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All questions of Coordination Compounds for NEET Exam

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If zeise’s salt has the formula [Pt(C2H4)CI3]-. In this, platinum primary and secondary valency are
  • a)
    + 1 and 3
  • b)
    + 1 and 4
  • c)
    + 3 and 4
  • d)
    + 4 and 6
Correct answer is option 'B'. Can you explain this answer?

Krishna Iyer answered
Let the oxidation state of pt be x.
Oxidation state of cl is -1.
So x + 0 – (1*3) must be equal to -1 since the charge of the whole compound is -1.
x + 0 – (1*3) = -1
x -3 = -1
x = -1 + 3
x = +2
So the oxidation state of platinum is +2.
Secondary is due to legend there are mono deadened legend 
then 1×4= 4
 

The correct IUPAC name of the complex Fe(C5H5)2 is _
  • a)
    Cyclopentadienyl iron (II)
  • b)
    Bis (cyclopentadienyl) iron (II)
  • c)
    Dicyclopentadiency ferrate (II) 
  • d)
    Ferrocene
Correct answer is option 'B'. Can you explain this answer?

Alok Mehta answered
The iron complex may be treated as cationic part, and C5H5- is a bidentate ligand therefore name can be assigned as follows “dicyclopentadienyl Iron (II) cation”.

Type of bonding in K4 [Fe(CN)6] is/a
  • a)
    ionic
  • b)
    covalent
  • c)
    metallic
  • d)
    coordinate covalent
Correct answer is option 'A,B,D'. Can you explain this answer?

Shubham Jain answered
The complex K4[Fe(CN)6] whose formula can be written like that of double salt. Fe(CN)2 . 4KCN, dissociates to give K+ and [Fe(CN)6]4- ions in the aqueous solution.

Ferrocyanide ion is a type of​
  • a)
    Square planar complex
  • b)
    Octahedral complex
  • c)
    Tetrahedral complex
  • d)
    Octahedral square planar complex
Correct answer is option 'B'. Can you explain this answer?

Rajeev Saxena answered
Ferricyanide is the anion [Fe(CN)6]3−. It is also called hexacyanoferrate(III) and in rare, but systematic nomenclature, hexacyanidoferrate(III). The most common salt of this anion is potassium ferricyanide, a red crystalline material that is used as an oxidant in organic chemistry.

A magnetic moment of 1.73 BM will be shown by one among the following
  • a)
    [Cu(NH3)4]2+
  • b)
    [Ni(CN)4]2–
  • c)
    TiCl4
  • d)
    [CoCl6]4–
Correct answer is option 'A'. Can you explain this answer?

Ritu Singh answered
The correct answer is Option A.
Electronic configuration of Cu2+  ion in [Cu(NH3)4]2+.
Cu2+ ion =[Ar]3d94s0.
∴Cu2+ ion has one unpaired electron.
Magnetic moment of [Cu(NH3)4]2+ (μ) = BM
where, n = no. of unpaired electrons

Whereas Ni2+ in [Ni(CN)4]2− , Ti4+ in TiCl4 and Co2+ ion [COCl6]4− has 2,0 and 3 unpaired electrons respectively.

The spin only magnetic moment value (in Bohr magneton units) of Cr(CO)6 is
  • a)
    0
  • b)
    2.84
  • c)
    4.90
  • d)
    5.92
Correct answer is option 'A'. Can you explain this answer?

Rahul Bansal answered
The electron configuration is [Ar]3d^5 4s^1.We have to accomodate the 6 Ligands and the fact that CO is a strong ligand.
This results in d^2sp^3 hybridization. Therefore, there are no unpaired electrons in Cr(CO)6. Hence n=0
And the spin only magnetic moment is also 0.

The effective atomic number of Fe in Fe(CO)5 is
  • a)
    36
  • b)
    24
  • c)
    34
  • d)
    26
Correct answer is option 'A'. Can you explain this answer?

Anupama Nair answered
EAN= atomic no of Fe - oxidation state + no of e donated by ligand... Oxidation state of Fe is 0 since CO is neutral ligand... Two donor atoms hence no of e = 2×5=10.... EAN= 26-0+10=36

The number of unpaired electrons in [V(H2O)6]3+ is:
  • a)
    1
  • b)
    4
  • c)
    3
  • d)
    2
Correct answer is 'D'. Can you explain this answer?

Krishna Iyer answered
The metal ion V3+ is in +3 oxidation state, with configuration d2, and the hybridization of metal ion orbitals for ligand bond is d2sp3, where the number of unpaired electrons in [V(H2O)6]3+ is 2.

Tollen’s reagent contains
  • a)
    AgOH
  • b)
    AgNO3
  • c)
    [Ag(NO3)2]+
  • d)
    [Ag(NH3)2]+
Correct answer is option 'B'. Can you explain this answer?

Akash Shah answered
Toilen’s reagent is ammoniacal silver nitrate solution. It is used to distinguish aldehydes and ketones, reducing and non-reducing sugars.

The formula of the complex hexamminecobalt (III) chloride sulphate is
  • a)
    [Co(NH3)6]CISO4
  • b)
    [Co(NH3)6CI]SO4
  • c)
    [Co(NH3)6CISO4]
  • d)
    None of these
Correct answer is 'A'. Can you explain this answer?

Anshika Menon answered
Formula of Complex Hexamminecobalt (III) Chloride Sulphate

The correct answer is 'A' which represents the formula [Co(NH3)6]ClSO4. Let's break down the answer into the following headings:

I. Understanding the Formula
II. Explanation of the Formula
III. Conclusion

I. Understanding the Formula
Before we dive into the formula, let's understand some key terms:
- Complex: A molecule or ion formed by the combination of a metal ion with a ligand (a molecule or ion that can donate a pair of electrons to the metal ion)
- Hexamminecobalt (III) chloride: A complex formed by the combination of cobalt (III) ion with six ammonia molecules and one chloride ion
- Sulphate: A compound containing the sulphate ion (SO4 2-)

II. Explanation of the Formula
The given complex contains cobalt (III) ion, six ammonia molecules (NH3), one chloride ion (Cl-), and one sulphate ion (SO4 2-). The cobalt (III) ion is coordinated by six ammonia molecules forming an octahedral complex. The chloride ion and sulphate ion occupy the remaining two positions of the octahedral complex. Therefore, the formula of the complex is [Co(NH3)6]ClSO4.

III. Conclusion
In conclusion, the formula of the complex hexamminecobalt (III) chloride sulphate is [Co(NH3)6]ClSO4. The complex contains cobalt (III) ion coordinated by six ammonia molecules, one chloride ion, and one sulphate ion.

Which of the following statements is/are correct?
  • a)
    [Co(en)2NO2Cl] Br is cationic complex
  • b)
    [Co(en)3]CI3 produces 3 ions in solution
  • c)
    [Fe(CO)5] is neutral complex
  • d)
    [Cu(NH3)4]SO4 is deep blue colour
Correct answer is option 'A,C,D'. Can you explain this answer?

Nikita Singh answered
[Co(en)3]CI3 produces 4 ions in solution as follows :
[Co(en)3] CI3→ [Co(en)3]3+ + 3CI-
 
  1. is correct as charge on the complex ion will be +1
  2.  is incorrect as the complex will form 4 ions in solution
  3. is correct as there is no charge on the complex
  4. is also correct as cu+2 has blue color in solution
Hence A, C and D are correct.

The complex, [Ni(CN)4]2-, has:
    • a)
      Octahedral structure
    • b)
      Linear structure
    • c)
      Tetrahedral structure
    • d)
      Square planar Structure
    Correct answer is option 'D'. Can you explain this answer?

    Naina Bansal answered
    In case of [Ni(CN)4 ]^2-, oxidation state of Nickel is +2. So, Ni^2+ : 3d^8 4s^0 . Now, cyanide also causes pairing of unpaired electrons, in 3d orbital, all the 8 electrons will get paired, so now, 1 more orbital is left.... and there are 4 ligands to bond with. Hence, the hybridization will be dsp^2 so hence, it is a square planar complex because all dsp^2 complexes are square planar. The singly unpaired electron will pair up only if the ligand field is very strong and that too only in the lower energy orbitals.

    The hybrisation of Co in [Co(H2O)6]3+ is :
    • a)
      d2sp3
    • b)
      dsp2
    • c)
      dsp3
    • d)
      spd3
    Correct answer is option 'A'. Can you explain this answer?

    Rajeev Saxena answered
    In this complex compound the total charge is +3 as H2O is a neutral compound so the oxidation state of cobalt is +3 and the electronic configuration of Co is 3d7 4s2. So, Co(+3)=4d6 and H2O is a weak ligand so there is no pairing of electron. So,4s 4p3 and 4d2 orbital make hybrid orbital to have a hybridization of d2sp3.

    Complex compounds are addition compounds formed by the stoichiometric combination of two or more simple salts but do not decompose into constituent ions completely. The first such complex prepared by Tassaert is hexamine cobalt (III) chloride. Later many such compounds were prepared and their properties were studied. The chloramines complexes of cobalt (III) chromium (III) not only exhibit a spectrum of colours but also differ in the reactivity of their chlorides. Moreover, greater the number of ions produced by a complex in solution, greater is the electrical conductivity. This type of information was obtained for several series of complexes.
    Q. 
    The number of ions per mole of the complex CoCI3 . 5NH3 in aqueous solution will be
    • a)
      3
    • b)
      9
    • c)
      2
    • d)
      4
    Correct answer is option 'A'. Can you explain this answer?

    Suresh Iyer answered
    [Co(NH3)5CI]CI2→[Co(NH3)5CI]2++ 2Cl- 
    Hence, 3 ions are present for one mole of the complex in the solution.

    The complex potassium dicyanodioxalatonickelate (II) in solution produce....... ions.
      Correct answer is '5'. Can you explain this answer?

      Anaya Patel answered
      The structure of potassium dicyanodio xalatonickelate (II) is
      K4[Ni(CN)2(ox)2].
      K4[Ni(CN)2(ox)2] →  4K+ + [Ni(CN)2(ox)2]- 
      This produce 5 ions in solution.

      Number of EDTA molecules required to form an octahedral complex.
        Correct answer is '1'. Can you explain this answer?

        Mira Sharma answered
        One EDTA (ethylenediaminetetraacetic acid) molecule is required to make an octahedral complex with Ca^2+ ion

        In the estimation of hardness of water, the reagent used is
        • a)
          hypo solution
        • b)
          KMnO4
        • c)
          EDTA solution
        • d)
          K2Cr2O7
        Correct answer is option 'C'. Can you explain this answer?

        Preeti Iyer answered
        The EDTA solution can then be used to determine the hardness of an unknown water sample. Since both EDTA and Ca2+ are colorless, it is necessary to use a special indicator to detect the end point of the titration.

         Which of the following statements is not correct as per the nomenclature of coordination compounds is concerned?
        • a)
          The name of neutral ligands is written as such except few like aqua for water.
        • b)
          The oxidation state of a metal in the coordination sphere should be written in roman numerals.
        • c)
          The name of the anionic part should be written first.
        • d)
          The name of the cationic part should be written first.
        Correct answer is 'C'. Can you explain this answer?

        Ashwini Shah answered
        Explanation:

        The correct answer is option C - The name of the anionic part should be written first.

        Explanation:

        The nomenclature of coordination compounds follows certain rules and conventions. Let's discuss each statement and understand why option C is incorrect.

        a) The name of neutral ligands is written as such except a few like aqua for water:

        In coordination compounds, ligands are classified into two categories - neutral ligands and anionic ligands. Neutral ligands are named as they are, without any changes. For example, H2O is named as water, NH3 is named as ammonia, CO is named as carbonyl, etc. However, there are a few exceptions to this rule. For example, H2O is named as aqua when it is a ligand in a coordination compound. So, statement A is correct.

        b) The oxidation state of a metal in the coordination sphere should be written in roman numerals:

        The oxidation state of the metal ion in a coordination compound is indicated by a Roman numeral in parentheses after the name of the metal. This is necessary because the same metal can exhibit different oxidation states in different coordination compounds. For example, Fe(II) represents iron in the +2 oxidation state, while Fe(III) represents iron in the +3 oxidation state. So, statement B is correct.

        c) The name of the anionic part should be written first:

        According to the rules of nomenclature, the name of the cationic part should be written first followed by the name of the anionic part. This is because the cationic part is usually a metal or a positive ion, while the anionic part is usually a ligand or a negative ion. For example, in the coordination compound [Co(NH3)6]Cl3, the cationic part is [Co(NH3)6] (hexaamminecobalt) and the anionic part is Cl3 (trichloride). So, statement C is incorrect.

        d) The name of the cationic part should be written first:

        As mentioned in the explanation for statement C, the name of the cationic part should be written first in the nomenclature of coordination compounds. So, statement D is correct.

        Conclusion:

        Based on the above explanation, the correct answer is option C - The name of the anionic part should be written first.

        When AgNO3 solution is added in excess to 1 M solution of CoCI3 . xNH3, one mole of AgCI is formed. The value of x is
          Correct answer is '4'. Can you explain this answer?

          Nikita Singh answered
          AgNO3 solution is added in excess of 1 M solution of CoCI3 . xNH3.
          CoCl3​.xNH3​+AgNO3​→AgCl (1mole)
          This precipitation of 1 mol of AgCl by this reaction shows that there is only one Cl outside the coordination sphere, which is not as a ligand ( as ligands are not ionisable).
          Hence, the compound must be as follows:(showing the coordination sphere) [Co(NH3​)4​Cl2​]Cl, as this is the octahedral complex, where it is clear that there are only 2 Cl as ligand and other ligands are NH3​. 
          So, 6−2 = 4 NH3​ ligands.

          Only One Option Correct Type
          Direction (Q. Nos. 1-10) This section contains 10 multiple choice questions. Each question has four choices (a), (b), (c) and (d), out of which ONLY ONE is correct.
          Q. 
          Primary and secondary valency of Pt in [Pt(en)2CI2] are
          • a)
            + 4 and - 4
          • b)
            + 4 and 6
          • c)
            + 6 and 4
          • d)
            + 2 and 6
          Correct answer is option 'D'. Can you explain this answer?

          Rahul Bansal answered
          The primary valence is its oxidation number, which is +2 in this case (en is uncharged, and the Cl ligands carry a -1 charge each, so Pt must be +2 to balance).
          Secondary valence is coordination number. The en ligand is bidentate, and Cl is monodentate, so you have 2(2) + 2(1) = 6, so the Pt has a coordination number of 6.

          Which is the diamagnetic?
          • a)
            [CoF6]3-
          • b)
            [Ni(CN)4]2-
          • c)
            [NiCI3]2-
          • d)
            [Fe(CN)6]3-
          Correct answer is option 'B'. Can you explain this answer?

          Niti Mishra answered
          Explanation:

          Diamagnetic substances are those which do not have any unpaired electrons and are not attracted by a magnetic field. On the other hand, paramagnetic substances have unpaired electrons and are attracted by a magnetic field.

          Let's examine the given options to determine which one is diamagnetic.

          [CoF6]3-
          Cobalt has 27 electrons. In this complex, cobalt is in the +3 oxidation state. The six fluoride ions act as ligands and each donate one pair of electrons to the cobalt ion. The complex has a total of 33 electrons, and there are three unpaired electrons in the d-orbitals of the cobalt ion. Therefore, [CoF6]3- is a paramagnetic complex.

          [Ni(CN)4]2-
          Nickel has 28 electrons. In this complex, nickel is in the +2 oxidation state. The four cyanide ions act as ligands and each donate one pair of electrons to the nickel ion. The complex has a total of 34 electrons, and all the electrons are paired. Therefore, [Ni(CN)4]2- is a diamagnetic complex.

          [NiCl4]2-
          Similar to the above complex, nickel has 28 electrons and is in the +2 oxidation state. The four chloride ions act as ligands and each donate one pair of electrons to the nickel ion. The complex has a total of 32 electrons, and all the electrons are paired. Therefore, [NiCl4]2- is a diamagnetic complex.

          [Fe(CN)6]3-
          Iron has 26 electrons. In this complex, iron is in the +3 oxidation state. The six cyanide ions act as ligands and each donate one pair of electrons to the iron ion. The complex has a total of 32 electrons, and there are five unpaired electrons in the d-orbitals of the iron ion. Therefore, [Fe(CN)6]3- is a paramagnetic complex.

          Therefore, the diamagnetic complex among the given options is [Ni(CN)4]2-.

          Can you explain the answer of this question below:

          sp3-hybridisation is found in

          • A:

            [ZnCI4]2-

          • B:

            [Cu(NH3)4]2+

          • C:

            [CuCI4]2-

          • D:

            [Ni(CO)4]

          The answer is A,C,D.

          Dipika Rane answered
          Explanation:

          SP3 hybridization is a type of hybridization where one s orbital and three p orbitals of the same shell of an atom mix to form four sp3 hybrid orbitals. These hybrid orbitals are arranged in a tetrahedral shape around the central atom.

          The given options are:

          a) [ZnCl4]2-
          b) [Cu(NH3)4]2
          c) [CuCl4]2-
          d) [Ni(CO)4]

          a) [ZnCl4]2-: In this complex ion, the central zinc atom is sp3 hybridized. The zinc ion has an electronic configuration of [Ar]3d104s0. The hybridization of the zinc ion takes place by mixing one 4s orbital and three 4p orbitals to form four sp3 hybrid orbitals.

          b) [Cu(NH3)4]2: In this complex ion, the central copper atom is dsp2 hybridized. The copper ion has an electronic configuration of [Ar]3d104s1. The hybridization of the copper ion takes place by mixing one 4s orbital, two 4p orbitals, and one 3d orbital to form five dsp2 hybrid orbitals.

          c) [CuCl4]2-: In this complex ion, the central copper atom is sp3 hybridized. The copper ion has an electronic configuration of [Ar]3d104s1. The hybridization of the copper ion takes place by mixing one 4s orbital and three 4p orbitals to form four sp3 hybrid orbitals.

          d) [Ni(CO)4]: In this complex ion, the central nickel atom is sp3 hybridized. The nickel ion has an electronic configuration of [Ar]3d84s2. The hybridization of the nickel ion takes place by mixing one 4s orbital and three 4p orbitals to form four sp3 hybrid orbitals.

          Conclusion:

          Thus, the correct options are A, C, and D, as all these complex ions have a central atom that is sp3 hybridized. The complex ion in option B has a central copper atom that is dsp2 hybridized.

          Statement Type
          Direction (Q. Nos. 24 and 25) This section is based on Statement I and Statement II. Select the correct answer from the codes given below.
          Q. 
          Statement I : Oxidation state of Fe in Fe(CO)5 is zero.
          Statement II : EAN of Fe in this complex is 36.
          • a)
            Both Statement I and Statement II are correct and Statement II is the correct explanation of Statement I
          • b)
            Both Statement I and Statement II are correct but Statement II is not the correct explanation of Statement I
          • c)
            Statement I is correct but Statement II is incorrect
          • d)
            Statement II is correct but Statement I is incorrect
          Correct answer is option 'B'. Can you explain this answer?

          Shail Chakraborty answered
          Statement I is true because CO is a neutral ligand, Statement II is true because
          EAN of Fe
          = Atomic number of Fe + Electrons gained by coordination
          = 26 + 2 x 5 = 36
          But Statement II is not the correct explanation. Correct explanation is that oxidation state of Fe in Fe(CO)5 is zero because CO is a neutral ligand.

          The volume (in mL) of 0.1 M AgNO3 required for complex precipitation of chloride ions present in 30 mL of 0.01 M solution of [Cr(H2O)5Cl]Cl2, as silver chloride is close to
          • a)
            3
          • b)
            4
          • c)
            5
          • d)
            6
          Correct answer is option 'D'. Can you explain this answer?

          Sanchita Reddy answered
          The chemical reaction between them is...[Cr(H2O)5Cl]Cl2 + {2}AgNO3 ——> {2}AgCl(↓) + [Cr(H2O)5Cl]^2+ + {2}NO3-moles of coordinate compound given = molarity x volume(in litre)mole = 0.01 x (30/1000) = (3/10000)for one mole coordinate compound.. we need 2 mole AgNO3....i.e.,1mole complex ===> 2 mole AgNO3(3/10000) mole ==> (2x3/10000) mole AgNO3molarity = moles/volume (in litre)volume(in litre) = mole / molarityV= (6/10000)/0.1 = (0.6) Litrehence volume required = 0.6litre = 6ml

          For the complex ion dichlorido bis (ethylene diamine) cobalt (III), select the correct statement.
          • a)
            It has three isomers, two of them are optically active and one is optically inactive.
          • b)
            It has three isomers, all of them are optically active.
          • c)
            It has three isomers, all of them are optically inactive.
          • d)
            It has one optically active isomer and two geometrical isomers.
          Correct answer is option 'A'. Can you explain this answer?

          Milan Datta answered
          Explanation:

          The complex ion dichlorido bis(ethylene diamine) cobalt (III) has the formula [Co(en)2Cl2]+. Let's analyze the structure and isomers of this complex ion to determine the correct statement.

          Structure:
          The central cobalt (III) ion is coordinated by two ethylenediamine (en) ligands and two chloride (Cl) ligands. The ethylenediamine ligand is a bidentate ligand, meaning that it can form two coordination bonds with the central metal ion. The chloride ligand is a monodentate ligand, meaning that it can form only one coordination bond with the central metal ion.

          Isomers:
          Isomers are compounds that have the same chemical formula but different structural arrangements. In this case, there are three possible isomers for the complex ion [Co(en)2Cl2]+.

          1. Geometrical isomerism:
          Geometrical isomerism occurs when there is restricted rotation around a bond, resulting in different spatial arrangements. In the case of [Co(en)2Cl2]+, there are two possible geometrical isomers:

          - cis-[Co(en)2Cl2]+: In this isomer, the two ethylenediamine ligands are adjacent to each other, and the two chloride ligands are also adjacent to each other.
          - trans-[Co(en)2Cl2]+: In this isomer, the two ethylenediamine ligands are opposite to each other, and the two chloride ligands are also opposite to each other.

          2. Optical isomerism:
          Optical isomerism occurs when a compound is chiral, meaning it does not possess a plane of symmetry. Chiral compounds exist in two forms known as enantiomers, which are mirror images of each other. In the case of [Co(en)2Cl2]+, there is only one chiral center, which is the cobalt ion.

          - Each geometrical isomer can exist as either an R or S enantiomer, resulting in two optically active isomers.
          - The trans-[Co(en)2Cl2]+ isomer is optically inactive because its mirror image can be superimposed on it.

          Conclusion:
          Based on the analysis, the correct statement is option A. The complex ion dichlorido bis(ethylene diamine) cobalt (III) has three isomers, two of them are optically active (cis-[Co(en)2Cl2]+ R and S enantiomers) and one is optically inactive (trans-[Co(en)2Cl2]+).

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