NEET Chemistry: Coordination Compounds questions with solutions

Q1. What is the IUPAC name of \( K_{2}\left[P t C l_{6}\right] ? \)

1. Potassium hexachloro platinum
2. Potassium hexachloro platinum (IV)
3. Potassium hexa chloro platinate (IV)
4. Dipotassium hexa chloro platinum

Answer: Potassium hexa chloro platinate (IV)

In K2[PtCl6], the complex ion is [PtCl6]2-, so platinum is in the +4 oxidation state because six chloride ligands contribute -6 total and the ion has a -2 charge. An anionic metal complex uses the metal name ending in “-ate,” giving “platinate(IV).”

Q2. The structures of \( \left[N i(C O)_{4}\right] \) and \( \left[N i\left(\left(P h_{3}\right)_{3} P\right)_{2} C l_{2}\right] \) are:

1. square planar in both cases
2. tetrahedral and square planar respectively
3. tetrahedral in both cases
4. square planar and tetrahedral respectively

Answer: tetrahedral and square planar respectively

In [Ni(CO)4], nickel is in the zero oxidation state and is 4-coordinate, which commonly gives a tetrahedral geometry for d10 metal carbonyls. In [Ni((Ph3)3P)2Cl2], nickel is Ni(II) (d8), and strong-field phosphine ligands favor a square planar arrangement.

Q3. The IUPAC name of \( \left[\mathrm{Ni}\left(\mathrm{NH}_{3}\right)_{4}\right]\left[\mathrm{NiCl}_{4}\right] \) is :

1. tetrachloronickel (II)-tetraaminenickel (II)
2. tetramminenickel (II)-tetrachloronickel (II)
3. tetraamminenickel (II)-tetrachloronickelate (II)
4. tetrachloronickel (II)-tetraaminenickelate (0)

Answer: tetraamminenickel (II)-tetrachloronickelate (II)

In [Ni(NH3)4], NH3 is neutral, so Ni is +2 and the cation is tetraamminenickel(II). In [NiCl4], each Cl is -1, so Ni is +2 and because the complex is an anion, the metal name becomes nickelate: tetrachloronickelate(II).

Q4. Some salts, although containing two different metallic elements, give test for one of them in solution. Such salts are:

1. complex salt
2. double salt
3. normal salt
4. none of these

Answer: complex salt

Complex salts contain a complex ion that remains intact in aqueous solution, so only one of the metallic components is detected as a free ion. Double salts, in contrast, dissociate completely into all their ions in solution.

Q5. Actinides have higher tendency to form complexes than Lanthanides, due to

1. Higher charge and smaller size
2. Smaller charge and larger size
3. They are radioactive
4. They are electropositive

Answer: Higher charge and smaller size

Actinide ions generally have higher charge and smaller ionic radii than lanthanide ions, giving them greater charge density. This makes them more polarizing and better able to form complexes with ligands.

Q6. Select the correct order of ions with respect to their ionic radii.

1. \( Y^{3+}<L u^{3+}<E u^{3+}<L a^{3+} \)
2. \( L u^{3+}<Y^{3+}<E u^{3+}<L a^{3+} \)
3. \( L u^{3+}<E u^{3+}<L a^{3+}<Y^{3+} \)
4. \( L a^{3+}<E u^{3+}<L u^{3+}<Y^{3+} \)

Answer: \( Y^{3+}<L u^{3+}<E u^{3+}<L a^{3+} \)

Across the lanthanides, ionic radii decrease due to lanthanide contraction. Y3+ is smaller than the lanthanides listed, and among Lu3+, Eu3+, and La3+, the radius increases as contraction decreases, giving the stated order.

Q7. Potassium ferrocyanide is an example of

1. Complex salts
2. Normal salts
3. Double salts
4. Basic salts

Answer: Complex salts

Potassium ferrocyanide contains the complex ion [Fe(CN)6]4-, so it is classified as a complex salt. It does not simply dissociate into Fe2+ and CN- ions like an ordinary salt.

Q8. Urea reacts with water to form A which will decompose to form B. When passed through Cu2+ (aq), deep blue colour solution C is formed. What is the formula of C from the following?

1. [Cu(NH3)4]2+
2. Cu(OH)2
3. CuCO3 Cu(OH)2
4. CuSO4

Answer: [Cu(NH3)4]2+

Urea reacts with water to produce ammonia (NH3). Ammonia then reacts with Cu2+ ions to form the deep blue-colored complex [Cu(NH3)4]2+.

Q9. The addition of excess of aqueous HNO3 to a solution containing [Cu(NH3)4]^2+ produces:

1. Cu^+
2. [Cu(H2O)4]^2+
3. Cu(OH)
4. Cu(NO3)2

Answer: [Cu(H2O)4]^2+

Excess HNO3 provides H+ ions, which displace NH3 ligands from [Cu(NH3)4]^2+, forming [Cu(H2O)4]^2+ as the stable complex in aqueous solution.

Q10. The type of isomerism shown by the complex [CoCl2(en)2] is

1. Geometrical isomerism
2. Coordination isomerism
3. Linkage isomerism
4. Ionization isomerism

Answer: Geometrical isomerism

The complex [CoCl2(en)2] exhibits geometrical isomerism because the two bidentate ethylenediamine (en) ligands and two chloride ligands can arrange themselves in cis (adjacent) or trans (opposite) positions around the central cobalt ion.

Q11. The name of complex ion, [Fe(CN)6]3− is:

1. Ferricyanide
2. Ferrocyanide
3. Hexacyanoferrate (III)
4. Hexacyanoferrate (II)

Answer: Hexacyanoferrate (III)

The oxidation state of Fe in [Fe(CN)6]3− is +3, and the correct IUPAC name for the complex is Hexacyanoferrate (III).

Q12. The sum of coordination number and oxidation number of the metal M in the complex [M(en)2(C2O4)]Cl (where en is ethylenediamine) is:

1. 9
2. 6
3. 7
4. 8

Answer: 9

The coordination number of M is 6 (4 from two bidentate en ligands and 2 from the bidentate oxalate ligand). The oxidation number of M is +3, as the complex is neutral overall and Cl contributes -1. Thus, the sum is 6 + 3 = 9.

Q13. Hexacyanoiron (III) ion is:

1. Hexacyanoiron (III) ion
2. Hexacyanoferrate (III) ion
3. Tricyanoferate (III) ion
4. Hexacyanidoferrate (III) ion

Answer: Hexacyanidoferrate (III) ion

The correct IUPAC name for the complex ion [Fe(CN)6]3- is Hexacyanidoferrate (III) ion, as per the rules of nomenclature for coordination compounds.

Q14. Cobalt (III) chloride forms several octahedral complexes with ammonia. Which of the following will not give test of chloride ions with silver nitrate at 25°C?

1. CoCl3·4NH3
2. CoCl3·5NH3
3. CoCl3·6NH3
4. CoCl3·3NH3

Answer: CoCl3·6NH3

In CoCl3·6NH3, all three chloride ions are coordinated to the cobalt ion, leaving no free chloride ions in solution to react with silver nitrate. Hence, it will not give a test for chloride ions.

Q15. Number of possible isomers for the complex [Co(en)2Cl2]Cl will be (en = ethylenediamine):

1. 2
2. 1
3. 3
4. 4

Answer: 2

The complex [Co(en)2Cl2]Cl has two geometrical isomers: cis and trans. Ethylenediamine (en) is a bidentate ligand, and the arrangement of the two Cl ligands determines the isomerism.

Q16. The correct IUPAC name for [CrF2(en)2]Cl is:

1. Chlorodifluoridobis (ethylene diamine) chromium (III)
2. Chlorodifluoridoethylenediaminechromium (III) chloride
3. Difluoridobis (ethylene diamine) chromium (III) chloride
4. Difluorido (ethylene diamine) chromium (III) chloride

Answer: Difluoridobis (ethylene diamine) chromium (III) chloride

The correct IUPAC name is 'Difluoridobis(ethylene diamine)chromium(III) chloride'. The ligands are named in alphabetical order, and the oxidation state of chromium is +3, as determined by charge balance.

Q17. An excess of AgNO3 is added to 100 mL of a 0.01 M solution of dichlorotetraaquachromium (III) chloride. The number of moles of AgCl precipitated would be:

1. 0.002
2. 0.003
3. 0.01
4. 0.001

Answer: 0.003

Dichlorotetraaquachromium (III) chloride has the formula [Cr(H2O)4Cl2]Cl. It dissociates to give 1 Cl⁻ ion from the outer sphere and 2 Cl⁻ ions from the coordination sphere, totaling 3 Cl⁻ ions per molecule. For 0.01 M solution in 100 mL, moles of the compound = 0.01 × 0.1 = 0.001. Total moles of Cl⁻ = 0.001 × 3 = 0.003. Each Cl⁻ reacts with Ag⁺ to form AgCl, so 0.003 moles of AgCl precipitate.

Q18. The complexes [Co(NH3)6]3+, [Cr(CN)6]3− and [Cr(NH3)6]3+ [Co(CN)6]3− are examples of which type of isomerism?

1. Linkage isomerism
2. Ionization isomerism
3. Coordination isomerism
4. Geometrical isomerism

Answer: Coordination isomerism

The given complexes involve the exchange of ligands between the cationic and anionic coordination spheres, which is characteristic of coordination isomerism.

Q19. The complex, [Pt(Py)(NH3)BrCl] will have how many geometrical isomers?

1. 3
2. 4
3. 2
4. 2

Answer: 3

The complex [Pt(Py)(NH3)BrCl] is a square planar complex. It can have three geometrical isomers: cis-Py, NH3; cis-Br, Cl; and trans-Py, NH3. This is due to the different possible arrangements of ligands around the platinum center.

Q20. In a particular isomer of [Co(NH3)4Cl2]+, the Cl-Co-Cl angle is 90°, the isomer is known as:

1. Linkage isomer
2. Optical isomer
3. cis-isomer
4. Position isomer

Answer: cis-isomer

The Cl-Co-Cl angle being 90° indicates that the two chloride ligands are adjacent to each other, which is characteristic of the cis-isomer in coordination compounds.