CBSE Class 12 Chemistry Coordination Compounds Worksheet Set 04

Short Answer Type Questions

Question. (i) What is the IUPAC name of the complex \( [Ni(NH_3)_6]Cl_2 \)?
(ii) What is meant by chelate effect?
Answer: (i) Hexaamminenickel (II) Chloride.
(ii) Formation of stable complex with a polydentate ligand due to stronger bonding is known as chelate effect.
OR
Formation of stable complex with a polydentate ligand due to stronger bonding than the non chelate complexes is known as chelate effect.

Question. (i) Which of the following is more stable complex and why?
\( [Co(NH_3)_6]^{3+} \) and \( [Co(en)_3]^{3+} \).
(ii) How many ions are produced from the complex, \( [Co(NH_3)_6]Cl_2 \) in solution?
Answer: (i) \( [Co(en)_3]^{3+} \): Because (en) is a chelating ligand/bidentate ligand.
(ii) Three ions \( [Co(NH_3)_6]^{2+} \), \( 2Cl^- \)

Question. (i) Write the IUPAC name of the following coordination compound \( [NiCl_4]^{2-} \).
(ii) Write IUPAC name of the complex: \( [CoCl_2(en)_2]^{2+} \).
Answer: (i) Tetrachloridonickelate (II) ion.
(ii) Dichloridobis (ethane-1, 2-diamine) cobalt (III) ion.

Question. (i) Write IUPAC name of the complex: \( [Co(NH_3)_4Cl(NO_2)]^+ \).
(ii) Write the coordination number and oxidation state of Platinum in the complex \( [Pt(en)_2Cl_2] \).
Answer: (i) Tetraamminechloridonitrocobalt (III) ion.
(ii) Coordination Number = 6,
Oxidation State = +2

Question. (i) Why are low spin tetrahedral complexes not formed?
(ii) Low spin configuration are rarely observed in tetrahedral coordination entity formation. Explain.
Answer: (i) Orbital splitting energies are not sufficiently large for forcing pairing of electrons.
(ii) The orbital splitting energies, \( \Delta \) are not sufficiently large for forcing pairing of electrons in the tetrahedral coordination entity formation.

Question. (i) A coordination compound with molecular formula \( CrCl_3.4H_2O \) precipitates one mole of AgCl with \( AgNO_3 \) solution. Its molar conductivity is found to be equivalent to two ions. What is the structural formula and name of the compound?
(ii) On the basis of crystal field theory, write the electronic configuration of \( d^6 \) in terms of \( t_{2g} \) and \( e_g \) in an octahedral field when \( \Delta_0 < P \).
Answer: (i) \( [Cr(H_2O)_4Cl_2]Cl \)
Tetraaquadichloridochromium (III) chloride.
(ii) \( t_{2g}^3 e_g^3 \).

Question. Using IUPAC norms write the formulae for the following:
(i) Sodium dicyanidoaurate (I)
(ii) Tetraamminechloridonitrito-N-platinum (IV) sulphate
Answer: (i) \( Na[Au(CN)_2] \)
(ii) \( [Pt(NH_3)_4Cl(NO_2)]SO_4 \)

Question. Using IUPAC norms write the formulae for the following:
(i) Tris(ethane-1,2-diamine)chromium(III) chloride
(ii) Potassium tetrahydroxozincate(II)
Answer: (i) \( [Cr(en)_3]Cl_3 \)
(ii) \( K_2[Zn(OH)_4] \)

Question. Using IUPAC norms write the formulae for the following:
(i) Potassium trioxalatoaluminate (III)
(ii) Dichloridobis(ethane-1,2-diamine)cobalt(III)
Answer: (i) \( K_3[Al(C_2O_4)_3] \)
(ii) \( [CoCl_2(en)_2]^+ \)

Question. (i) Write the formula for the following:
Tetraammineaquachloridocobalt (III) nitrate
(ii) Write the formula for the following:
Diamminechloridonitrito-N-platinum(II)
Answer: (i) \( [Co(NH_3)_4(H_2O)Cl](NO_3)_2 \)
(ii) \( [Pt(NH_3)_2Cl(NO_2)] \)

Question. (i) Write the IUPAC name of the following complex:
\( [Co(NH_3)_4Cl(NO_2)]Cl \)
(ii) Write the formula for the following:
Dichloridobis(ethane-1,2-diamine)cobalt(III) chloride
Answer: (i) Tetraamminechloridonitrito-N-cobalt (III) chloride.
(ii) \( [CoCl_2(en)_2]Cl \)

Question. (i) Write down the IUPAC name of the following complex:
\( [Cr(NH_3)_2Cl_2(en)_2]Cl \) (\( en = \text{ethylenediamine} \))
(ii) Write the formula for the following complex:
Pentaamminenitrito-O-Cobalt (III).
Answer: (i) Diamminedichloridobisethylenediaminechromium (III) chloride
(ii) \( [Co(NH_3)_5(ONO)]^{2+} \)

Question. (i) Write down the IUPAC name of the following complex: \( [Co(NH_3)_5Cl]^{2+} \)
(ii) Write the formula for the following complex:
Potassium tetrachloridonickelate (II)
Answer: (i) Pentaamminechloridocobalt (III) ion
(ii) \( K_2[NiCl_4] \)

Question. Using IUPAC norms write the formulae for the following:
(i) Hexaamminecobalt(III) sulphate
(ii) Potassium trioxalatochromate(III)
Answer: (i) \( [Co(NH_3)_6]_2(SO_4)_3 \)
(ii) \( K_3[Cr(C_2O_4)_3] \)

Question. Define the following terms with a suitable example of each:
(a) Polydentate ligand
(b) Homoleptic complex
Answer: (i) A ligand having several donor atoms. Example- EDTA.
(ii) A complex in which a metal is bound to only one kind of donor groups / ligands. Example- \( [Co(NH_3)_6]^{3+} \). (or any other correct example)
Detailed Answer:
(a) A ligand which contains several donor atoms in a single ligand is known as polydentate ligand. Example, \( N(CH_2CH_2NH_2)_3 \).
(b) Complexes in which a metal is bound to only one kind of donor groups are known as homoleptic complexes. Example, \( [Co(NH_3)_6]^{3+} \).

Question. Using IUPAC norms, write the formulae for the following complexes:
(a) Potassium tri(oxalato)chromate(III)
(b) Hexaaquamanganese(II) sulphate
Answer: (i) \( K_3[Cr(C_2O_4)_3] \)
(ii) \( [Mn(H_2O)_6]SO_4 \)

Question. Using IUPAC norms write the formulae for the following:
(i) Pentaammine nitrito-o-cobalt (III) Chloride
(ii) Potassium tetracyanonickelate (II)
Answer: (i) \( [Co(NH_3)_5ONO]Cl_2 \)
(ii) \( K_2[Ni(CN)_4] \)

Question. Using IUPAC norms, write the formulae for the following complexes:
(a) Hexaaquachromium(III) chloride
(b) Sodium trioxalatoferrate(III)
Answer: (a) \( [Cr(H_2O)_6]Cl_3 \)
(b) \( Na_3[Fe(ox)_3] \)

Question. Out of \( [CoF_6]^{3-} \) and \( [Co(en)_3]^{3+} \), which one complex is,
(i) Paramagnetic,
(ii) More stable,
(iii) Inner orbital complex and
(iv) High spin complex
(Atomic number of Co = 27)
Answer:
(i) \( [CoF_6]^{3-} \)
(ii) \( [Co(en)_3]^{3+} \)
(iii) \( [Co(en)_3]^{3+} \)
(iv) \( [CoF_6]^{3-} \)

Question. Define the following terms with a suitable example of each:
(a) Chelate complex
(b) Ambidentate ligand
Answer: (a) A complex formed by bi or polydentate ligands with metal. Example- \( [Co(en)_3]^{3+} \).
(b) A ligand which can ligate through two different donor atoms. Example-\( SCN^- \).
Detailed Answer:
(a) Chelate complex is the complex formed when a di- or polydentate ligand uses its two or more donor atoms to bind a single metal atom.
(b) Ligand which can ligate through two different atoms is called ambidentate ligand.

Question. (a) Although both \( [NiCl_4]^{2-} \) and \( [Ni(CO)_4] \) have \( sp^3 \) hybridisation yet \( [NiCl_4]^{2-} \) is paramagnetic and \( [Ni(CO)_4] \) is diamagnetic. Give reason. (Atomic no. of Ni = 28)
(b) Write the electronic configuration of \( d^5 \) on the basis of crystal field theory when:
(i) \( \Delta_o < P \) and (ii) \( \Delta_o > P \)
Answer: (a) In \( [NiCl_4]^{2-} \), \( Cl^- \) is a weak field ligand due to which there are two unpaired electrons in \( 3d \) orbital whereas in \( [Ni(CN)_4]^{2-} \), \( CN^- \) is a strong field ligand due to which pairing leads to no unpaired electron in \( 3d \)- orbital / or structural representation.
(b) (i) \( t_{2g}^3 e_g^2 \)
(ii) \( t_{2g}^5 e_g^0 \)
Detailed Answer:
(a) In \( [NiCl_4]^{2-} \) Ni is in +2 oxidation state and each \( Cl^- \) donates a pair of electron. So, \( Cl^- \) acts as a weak ligand and does not cause any forced pairing. Thus, electrons remains unpaired making it paramagnetic.
In \( [Ni(CO)_4] \), Ni is in zero oxidation state and CO acts as a strong ligand causing forced pairing. Thus, no electron remains unpaired making it diamagnetic.

Question. (i) Using crystal field theory, write the electronic configuration of iron ion in the following complex ion. Also predict its magnetic behaviour:
\( [Fe(H_2O)_6]^{2+} \)
(ii) Write the IUPAC name of the coordination complex: \( [CoCl_2(en)_2]NO_3 \)
Answer: (i) \( t_{2g}^4 e_g^2 \), Paramagnetic
(ii) Dichloridobis(ethane-1,2-diamine)cobalt(III) nitrate

Question. (i) Predict the geometry of \( [Ni(CN)_4]^{2-} \).
(ii) Calculate the spin only magnetic moment of \( [Cu(NH_3)_4]^{2+} \) ion.
Answer: (i) Square planar.
(ii) In \( Cu^{2+} \), electronic configuration (\( 3d^9 \)) has one unpaired electron so, magnetic moment
\( = \sqrt{n(n+2)} = \sqrt{1(1+2)} = \sqrt{3} = 1.73 \text{ BM} \)

Short Answer Type Questions-

Question. Write the IUPAC name of the following:
(i) \( [Co(NH_3)_6]Cl_3 \)
(ii) \( [NiCl_4]^{2-} \)
(iii) \( K_3[Fe(CN)_6] \)
Answer: (i) Hexaamminecobalt (III) chloride.
(ii) Tetrachloridonickelate (II) ion.
(iii) Potassiumhexacyanoferrate (III)

Question. (i) For the complex \( [Fe(CN)_6]^{3-} \), write the hybridisation, magnetic character and spin nature of the complex. (At. number: Fe = 26).
(ii) Give the limitations of valence bond theory.
Answer: (i) Hybridization: \( d^2sp^3 \)
Magnetic character: Paramagnetic
Spin nature of the complex: Low spin.
(ii) (a) No explanation for magnetic properties of complex compound.
(b) No explanation for absorption spectra, difference between square planar and tetrahedral in nature.
(c) Failed to distinct between strong and weak field ligands.
 

Question. Write the hybridisation, shape and magnetic character of \( [Fe(CN)_6]^{4-} \).
Answer: Hybridisation: \( d^2sp^3 \)
Shape: Octahedral
Magnetic character: Diamagnetic

Question. (a) What type of isomerism is shown by the complex \( [Co(NH_3)_5(SCN)]^{2+} \)?
(b) Why is \( [NiCl_4]^{2-} \) paramagnetic while \( [Ni(CN)_4]^{2-} \) is diamagnetic ? (Atomic number of Ni = 28)
(c) Why are low spin tetrahedral complexes rarely observed?
Answer: (a) Linkage isomerism.
(b) In \( [NiCl_4]^{2-} \), due to the presence of \( Cl^- \), a weak field ligand no pairing occurs whereas in \( [Ni(CN)_4]^{2-} \), \( CN^- \) is a strong field ligand and pairing takes place.
(c) Because of very low CFSE which is not able to pair up the electrons.

Question. For the complex ion \( [CoF_6]^{3-} \) write the hybridisation type, magnetic character and spin nature. [Atomic number: Co = 27]
Answer: Hybridisation: \( sp^3d^2 \)
Magnetic character: Paramagnetic
Spin nature: High spin

Question. For the complex ion \( [Ni(CN)_4]^{2-} \) write the hybridisation type, magnetic character and spin nature. [Atomic number: Ni = 28]
Answer: Hybridisation: \( dsp^2 \)
Magnetic character: Diamagnetic
Spin nature: Low spin

Question. A metal complex having composition \( Cr(NH_3)_4Cl_2Br \) has been isolated in two forms A and B. The form A reacts with \( AgNO_3 \) to give a white precipitate readily soluble in dilute aqueous ammonia whereas B gives a pale yellow precipitate soluble in concentrated ammonia.
(i) State the hybridisation of chromium in each of them.
(ii) Calculate the magnetic moment (spin only value) of the isomer A.
Answer: (i) Isomer A: \( [Cr(NH_3)_4BrCl]Cl \)
Isomer B: \( [Cr(NH_3)_4Cl_2]Br \)
(ii) Hybridisation of Cr in isomer A and B is \( d^2sp^3 \).
Number of unpaired electrons in \( Cr^{3+} \)(\( 3d^3 \)) is 3
Magnetic moment \( = \sqrt{n(n+2)} \)
\( = \sqrt{3(3+2)} \)
\( = 3.87 \text{ BM} \)

Question. Write IUPAC name for each of the following complexes:
(i) \( [Ni(NH_3)_6]Cl_2 \)
(ii) \( K_3[Fe(CN)_6] \)
(iii) \( [Co(en)_3]^{3+} \)
Answer: (i) Hexaamminenickel (II) chloride
(ii) Potassium hexacyanidoferrate (III)
(iii) Tris(ethane-1,2-diamine)cobalt (III) ion

Question. (a) Write the formula of the following coordination compound:
Iron(III) hexacyanoferrate(II)
(b) What type of isomerism is exhibited by the complex \( [Co(NH_3)_5Cl]SO_4 \)?
(c) Write the hybridisation and number of unpaired electrons in the complex \( [CoF_6]^{3-} \).
(Atomic No. of Co = 27)
Answer: (a) \( Fe_4[Fe(CN)_6]_3 \)
(b) Ionisation isomerism
(c) \( sp^3d^2 \), octahedral complex with 4 unpaired electrons

Question. A metal complex having composition \( Cr(NH_3)_4Cl_2Br \) has been isolated in two forms A and B. The form A reacts with \( AgNO_3 \) to give a white precipitate readily soluble in dilute aqueous ammonia whereas B gives a pale yellow precipitate soluble in concentrated ammonia.
(i) State the hybridisation of chromium in each of them.
(ii) Calculate the magnetic moment (spin only value) of the isomer A.
Answer: (i) Hybridisation of Cr in isomer A and B is \( d^2sp^3 \).
(ii) Number of unpaired electrons in \( Cr^{3+} \)(\( 3d^3 \)) is 3
Magnetic moment \( = \sqrt{n(n+2)} \)
\( = \sqrt{3(3+2)} \)
\( = 3.87 \text{ BM} \)

Question. (i) What type of isomerism is shown by the complex \( [Cr(H_2O)_6]Cl_3 \)?
(ii) On the basis of crystal field theory, write the electronic configuration for \( d^4 \) ion if \( \Delta_o > P \).
(iii) Write the hybridization and shape of \( [CoF_6]^{3-} \).
(Atomic number of Co = 27)
Answer: (i) Hydrate isomerism
(ii) Electronic configuration is \( t_{2g}^4 e_g^0 \) or by diagram.
(iii) Hybridisation is \( sp^3d^2 \) and shape is octahedral.

Question. (i) Define crystal field splitting energy. On the basis of crystal field theory, write the electronic configuration for \( d^4 \) ion if \( \Delta_o < P \).
(ii) \( [Ni(CN)_4]^{2-} \) is colourless whereas \( [Ni(H_2O)_6]^{2+} \) is green. Why? (At. no. of Ni = 28)
Answer: (i) It is the magnitude of difference in energy between the two sets of \( d \) orbital i.e., \( t_{2g} \) and \( e_g \)
\( t_{2g}^3 e_g^1 \)
(ii) In \( [Ni(H_2O)_6]^{2+} \), \( Ni^{+2}(3d^8) \) has two unpaired electrons which do not pair up in the presence of weak field ligand \( H_2O \).
Detailed Answer:
(i) The difference in energy between the two sets of \( d \)-orbital (\( t_{2g} \) and \( e_g \)) caused by splitting of the degenerate levels due to the presence of ligands in a definite geometry.
Electronic configuration: \( t_{2g}^3 e_g^1 \)
(ii) In \( [Ni(H_2O)_6]^{2+} \), Ni is present in +2 state with the configuration \( 3d^8 \). It has two unpaired electrons which do not pair up in the presence of the weak \( H_2O \) ligand. Therefore, it is green in colour. While undergoing \( d-d \) transition, red light is absorbed and complementary light emitted is green.
In case of \( [Ni(CN)_4]^{2-} \), Ni is in +2 state with the configuration \( 3d^8 \) but in presence of the strong \( CN^- \) ligand, the two unpaired electrons in the \( 3d \) orbitals undergoes pairing. As there is no unpaired electron present, it is colourless.

Question. (i) Define crystal field splitting energy. On the basis of crystal field theory, write the electronic configuration for \( d^4 \) ion if \( \Delta_o > P \).
(ii) \( [Ni(CN)_4]^{2-} \) is diamagnetic whereas \( [NiCl_4]^{2-} \) is paramagnetic. Give reason. (At. no. of Ni = 28)
Answer: (i) It is the magnitude of difference in energy between the two sets of \( d \) orbital i.e. \( t_{2g} \) and \( e_g \)
\( t_{2g}^4 e_g^0 \).
(ii) In \( [Ni(CN)_4]^{2-} \), \( CN^- \) is a strong field ligand and pairing takes place whereas in \( [NiCl_4]^{2-} \), due to the presence of \( Cl^- \), a weak field ligand no pairing occurs/diagrammatic representation.

Question. A metal ion \( Mn^{n+} \) having \( d^4 \) valence electronic configuration combines with three bidentate ligands to form a complex compound. Assuming \( \Delta_o > P \).
(i) Write the electronic configuration of \( d^4 \) ion.
(ii) What type of hybridisation will \( Mn^{n+} \) ion has?
(iii) Name the type of isomerism exhibited by this complex.
Answer: (i) \( t_{2g}^4 e_g^0 \)
(ii) \( sp^3d^2 \)
(iii) Optical isomerism

Question. (a) Write the formula of the following coordination compound: Iron(III) hexacyanoferrate(II)
(b) What type of isomerism is exhibited by the complex \( [Co(NH_3)_5Cl]SO_4 \)?
(c) Write the hybridisation and number of unpaired electrons in the complex \( [CoF_6]^{3-} \). (Atomic No. of Co = 27)
Answer: (a) \( Fe_4[Fe(CN)_6]_3 \)
(b) Ionisation isomerism
(c) \( sp^3d^2 \), 4