CBSE 12th Standard Chemistry Subject Coordination Compounds Chapter Case Study Questions 2021
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CBSE 12th Standard Chemistry Subject Coordination Compounds Case Study Questions 2021
12th Standard CBSE
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Reg.No. :
Chemistry
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Read the passage given below and answer the following questions:
Metal carbonyl is an example of coordination compounds in which carbon monoxide (CO) acts as ligand. These are also called homoleptic carbonyls. These compounds contain both \(\sigma\) and \(\pi\) character. Some carbonyls have metal-metal bonds. The reactivity of metal carbonyls is due to (i) the metal centre and (ii) the CO ligands. CO is capable of accepting an appreciable amount of electron density from the metal atom into their empty \(\pi\) or \(\pi\)* orbitals. These types ofligands are called \(\pi\)-accepter or \(\pi\)-acid ligands. These interactions increases the Δo value.
The following questions are multiple choice questions. Choose the most appropriate answer:
(i) What is the oxidation state of metal in [ Mn2(CO)10] ?(a) +1 (b) -1 (c) +2 (d) 0 (ii) Among the following metal carbonyls, the C - O bond order is lowest in
(a) \(\left[\mathrm{Mn}(\mathrm{CO})_{6}\right]^{+}\) (b) \(\left[\mathrm{Fe}(\mathrm{CO})_{5}\right]\) (c) \(\left[\mathrm{Cr}(\mathrm{CO})_{6}\right]\) (d) \(\left[\mathrm{V}(\mathrm{CO})_{6}\right]^{-}\) (iii) The oxidation state of cobalt in K [CO(CO)4] is
(a) +1 (b) +3 (c) -1 (d) 0 (iv) Structure of decacarbonyl manganese is
(a) trigonal bipyramidial (b) octahedral (c) tetrahedral (d) square pyramidal. -
Read the passage given below and answer the following questions:
Werner, a Swiss chemist in 1892 prepared and characterised a large number of coordination compounds and studied their physical and chemical behaviour. He proposed that, in coordination compounds, metals possess two types of valencies, viz. primary; valencies, which are normally ionisable and secondary valencies which are non-ionisable. In a series of compounds of cobalt (III) chloride with ammonia, it was found that some of the chloride ions could be precipitated as AgCI on adding excess of AgNO3 solution in cold, but some remained in solution. The number of ions furnished by a complex in a solution can be determined by precipitation reactions. The measurement of molar conductance of solutions of coordination compounds helps to estimate the number of ions furnished by the compound in solution.
In these questions (i-iv), a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.
The following questions are multiple choice questions. Choose the most appropriate answer:
(i) Assertion: The complex [Co(NH3)3CI3] does not give precipitate with silver nitrate solution.
Reason: The given complex is non-ionisable.
(ii) Assertion: The complex [Co(NH3)4Cl2]Cl gives precipitate corresponding to 2 mol of AgCl with AgNO3 solution.
Reason: It ionises as [Co(NH3)4Cl2]+ + Cl-
(iii) Assertion: 1 mol of [CrCl2CH2O)4]Cl· 2H2O will give 1mol of AgCl on treating with AgNO3.
Reason: Cl- ions satisfying secondary valanceis will not be precipitated.
(iv) Assertion: CoCl3·3NH3 is not conducting while CoCl3·5NH3 is conducting.
Reason: The complex of CoCl3·3NH3 is [ CoCl3(3NH3)3] while that of CoCl3·5NH3 is [CoCl3(3NH3)5]Cl2. -
Read the passage given below and answer the following questions:
Arrangement of ligands in order of their ability to cause splitting Δ is called spectrochemical series. Ligands which cause large splitting (large Δ ) are called strong field ligands while those which cause small splitting (small Δ) are called weak field ligands. When strong field ligands approach metal atomlion, the value of Δo is large, so that electrons are forced to get paired up in lower energy t2g orbitals. Hence, a low-spin complex is resulted from strong field ligand. When weak field ligands approach metal atom/ion, the value of Δo is small, so that electrons enter high energy eg orbitals rather than pairing in low energy t2g orbitals. Hence, a high-spin complex is resulted from weak field ligands. Strong field ligands have tendency to form inner orbital complexes by forcing the electrons to pair up. Whereas weak field ligands have tendency to form outer orbital complex because inner electrons generally do not pair up.
In these questions (i-iv), a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.
(i) Assertion: In tetrahedral coordination entity formation, the d orbital splitting is inverted and is smaller as compared to the octahedral field splitting.
Reason: Spectrochemical series is based on the absorption of light by complexes with different ligands.
(ii) Assertion: F- ion is a weak field ligand and forms outer orbital complex.
Reason: F- ion cannot force the electrons of dz2 and dx2- y2 orbitals of the inner shell to occupy dxy, dyz and dzx orbitals of the same shell.
(iii) Assertion: The crystal field model is successful in explaining the formation, structures, colour and magnetic properties of coordination compounds.
Reason: In spectrochemical series, ligands are arranged in a series of increasing field strength.
(iv) Assertion: NF3 is a weaker ligand than N(CH3)3.
Reason: NF3 ionizes to give F- ions in aqueous solution. -
Read the passage given below and answer the following questions:
Ligands are atoms or ions which can donate electrons to the central atoms. Ligands can be monodentate, bidentate or polydentate as well. Few ligands can coordinate with the central atom through more than one site, these are called ambidentate ligands. When a di- or polydentate ligand uses its two or more donor atoms to bind a single metal ion, it is said to be a chelating ligand.
In these questions (i-iv), a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.
(i) Assertion: Glycinate ion is an example of mono dentate ligand.
Reason: Glycinate contains Nand O as donor atoms
(ii) Assertion: Oxalate ion is a bidentate ligand.
Reason: Oxalate ion has two donor atoms
(iii) Assertion: A chelating ligand must possess two or more lone pairs at such a distance that it may form suitable strain free 5 and 6 membered rings with the metal ion.
Reason: H2N- NH2 is a chelating ligand.
(iv) Assertion: In Zeise's salt coordination number of Pt is five.
Reason: Ethene is a monodentate ligand. -
Read the passage given below and answer the following questions:
For understanding the structure and bonding in transition metal complexes, the magnetic properties are very helpful. Low spin complexes are generally diamagnetic because of pairing of electrons, whereas high spin complexes are usually paramagnetic because of presence of unpaired electrons. Larger the number of unpaired electrons, stronger will be the paramagnetism. However magnetic behaviour of a complex can be confirmed from magnetic moment measurement. Magnetic moment \(\mu=\sqrt{n(n+2)} \text { B.M. }\)where n = number of unpaired electrons. Greater the number of unpaired electrons, more will be the magnetic moment.
In these questions ( i-iv), a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.
(i) Assertion: Both [Cr(H2O)6]2+ and [FeH2O)6]2+ have same magnetic moment.
Reason: Number of unpaired electrons in Cr2+ and Fe2+ are same.
(ii) Assertion: [Fe(H2O)5NO]SO4 is paramagnetic.
Reason: The Fe in [Fe(H2O)5NO]SO4 has three unpaired electrons.
(iii) Assertion: [Co(en)3]3+ is paramagnetic.
Reason: It is an inner orbital complex.
(iv) Assertion: [Ni(CN)4]2- is diamagnetic complex.
Reason: It involves dsl hybridisation and there is no unpaired electron.
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CBSE 12th Standard Chemistry Subject Coordination Compounds Case Study Questions 2021 Answer Keys
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(i) (d): Oxidation state of Mn in [Mn2(CO)10] is zero.
(ii) (d): In \(\left[\mathrm{V}(\mathrm{CO})_{6}\right]^{-}\), the anionic carbonyl complex can delocalise more electron density to antibonding \(\pi\)-orbital (d\(\pi\)-p\(\pi\) back bonding) of CO and thus lowers the bond order.
(iii) (c): K[CO(CO)4]
+ 1 + (x) + 4(0) = 0 or x = -1
(iv) (d): Mn2(CO)10 is made up of two square pyramidal Mn(CO)5 units joined by Mn - Mn bond. -
(i) (a)
(ii) (d): [Co(NH3)4Cl2]Cl + AgNO3➝[Co(NH3)4Cl2]+ + AgCl ↓
Thus it gives precipitate of 1 mol of AgCl.
(iii) (a) : The Cl ions outside the coordination sphere can only be precipitated.
(iv) (a) -
(i) (b)
(ii) (a)
(iii) (b)
(iv) (c): Due to high electronegativity of F- atoms, the lone pair of N-atom in NF3 molecule cannot be ligated easily. Whereas in N(CH3)3' CH3 group is a electron releasing group, thus lone pair of N-atom in N(CH3)3 molecule can be ligated easily.
Except, nitrogen fluoride, all other halides hydrolyse in water. -
(i) (d): Glycinate ion is an example of bidentate ligand. It contains Nand O as donor atoms.
(ii) (a)
(iii) (c) : H2N - NH2 does not act as chelating ligand.
The coordination by hydrazine leads to a three member highly unstable strained ring and thus it does not act as chelating agent.
(iv) (d): In Zeises salt, coordination no. of Pt is 4. Ethylene is a mono dentate ligand. -
(i) (a): Spin only magnetic moment, \(\mu=\sqrt{n(n+2)} \text { B.M. }\) where n = number of unpaired electrons.
As the number of unpaired electrons in Cr2+ ([Ar ]3d4) and Fe2+([Ar]3d6) are same, hence [Cr(H2O)6]2+ and [Fe(H2O)6]2+ will have same magnetic moment.
(ii) (a): Fe+ : [Ar] 3d6 4s1
When the weak field ligand H2O and strong field ligand NO+ attack, the configuration changes as follows: Fe+ : [Ar] 3d7 4s°
ஃ Fe+ has 3 unpaired electrons.
In presence of strong ethylenediamine ligand the electrons get paired.
Thus inner orbital complex with no unpaired electrons.
(iv) (a)
