Square planar

Answer

Tetrahedral

Answer

Octahedral

Answer

Trigonal bipyramidal

Question 17

Which types of isomerism are commonly observed in coordination complexes?

Accepted Answer

Both structural and stereoisomerism

Answer

Structural isomerism

Answer

Stereoisomerism

Answer

Electronic isomerism

Question 18

Which of the following is NOT a type of ligand?

Accepted Answer

Metal

Answer

Monodentate

Answer

Bidentate

Answer

Polydentate

Question 19

What is the coordination number of a metal ion in a complex?

Accepted Answer

The number of ligands directly bonded to the metal ion

Answer

The charge of the metal ion

Answer

The number of electrons in the d-orbitals of the metal ion

Answer

The radius of the metal ion

Question 20

Which of the following is a strong-field ligand that can cause high-spin complexes?

Accepted Answer

CN-

Answer

Cl-

Answer

H2O

Answer

NH3

Question 21

What is the geometry of a tetrahedral complex with four monodentate ligands?

Accepted Answer

Tetrahedral

Answer

Octahedral

Answer

Square planar

Answer

Trigonal bipyramidal

Question 22

What is the IUPAC name for the complex [Co(NH3)5Cl]Cl2?

Accepted Answer

Pentaamminechlorocobalt(III) chloride

Answer

Pentaamminechloro cobalt(II) chloride

Answer

Hexaamminecobalt(III) chloride

Answer

Hexaamminecobalt(II) chloride

Question 23

Which of the following is NOT a type of ligand?

Accepted Answer

Ion

Answer

Monodentate

Answer

Bidentate

Answer

Chelating

Question 24

What is the difference between a coordination sphere and a coordination complex?

Accepted Answer

The coordination complex includes all ligands, while the coordination sphere includes only the metal ion and directly bonded ligands.

Answer

The coordination sphere includes all ligands, while the coordination complex includes only the metal ion and weakly bound ligands

Answer

The coordination sphere is the same as the coordination complex

Answer

There is no difference between a coordination sphere and a coordination complex

Question 25

What is the role of hemoglobin in the body?

Accepted Answer

It transports oxygen in the blood

Answer

It regulates blood pH

Answer

It stores glucose

Answer

It fights infections

Question 26

In the complex [Fe(CN)6]4-, the coordination sphere of the metal ion is:

Accepted Answer

Octahedral

Answer

Square planar

Answer

Tetrahedral

Answer

Trigonal bipyramidal

Question 27

Which of the following ligands is capable of forming a chelate ring?

Accepted Answer

Ethylenediamine

Answer

Ammonia

Answer

Carbon monoxide

Answer

Water

Question 28

The oxidation state of the metal ion in the complex [Cr(H2O)6]3+ is:

Accepted Answer

+3

Answer

+2

Answer

+1

Answer

0

Question 29

Among the following coordination complexes, which one is diamagnetic?

Accepted Answer

[Zn(NH3)4]2+

Answer

[Fe(CN)6]4-

Answer

[Mn(H2O)6]2+

Answer

[Co(NH3)6]3+

Question 30

The bond formed between a metal ion and a ligand is referred to as a:

Accepted Answer

Coordinate bond

Answer

Ionic bond

Answer

Covalent bond

Question 31

Which of the following complexes exhibits both geometric and optical isomerism?

Accepted Answer

[Co(en)3]Cl3

Answer

[Ni(CO)4]

Answer

[Fe(CN)6]4-

Answer

[Pt(NH3)2Cl2]

Question 32

The color of a transition metal complex is mainly due to:

Accepted Answer

d-orbital splitting and electronic transitions

Answer

The presence of ligands

Answer

The size of the metal ion

Answer

The oxidation state of the metal ion

Question 33

The stability of a coordination complex is mainly influenced by:

Accepted Answer

The nature of the metal ion, the ligands, and the solvent

Answer

Only the nature of the metal ion

Answer

Only the nature of the solvent

Question 34

In the reaction [Fe(H2O)6]3+ + 6CN- → [Fe(CN)6]3- + 6H2O, the formation of the hexacyanoferrate(III) complex is favored by:

Accepted Answer

The strong field ligand CN-

Answer

The large size of the Fe3+ ion

Answer

The weak field ligand H2O

Answer

The high concentration of H2O

Question 35

Which of the following applications of coordination chemistry is INCORRECT?

Accepted Answer

Coordination complexes are used as food preservatives, but they are not used as catalysts in industrial processes.

Answer

Coordination complexes are used in analytical chemistry for the detection and quantification of metal ions.

Question 36

Which of the following defines a coordination complex?

Accepted Answer

A central metal ion bonded to ligands through coordinate bonds

Answer

A mixture of metal ions and ligands in solution

Answer

A compound with a metal ion surrounded only by anions

Answer

A complex with a high molecular weight

Question 37

In the complex ion [Co(NH3)5Cl]2+, what is the coordination number of the cobalt ion?

Accepted Answer

6

Answer

10

Answer

8

Answer

4

Question 38

Which of the following ligands is capable of forming more than one bond to a metal ion?

Accepted Answer

Ethylenediaminetetraacetate (EDTA)

Answer

Chloride ion (Cl-)

Answer

Ammonia (NH3)

Answer

Water (H2O)

Question 39

The complex ion [Ni(H2O)6]2+ is green, while [Ni(NH3)6]2+ is blue. This difference in color is primarily attributed to:

Accepted Answer

The change in the ligand field strength

Answer

The presence of unpaired electrons in one complex and not the other

Answer

The variation in coordination number

Answer

The difference in oxidation states of nickel

Question 40

Calculate the oxidation state of chromium in the complex ion [Cr(CO)6]

Accepted Answer

0

Answer

+2

Answer

-2

Answer

+6

Question 41

Coordination compounds exhibit isomerism, which includes:

Accepted Answer

Both geometric and optical isomerism

Answer

Only geometric isomerism

Answer

Neither geometric nor optical isomerism

Answer

Only optical isomerism

Question 42

The formation constant (Kf) for a coordination complex is a measure of:

Accepted Answer

The equilibrium constant for the formation of the complex

Answer

The rate of formation of the complex

Answer

The solubility of the complex in a solvent

Question 43

Which factor has little to no influence on the stability of a coordination complex?

Accepted Answer

The electronegativity of the metal ion

Answer

The geometry of the complex

Answer

The nature of the ligands

Answer

The size and charge of the metal ion

Question 44

Which of the following is NOT a defining characteristic of coordination compounds?

Accepted Answer

They are always ionic in nature.

Answer

They contain a central metal atom or ion.

Answer

They can be neutral or ionic.

Answer

They involve coordination bonds between metal ions and ligands.

Question 45

What is the coordination number of the cobalt ion in the complex [Co(NH3)6]Cl3?

Accepted Answer

6

Answer

12

Answer

3

Answer

4

Question 46

Which of the following ligands is a bidentate ligand, meaning it binds to the metal ion through two donor atoms?

Accepted Answer

Ethylenediamine (en)

Answer

Water (H2O)

Answer

Ammonia (NH3)

Answer

Chloride ion (Cl-)

Question 47

A complex ion with a central metal ion surrounded by four ligands in a square planar arrangement is likely to have a coordination number of:

Accepted Answer

4

Answer

6

Answer

2

Question 48

Which of the following complexes is likely to exhibit the strongest crystal field splitting, meaning the largest energy difference between the d-orbitals?

Accepted Answer

[Co(CN)6]3-

Answer

[Co(H2O)6]3+

Answer

[Co(NH3)6]3+

Answer

[CoCl6]3-

Question 49

In a high-spin complex, how are the electrons in the d-orbitals distributed?

Accepted Answer

They are distributed among all the d-orbitals, maximizing the number of unpaired electrons.

Answer

They are paired up in the lower energy d-orbitals.

Answer

They are distributed only in the higher energy d-orbitals.

Question 50

Which of the following reactions is an example of a ligand substitution reaction, where one ligand is replaced by another?

Accepted Answer

[Cu(H2O)4]2+ + 4NH3 <=> [Cu(NH3)4]2+ + 4H2O

Answer

2H2 + O2 <=> 2H2O

Answer

Fe2+ + 6CN- <=> [Fe(CN)6]4-

Answer

Ag+ + Cl- <=> AgCl(s)

Question 51

Why do transition metal complexes often exhibit color?

Accepted Answer

The d-electrons in the metal ion absorb specific wavelengths of light during electronic transitions, causing the transmission or reflection of other wavelengths, which we perceive as color.

Answer

The scattering of light by the complex molecules.

Answer

The presence of ligands that are themselves colored.

Question 52

When a coordination compound acts as a catalyst, its primary function is to:

Accepted Answer

Lower the activation energy of the reaction, making it easier for the reaction to proceed.

Answer

Provide an alternate reaction pathway.

Answer

Increase the concentration of reactants.

Answer

Change the enthalpy change of the reaction.

Question 53

Which of the following is a significant application of coordination chemistry in the field of medicine?

Accepted Answer

Chemotherapy agents used in cancer treatment, which often target specific DNA sequences in cancer cells.

Answer

Water purification.

Answer

Dyeing of fabrics.

Answer

Production of fertilizers.