Question
Explain with two examples each of the following: Coordination entity, ligand coordination number, coordination polyhedron, homoleptic and heteroleptic.
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Answer
Coordination entity: This entity usually constitutes a central metal atom or ion, to which are attached a fixed number of other atoms or ions or groups by coordinate bonds. Examples are $[Ni(CO)_4], [COC]_3(NH_3)_3],$ etc.
Ligands: It is an ion having at least one lone pair of electrons and capable of forming a coordinate bond with central atom/ion in the coordination entity.
Examples are: $Cl^-, (OH)^-, (CN)^-$ etc.
Coordinate number: The total number of coordinate bonds with which central atom/ion is linked to ligands in the coordination entity is called coordination number of central atom / ion.
Coordination polyhedron: The spatial arrangement of the ligands which are directly attached to the central atom / ion defines a coordination polyhedron about the central atom.
Examples are: $[Co(NHM_3)_6]^{3+}$ is octahedral, $[Ni(CO)_4]$ is tetrahedral.
Homoleptic and hedroleptic: Complexes in which a metal is bound to only one kind of donor groups are known as homoleptic.
Example $[CO(NH_3)_6]^{3+}$
Complex in which a metal is bound to more than one kind of donor groups are called hetroleptic. Example: $ [Co(NH_3)_4Cl_2]^+$
Ligands: It is an ion having at least one lone pair of electrons and capable of forming a coordinate bond with central atom/ion in the coordination entity.
Examples are: $Cl^-, (OH)^-, (CN)^-$ etc.
Coordinate number: The total number of coordinate bonds with which central atom/ion is linked to ligands in the coordination entity is called coordination number of central atom / ion.
Coordination polyhedron: The spatial arrangement of the ligands which are directly attached to the central atom / ion defines a coordination polyhedron about the central atom.
Examples are: $[Co(NHM_3)_6]^{3+}$ is octahedral, $[Ni(CO)_4]$ is tetrahedral.
Homoleptic and hedroleptic: Complexes in which a metal is bound to only one kind of donor groups are known as homoleptic.
Example $[CO(NH_3)_6]^{3+}$
Complex in which a metal is bound to more than one kind of donor groups are called hetroleptic. Example: $ [Co(NH_3)_4Cl_2]^+$
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Match the items of Column I with items of Column II and assign the correct code:
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Column I
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Column II
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$(A)$
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Pendulum
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$(1)$
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Chrome steel
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$(B)$
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Malachite
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$(2)$
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Nickel steel
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$(C)$
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Calamine
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$(3)$
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$Na_3AlF_6$
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$(D)$
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Cryolite
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$(4)$
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$CuCO_3.Cu (OH)_2$
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$(5)$
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$ZnCO_3$
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-
$A (1) B (2) C (3) D (4)$
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$A (2) B (4) C (5) D (3)$
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$A (2) B (3) C (4) D (5)$
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$A (4) B (5) C (3) D (2)$
$i.$ Give reasons$:$
$a.$ Although $- NH _2$ group is o$/$p directing in electrophilic substitution reactions, yet aniline, on nitration gives good yield of m$-$nitroaniline.
$b. \left( CH _3\right)_2 NH$ is more basic than $\left( CH _3\right)_3 N$ in an aqueous solution.
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$a. CH _3 CH _2 NH _2$ and $\left( CH _3 CH _2\right)_2 NH$
$b.$ Aniline and $CH _3 NH _2$
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$b. \left( CH _3\right)_2 NH$ is more basic than $\left( CH _3\right)_3 N$ in an aqueous solution.
$c.$ Ammonolysis of alkyl halides is not a good method to prepare pure primary amines.
$ii.$ Distinguish between the following$:$
$a. CH _3 CH _2 NH _2$ and $\left( CH _3 CH _2\right)_2 NH$
$b.$ Aniline and $CH _3 NH _2$
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Column I
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Column II
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i.
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Soda water
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a.
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A solution of gas in solid.
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ii.
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Sugar solution
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b.
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A solution of gas in gas.
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iii.
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German silver
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c.
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A solution of solid in liquid.
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iv.
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Air
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d.
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A solution of solid in solid.
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v.
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Hydrogen gas in palladium
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e.
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A solution of gas in liquid.
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f.
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A solution of liquid in solid.
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