Basic Terms Questions in English

(C) neutral ligand is a ligand that carries no net electrical charge.
Among the given options:
$1$. Nitrato $(NO_3^-)$ is an anionic ligand with a charge of $-1$.
$2$. Cyano $(CN^-)$ is an anionic ligand with a charge of $-1$.
$3$. Aqua $(H_2O)$ is a neutral ligand with a net charge of $0$.
$4$. Iodo $(I^-)$ is an anionic ligand with a charge of $-1$.
Therefore,the correct option is $C$.

(A) neutral ligand is a ligand that carries no net electrical charge.
$1$. Carbonyl $(CO)$ is a neutral ligand.
$2$. Sulphato $(SO_4^{2-})$ carries a charge of $-2$.
$3$. Oxalato $(C_2O_4^{2-})$ carries a charge of $-2$.
$4$. Bromo $(Br^-)$ carries a charge of $-1$.
Therefore,the correct option is $A$.

(A) Anionic ligands are those that carry a negative charge.
$A$. Isothiocyanato $(NCS^-)$ is an anionic ligand.
$B$. Ammine $(NH_3)$ is a neutral ligand.
$C$. Aqua $(H_2O)$ is a neutral ligand.
$D$. Ethylenediamine $(en)$ is a neutral ligand.
Therefore,the correct option is $A$.

(C) In the coordination complex $K_4[Fe(CN)_6]$,the ligand is the cyanide ion,$CN^-$.
Each $CN^-$ ligand acts as a monodentate ligand,meaning it donates one electron pair through a single donor atom (the carbon atom).
There are $6$ $CN^-$ ligands coordinated to the central metal ion $Fe^{2+}$.
Therefore,in one mole of the complex,there are $6$ moles of $CN^-$ ligands.
Since each $CN^-$ ligand has one donor atom (carbon),the total number of moles of donor atoms is $6 \times 1 = 6$ moles.

(A) To determine which complex contains only neutral ligands,we analyze the ligands in each option:
$A$: $[Co(NH_3)_5(H_2O)]Cl_3$ contains $NH_3$ (neutral) and $H_2O$ (neutral).
$B$: $[Rh(NH_3)_3(SCN)_3]$ contains $NH_3$ (neutral) and $SCN^-$ (anionic).
$C$: $[Pt(en)_2(SCN)_2]Cl_2$ contains $en$ (neutral) and $SCN^-$ (anionic).
$D$: $[Co(NH_3)_3(NO_2)_3]$ contains $NH_3$ (neutral) and $NO_2^-$ (anionic).
Therefore,the complex in option $A$ contains only neutral ligands.

(C) $EDTA^{4-}$ (Ethylenediaminetetraacetate ion) is a hexadentate ligand.
It contains $6$ donor atoms: $2$ nitrogen atoms (from the amine groups) and $4$ oxygen atoms (from the four carboxylate groups).
These $6$ donor atoms simultaneously form coordinate bonds with the central metal atom or ion,making it a hexadentate ligand.
Therefore,the number of donor atoms is $6$.

(A) In $[Co(C_2O_4)_3]^{3-}$,there are three oxalate ligands attached to the central cobalt ion.
Since oxalate $(C_2O_4)^{2-}$ is a bidentate ligand,each oxalate ion provides two donor oxygen atoms.
Therefore,$1 \text{ mole of } (C_2O_4)^{2-} \equiv 2 \text{ moles of donor atoms}$.
Thus,$1 \text{ mole of } [Co(C_2O_4)_3]^{3-} \equiv 3 \times 2 = 6 \text{ moles of donor atoms}$.

(C) The oxalate ligand $(C_2O_4^{2-})$ is a bidentate ligand,meaning it coordinates with the central metal ion through $2$ donor atoms (oxygen atoms) simultaneously.
Since there are $3$ oxalate ligands attached to the central $Fe^{3+}$ ion,the total coordination number is calculated as:
$\text{Coordination Number} = (\text{Number of ligands}) \times (\text{Denticity of ligand})$
$\text{Coordination Number} = 3 \times 2 = 6$.

(D) $NO_2^{-}$ (nitrite) is an ambidentate ligand which has two donor atoms,$N$ and $O$,but uses only one of them at a time to form a coordinate bond.
It is termed as 'nitro' (for $N$-bonded ligand) and 'nitrito' (for $O$-bonded ligand).

(C) neutral coordination complex is one where the coordination sphere carries no net charge.
$1$. Pentaamminecobalt$(III)$ sulphate: $[Co(NH_3)_5(SO_4)]Cl$ or similar ionic forms are cationic complexes.
$2$. Potassium trioxalatoaluminate$(III)$: $K_3[Al(C_2O_4)_3]$ is an anionic complex.
$3$. Diamminedichloroplatinum$(II)$: $[Pt(NH_3)_2Cl_2]$ has a net charge of $0$ $(+2 + 2(0) + 2(-1) = 0)$,making it a neutral complex.
$4$. Potassium hexacyanoferrate$(III)$: $K_3[Fe(CN)_6]$ is an anionic complex.

(B) heteroleptic complex is a coordination compound in which the central metal ion is bonded to more than one type of donor group (ligand).
In the complex $[Fe(H_2O)_5(NCS)]^{2+}$,the central metal ion $Fe^{2+}$ is bonded to two different types of ligands: $H_2O$ and $NCS^-$.
Therefore,it is a heteroleptic complex.
In contrast,the other complexes $[Co(NO_2)_6]^{3-}$,$[Cu(NH_3)_4]^{2+}$,and $[Co(C_2O_4)_3]^{3-}$ are homoleptic complexes because they contain only one type of ligand.

(A) monodentate ligand is a ligand that binds to the central metal atom through only one donor atom.
$CN^{-}$ (cyanide) is a monodentate ligand.
$C_2O_4^{2-}$ (oxalate) is a bidentate ligand.
$en$ (ethylenediamine) is a bidentate ligand.
$SCN^{-}$ (thiocyanato) is an ambidentate ligand,which acts as a monodentate ligand.
In the given options,Tetracyanonickelate$(II)$ ion,$[Ni(CN)_4]^{2-}$,contains the monodentate ligand $CN^{-}$. Therefore,option $A$ is correct.

(B) The reaction of a coordination complex with excess silver nitrate $(AgNO_3)$ precipitates the ionisable chloride ions as silver chloride $(AgCl)$.
According to the stoichiometry of the reaction:
$[M(X)_n]Cl_2 + 2AgNO_3 \rightarrow [M(X)_n](NO_3)_2 + 2AgCl$
Since $1 \ mole$ of the complex reacts to form $2 \ moles$ of $AgCl$,it indicates that there are $2 \ moles$ of ionisable $Cl^{-}$ ions present outside the coordination sphere.

(B) complex is cationic if the coordination sphere carries a positive charge.
$Na_4[Fe(CN)_6]$ dissociates into $4Na^+$ and $[Fe(CN)_6]^{4-}$,which is an anionic complex.
$[Co(NH_3)_5Cl]SO_4$ dissociates into $[Co(NH_3)_5Cl]^{2+}$ and $SO_4^{2-}$,which is a cationic complex.
$[Ni(CO)_4]$ is a neutral complex as it has no charge.
$K_3[Fe(CN)_6]$ dissociates into $3K^+$ and $[Fe(CN)_6]^{3-}$,which is an anionic complex.
Therefore,the correct option is $B$.

(A) An ambidentate ligand is a ligand that can coordinate to a central metal atom through two different donor atoms.
In the complex Triamminetrinitrocobalt $(III)$,the nitro group $(-NO_2)$ is an ambidentate ligand because it can coordinate through either the nitrogen atom (nitro) or the oxygen atom (nitrito).

(A) $NH_3$ is a neutral ligand.
All other options ($Chloro$,$Sulphato$,$Nitrito$) are anionic ligands.
Anionic ligands typically end with the suffix '$o$'.

(B) The oxalate ion is represented by the formula $C_2O_4^{2-}$.
In the structure of the oxalate ion,there are two oxygen atoms that carry a negative charge and possess lone pairs of electrons,which act as donor atoms for coordination with a central metal ion.
Therefore,each oxalate ion has $2$ donor atoms.
Consequently,in $1 \text{ mole}$ of oxalate ion,there are $2 \text{ moles}$ of donor atoms.

(A) neutral ligand is a ligand that carries no net electrical charge.
Among the given options:
$A$. Ammine $(NH_3)$ is a neutral molecule.
$B$. Nitrato $(NO_3^-)$ carries a $-1$ charge.
$C$. Cyano $(CN^-)$ carries a $-1$ charge.
$D$. Chloro $(Cl^-)$ carries a $-1$ charge.
Therefore,the correct answer is Ammine.

(C) The complex is Pentaamminecarbonatocobalt$(III)$ chloride: $[Co(NH_3)_5(CO_3)]Cl$.
In this complex,$NH_3$ is a neutral ligand and $CO_3^{2-}$ is an anionic ligand.

(A) $\text{Cyanide ion}$ $(CN^{-})$ is a monodentate ligand because it coordinates to the central metal atom through only one donor atom.
$\text{Ethylenediamine}$ and $\text{Oxalate ion}$ are bidentate ligands.
$\text{Ethylenediaminetetraacetate}$ $(EDTA^{4-})$ is a hexadentate ligand.

(A) heteroleptic complex is a coordination compound in which the central metal atom or ion is bonded to more than one type of donor group (ligand).
Let us analyze the given complexes:
$A$. $[Co(NH_3)_4(H_2O)_2]Cl_3$: Here,the central metal $Co$ is bonded to two different types of ligands,$NH_3$ and $H_2O$. Thus,it is a heteroleptic complex.
$B$. $[Co(NH_3)_6]Br_3$: Here,the central metal $Co$ is bonded to only one type of ligand,$NH_3$. Thus,it is a homoleptic complex.
$C$. $K_2[Zn(OH)_4]$: Here,the central metal $Zn$ is bonded to only one type of ligand,$OH^-$. Thus,it is a homoleptic complex.
$D$. $[Ni(CO)_4]$: Here,the central metal $Ni$ is bonded to only one type of ligand,$CO$. Thus,it is a homoleptic complex.
Therefore,the correct option is $A$.

(D) Complexes in which the central metal ion is coordinated by more than one type of donor groups (ligands) are known as heteroleptic complexes.
In option $(A)$,$(B)$,and $(C)$,the metal ion is surrounded by only one type of ligand.
In option $(D)$,the central metal ion $Co^{3+}$ is coordinated by two different types of ligands: $H_2O$ and $NH_3$.
Therefore,$[Co(H_2O)(NH_3)_5]I_3$ is a heteroleptic complex.

(B) Ethylenediamine $(en)$ is $NH_2CH_2CH_2NH_2$.
It has two donor nitrogen atoms,each with a lone pair of electrons,which can coordinate to the central metal ion simultaneously.
Therefore,it is a bidentate ligand.

(B) neutral complex is one where the coordination sphere carries no net charge.
In $\left[Co(NO_2)_3(NH_3)_3\right]$,the oxidation state of $Co$ is $+3$,and the ligands are $3 \times NO_2^-$ $(-3)$ and $3 \times NH_3$ $(0)$. The total charge is $(+3) + (-3) + (0) = 0$.
Therefore,$\left[Co(NO_2)_3(NH_3)_3\right]$ is a neutral complex.
$\left[Co(H_2O)(NH_3)_5\right]I_3$ and $\left[Fe(H_2O)_3(NCS)\right]Cl_2$ are cationic complexes,while $Na\left[Co(NO_2)_6\right]$ is an anionic complex.

(C) In the complex $[Co(H_2O)(NH_3)_5]I_3$,the central metal ion is $Co^{3+}$.
There are $5$ $NH_3$ ligands and $1$ $H_2O$ ligand attached to the central metal ion.
All these ligands ($NH_3$ and $H_2O$) are monodentate,meaning each ligand provides only $1$ donor atom.
Therefore,the total number of donor atoms is $5 \times 1 + 1 \times 1 = 6$.

(C) An anionic complex is a coordination entity that carries a net negative charge.
In the given options,$[Ni(CN)_4]^{2-}$ is a complex ion with a charge of $-2$,making it an anionic complex.
Therefore,the correct option is $C$.

(B) The complex $K_3[Al(C_2O_4)_3]$ is Potassium trioxalatoaluminate$(III)$.
In this complex,the ligand is the oxalate ion,$C_2O_4^{2-}$,which is an anionic ligand.
Other options contain neutral ligands like $NH_3$ (ammine) or $H_2O$ (aqua).

(A) $Aqua$ $(H_2O)$ is a neutral ligand because it does not carry any electrical charge.
On the other hand,$Sulphato$ $(SO_4^{2-})$,$Carbonato$ $(CO_3^{2-})$,and $Bromo$ $(Br^-)$ are anionic ligands.

(D) $EDTA$ stands for Ethylenediaminetetraacetate ion.
It contains two nitrogen atoms and four oxygen atoms as donor sites.
Since it can bind to the central metal atom through six donor atoms simultaneously,it is classified as a hexadentate ligand.

(A) cationic sphere complex is one where the coordination entity carries a positive charge.
$1$. Tetraamminecopper$(II)$ ion: $[Cu(NH_3)_4]^{2+}$ (Cationic)
$2$. Tetracyanonickelate$(II)$ ion: $[Ni(CN)_4]^{2-}$ (Anionic)
$3$. Trioxalatocobaltate$(III)$ ion: $[Co(C_2O_4)_3]^{3-}$ (Anionic)
$4$. Triamminetrinitrocobalt$(III)$: $[Co(NH_3)_3(NO_2)_3]$ (Neutral)
Therefore,the tetraamminecopper$(II)$ ion is a cationic sphere complex.

(B) monodentate ligand is a ligand that binds to the central metal atom through only one donor atom.
$CN^{-}$,$OH^{-}$,and $Cl^{-}$ are all monodentate ligands as they have only one donor site.
$H_2N(CH_2)_2NH_2$ (ethylenediamine) is a bidentate ligand because it has two nitrogen donor atoms that can bind to the central metal atom simultaneously.
Therefore,$H_2N(CH_2)_2NH_2$ is not a monodentate ligand.

(A) Complexes in which the metal ion is bound to only one type of donor atom or ligand are called homoleptic complexes.
In $\left[Co(NH_3)_6\right]^{3+}$,the central metal ion $Co^{3+}$ is bonded only to $NH_3$ ligands.
Therefore,$\left[Co(NH_3)_6\right]^{3+}$ is a homoleptic complex.
In other options,the metal ion is bonded to more than one type of ligand (e.g.,$NH_3$ and $Cl^-$),making them heteroleptic complexes.

(D) In $[Fe(C_2O_4)_3]^{3-}$,the ligand is oxalate ion $(C_2O_4^{2-})$,which is a bidentate ligand.
Each bidentate ligand donates two donor atoms to the central metal ion.
Since there are $3$ oxalate ligands,the total number of donor atoms attached to the central $Fe^{3+}$ ion is $3 \times 2 = 6$.
Therefore,the coordination number of the central metal ion is $6$.

(A) In the complex 'Pentacarbonyl iron$(0)$',the formula is $[Fe(CO)_5]$.
The ligand present is carbonyl $(CO)$,which is a neutral ligand.
In contrast,the other options contain anionic ligands: oxalate $(C_2O_4^{2-})$,nitro $(NO_2^-)$,and cyano $(CN^-)$.

(B) . $[Co(NH_3)_6]Cl_3 \rightarrow$ Cationic sphere complex
$B$. $K_4[Fe(CN)_6] \rightarrow$ Anionic sphere complex (The coordination entity $[Fe(CN)_6]^{4-}$ carries a negative charge)
$C$. $[Co(NH_3)_4Cl_2]^+ \rightarrow$ Cationic sphere complex
$D$. $[Co(NH_3)_5Cl]SO_4 \rightarrow$ Cationic sphere complex

(D) To identify an anionic complex,we look for a complex ion that carries a negative charge.
$A$: $\left[Pt(en)_2(SCN)_2\right]^{2+}$ is a cationic complex.
$B$: $\left[Co(NH_3)_5(CO_3)\right]Cl$ dissociates into $\left[Co(NH_3)_5(CO_3)\right]^{+}$ and $Cl^-$,making it a cationic complex.
$C$: $\left[Fe(CO)_5\right]$ is a neutral complex.
$D$: $Na_3\left[Co(NO_2)_6\right]$ dissociates into $3Na^+$ and $\left[Co(NO_2)_6\right]^{3-}$. Since the complex ion $\left[Co(NO_2)_6\right]^{3-}$ carries a negative charge,it is an anionic complex.

(A) ligand with a single donor atom is called a monodentate ligand.
In $OH^{-}$,only the oxygen atom acts as a donor atom.
$NO_2^{-}$ is an ambidentate ligand (can donate through $N$ or $O$).
$SCN^{-}$ is an ambidentate ligand (can donate through $S$ or $N$).
$(C_2O_4)^{2-}$ is a bidentate ligand (donates through two oxygen atoms).

(C) cationic complex is one where the coordination sphere carries a positive charge.
$A$. Trioxalatocobaltate $(III)$ ion: $\left[Co(C_2O_4)_3\right]^{3-}$ (Anionic complex)
$B$. Triamminetrinitrocobalt $(III)$: $\left[Co(NH_3)_3(NO_2)_3\right]$ (Neutral complex)
$C$. Pentaamminechlorocobalt $(III)$ chloride: $\left[Co(NH_3)_5Cl\right]Cl_2$. Upon dissociation,it gives $\left[Co(NH_3)_5Cl\right]^{2+} + 2Cl^-$. This is a cationic complex.
$D$. Potassium tetracyanonickelate $(II)$: $K_2\left[Ni(CN)_4\right]$. Upon dissociation,it gives $2K^+ + \left[Ni(CN)_4\right]^{2-}$. This is an anionic complex.

(B) neutral complex is a coordination compound that carries no net charge on the coordination sphere.
In the complex $[Co(NO_2)_3(NH_3)_3]$,the oxidation state of $Co$ is $+3$,the charge of three $NO_2^-$ ligands is $-3$,and $NH_3$ is a neutral ligand.
Therefore,the net charge is $(+3) + (-3) + 0 = 0$.
Thus,$[Co(NO_2)_3(NH_3)_3]$ is a neutral complex.

(A) The complex $[Pt(NH_3)_2 Cl_2]$ is a neutral coordination compound because it carries no net charge.
In this complex,both $NH_3$ and $Cl^-$ ligands are directly bonded to the central metal atom $Pt$ within the coordination sphere.
The coordination number of $Pt$ is determined by the number of donor atoms attached to it,which is $2 (NH_3) + 2 (Cl) = 4$.
The oxidation state of $Pt$ is calculated as: $x + 2(0) + 2(-1) = 0$,which gives $x = +2$.

(A) neutral ligand is a ligand that carries no net electrical charge.
$1$. Thiocyanate $[SCN]^-$ is an anionic ligand with a charge of $-1$.
$2$. Ammine $[NH_3]$ is a neutral ligand.
$3$. Aqua $[H_2O]$ is a neutral ligand.
$4$. Carbon monoxide $[CO]$ is a neutral ligand.
Therefore,Thiocyanate is not a neutral ligand.

(A) Complex compounds in which all the ligands bound to the metal center are identical are known as homoleptic complexes.
Complexes in which the metal atom or ion is linked with more than one kind of ligand are known as heteroleptic complexes.
$1. \left[Co(NH_3)_6\right] Cl_3$: All ligands are $NH_3$ (identical),so it is a homoleptic complex.
$2. \left[Co(NH_3)_4 Cl_2\right]$: Ligands are $NH_3$ and $Cl^-$ (different),so it is a heteroleptic complex.
$3. \left[Co(NH_3)_5 Cl\right] SO_4$: Ligands are $NH_3$ and $Cl^-$ (different),so it is a heteroleptic complex.
$4. \left[Co(ONO)(NH_3)_5\right] Cl_2$: Ligands are $ONO^-$ and $NH_3$ (different),so it is a heteroleptic complex.

(D) cationic complex is a coordination compound in which the complex ion carries a net positive charge.
In the option $D$,the complex $[PtBr_2(NH_3)_4] Br_2$ dissociates as:
$[PtBr_2(NH_3)_4] Br_2 \rightarrow [PtBr_2(NH_3)_4]^{2+} + 2Br^{-}$
Here,the complex ion $[PtBr_2(NH_3)_4]^{2+}$ has a positive charge,making it a cationic complex.
Options $A$ and $C$ are anionic complexes,and option $B$ is a neutral complex.

(A) Ethylene diaminetetraacetic acid $(EDTA)$ is an amino polycarboxylic acid with the formula $(HO_2CCH_2)_2NCH_2CH_2N(CH_2CO_2H)_2$.
In this structure,there are two nitrogen atoms present in the ethylene diamine backbone.
Therefore,the number of $N$ atoms in $EDTA$ is $2$.

(A) Complex compounds in which all the ligands bound to the metal center are identical are known as homoleptic complexes.
Complexes in which the metal atom or ion is linked with more than one kind of ligand are known as heteroleptic complexes.
In $[Co(NH_3)_6]^{3+}$,all six ligands are $NH_3$ molecules,which are identical. Therefore,it is a homoleptic complex.
In the other options,there are different types of ligands (e.g.,$NH_3$ and $Cl^-$,or $NH_3$ and $H_2O$),making them heteroleptic complexes.

(A) The complex is $Na_4[Fe(CN)_6]$.
$1$. The complex ion is $[Fe(CN)_6]^{4-}$,which carries a $-4$ charge.
$2$. To find the oxidation state of $Fe$ $(x)$:
$x + 6(-1) = -4$
$x - 6 = -4$
$x = +2$
$3$. The coordination number $(C.N.)$ of $Fe$ is determined by the number of ligands attached,which is $6$ ($CN^-$ is a monodentate ligand).
Therefore,the statement that the complex ion carries a $-4$ charge is true.

(B) The coordination number is defined as the total number of sigma bonds formed by the central metal atom with the ligands.
For monodentate ligands,the coordination number equals the number of ligands.
For polydentate ligands,the coordination number is the number of ligands multiplied by their denticity.
In $[Co(en)_3]^{3+}$,the ligand $en$ (ethylenediamine) is a bidentate ligand.
Therefore,the number of ligands is $3$,but the coordination number is $3 \times 2 = 6$.
Thus,the coordination number is not equal to the number of ligands.

(B) complex is homoleptic if the metal atom is bonded to only one type of donor atom/ligand. $A$ complex is cationic if the coordination sphere carries a positive charge.
$1$. $\left[CoCl_{2}(en)_{2}\right] Cl$: Heteroleptic (contains $Cl^-$ and $en$) and cationic.
$2$. $\left[Fe(H_{2}O)_{6}\right] Cl_{3}$: Homoleptic (only $H_{2}O$ ligands) and cationic $(\left[Fe(H_{2}O)_{6}\right]^{3+})$.
$3$. $K\left[Ag(CN)_{2}\right]$: Homoleptic but anionic $(\left[Ag(CN)_{2}\right]^{-})$.
$4$. $\left[Fe(CO)_{5}\right]$: Homoleptic but neutral.
Therefore,the correct option is $\left[Fe(H_{2}O)_{6}\right] Cl_{3}$.

(B) The chemical formula for hexamminecobalt$(III)$ chloride is $[Co(NH_3)_6]Cl_3$.
In this complex,the central metal ion is $Co^{3+}$.
The coordination number of $Co$ is $6$ (since there are $6$ $NH_3$ ligands).
The oxidation state of $Co$ is $+3$.
Since all ligands are the same $(NH_3)$,it is a homoleptic complex.
It is a cationic complex because the complex ion is $[Co(NH_3)_6]^{3+}$.
Therefore,the statement that the oxidation state of cobalt is $+3$ is true.

(B) complex is heteroleptic if it contains more than one type of ligand attached to the central metal atom.
It is cationic if the complex ion carries a positive charge.
In $[Co(NH_{3})_{4}Cl_{2}]Cl$,the coordination sphere is $[Co(NH_{3})_{4}Cl_{2}]^{+}$,which contains two different ligands ($NH_{3}$ and $Cl^{-}$) and carries a positive charge.
Thus,it is both heteroleptic and cationic.