124 + Interview Questions in Coordination Compounds in Chemistry

101.	What is the correct way of representing nickel in [Ni(CO)4]?(a) Ni(0)(b) Ni(I)(c) Ni(II)(d) Ni(III)The question was asked in semester exam.This interesting question is from Definitions topic in chapter Coordination Compounds of Chemistry – Class 12
Answer» Correct answer is (a) Ni(0) To ELABORATE: The oxidation number of a metal is REPRESENTED as ROMAN numeral in parenthesis PRECEDED by the name of the entity. Since oxidation number of nickel in the GIVEN compound is zero, it is represented as Ni(0).

Discussion

102.	If Pt in PtCl4.2HCl has a secondary valence of 6, how many mols of AgCl will 1 mol of the compound precipitate with excess AgNO3?(a) 0(b) 1(c) 2(d) 4The question was posed to me in an internship interview.Question is from Werner’s Theory of Coordination Compounds topic in chapter Coordination Compounds of Chemistry – Class 12
Answer» Correct answer is (a) 0 For explanation: SINCE the SECONDARY valence is 6, the COMPOUND should have SIX groups linked to Pt ATOM. But it already has six groups linked to it and cannot lose any Cl atoms to form AgCl. Hence, no AgCl will be produced.

Discussion

103.	Coordination number is a characteristic of which of the following?(a) Central atom(b) Ligand(c) Coordination entity(d) Coordination compoundI have been asked this question in an online quiz.Origin of the question is Definitions in division Coordination Compounds of Chemistry – Class 12
Answer» Right answer is (a) Central atom The BEST EXPLANATION: Coordination NUMBER is also known as the secondary valence of a central metal ion in a COMPLEX and is defined as the number of donor ATOMS it is directly bonded to. Hence, coordination number is a quantity associated with the metal ion.

Discussion

104.	Coordination entities with only three ligand groups attached to the metal ion can have d^2sp^3 hybridisation.(a) True(b) FalseI had been asked this question in class test.My question is from Bonding in Coordination Compounds in section Coordination Compounds of Chemistry – Class 12
Answer» The correct CHOICE is (a) True The best EXPLANATION: This happens in the case of didentate ligands which have six pairs of electrons from three molecules. For EXAMPLE, [Co(ox)3]^3- has d^2sp^3 HYBRIDISATION and is DIAMAGNETIC.

Discussion

105.	[Co(en)2(NH3)Cl]^2+ is known to be a diamagnetic complex. What is the type of hybridisation it shows?(a) dsp^2(b) sp^3(c) d^2sp^3(d) sp^3d^2This question was posed to me in examination.My query is from Bonding in Coordination Compounds topic in section Coordination Compounds of Chemistry – Class 12
Answer» Correct OPTION is (c) d^2sp^3 Explanation: Co^3+ has 3d^6 configuration. For a complex to be DIAMAGNETIC, it should have no unpaired electrons. So, the single electrons in the 3d orbital will have to pair up and form 3 pairs leaving two 3d orbitals VACANT. This results in d^2sp^3 HYBRIDISATION.

Discussion

106.	Identify the magnetic nature of the complex from its electronic configuration as shown.(a) Strongly paramagnetic(b) Weakly paramagnetic(c) Diamagnetic(d) FerromagneticThe question was posed to me in a national level competition.The question is from Bonding in Coordination Compounds in section Coordination Compounds of Chemistry – Class 12
Answer» The CORRECT choice is (b) Weakly paramagnetic Best EXPLANATION: There is one unpaired ELECTRON in the 3d orbitals. The presence of unpaired electrons makes a complex paramagnetic. In this CASE, SINCE only 1 unpaired electron is present, it is a weak paramagnet.

Discussion

107.	How many empty orbitals are available in the central metal ion of a complex that has a trigonal bipyramidal geometry?(a) 2(b) 3(c) 4(d) 5I had been asked this question during an online exam.My enquiry is from Bonding in Coordination Compounds topic in portion Coordination Compounds of Chemistry – Class 12
Answer» The correct choice is (d) 5 The explanation: One of the assumptions of VBT is that the number of empty orbitals in the METAL ION for making bonds with the ligands is equal to its CN. A TRIGONAL bipyramidal GEOMETRY has a hybridisation of sp^3d and hence a CN=5.

Discussion

108.	How many types of hybridisation are possible for complexes with a coordination number of 4?(a) 1(b) 2(c) 3(d) 4This question was posed to me at a job interview.I'm obligated to ask this question of Bonding in Coordination Compounds in portion Coordination Compounds of Chemistry – Class 12
Answer» The CORRECT OPTION is (B) 2 Easy EXPLANATION: According to VBT, a complex with CN=4 can have two possible types of hybridisation and hence geometries. The sp^3 hybridisation results in tetrahedral geometry and dsp^2 hybridisation results in square planar geometry.

Discussion

109.	Identify the correct naming for K2[PdCl4].(a) Potassium tetrachlorinepalladium(II)(b) Potassium tetrachlorinepalladate(II)(c) Potassium tetrachloridopalladium(II)(d) Potassium tetrachloridopalladate(II)The question was posed to me in examination.My doubt stems from Nomenclature of Coordination Compounds topic in portion Coordination Compounds of Chemistry – Class 12
Answer» Correct option is (d) POTASSIUM tetrachloridopalladate(II) Easiest EXPLANATION: Since Cl is an anionic ligand, it ends in -o, hence chlorido. Also, the complex ION is anionic, and the metal must end with the suffix -ATE, hence palladate.

Discussion

110.	Which of the following is true regarding a charged coordination entity?(a) The charge is indicated as a subscript outside the square bracket on the right(b) The charge of the complex ion is written in parenthesis while naming the entity(c) The sign of the charge is written after the number(d) The charge on the complex ion is depicted along with the counter ionThe question was posed to me by my college director while I was bunking the class.This key question is from Nomenclature of Coordination Compounds in portion Coordination Compounds of Chemistry – Class 12
Answer» Right option is (C) The sign of the CHARGE is WRITTEN after the NUMBER For explanation: The charge of a coordination entity is written WITHOUT the presence of the counter ion and is indicated outside the square brackets on the right side as a superscript with the number before the sign of charge.

Discussion

111.	Identify the correct naming for K3[Fe(CN)6].(a) Tripotassium hexacyanidoferrate(III)(b) Potassium hexacyanoferrate(III)(c) Tripotassium hexacyanoferrate(III)(d) Potassium hexacyanidoferrate(III)The question was asked in semester exam.The above asked question is from Nomenclature of Coordination Compounds topic in portion Coordination Compounds of Chemistry – Class 12
Answer» CORRECT answer is (d) Potassium hexacyanidoferrate(III) For explanation: The number of CATIONS or anions is not denoted in the name of a coordination compound. In this CASE, the counter ion is named as potassium and not tripotassium. Also, CN is an anionic ligand and should end with -o, with the correct name being cyanido and not CYANO.

Discussion

112.	The coordination number is determined by the number of both, sigma and pi bonds formed by the ligand with the central atom/ion.(a) True(b) FalseI got this question by my college professor while I was bunking the class.I'd like to ask this question from Definitions topic in portion Coordination Compounds of Chemistry – Class 12
Answer» The correct option is (b) False Easy explanation: The CN is FOUND by only considering the NUMBER of SIGMA bonds between the donor atoms and central atom/ion. Pi bonds between ligand and central atom/ion are not counted for this purpose.

Discussion

113.	Identify the coordination sphere in the compound K4[Fe(CN)6].(a) K^+(b) Fe^2+(c) [Fe(CN)6]^4-(d) CN^–I have been asked this question during an interview.Origin of the question is Definitions topic in chapter Coordination Compounds of Chemistry – Class 12
Answer» CORRECT answer is (c) [FE(CN)6]^4- To explain I would say: The coordination sphere refers to the square bracket WITHIN which the central atom/ion and the groups attached to it are enclosed. This is a non-ionisable group as compared to the ENTITY outside the bracket, which is ionisable and is known as the counter ion.

Discussion

114.	In CFT, which of the following ligands will be treated as point dipoles?(a) Cl(b) NO2(c) CN(d) NOI have been asked this question in unit test.My question comes from Bonding in Coordination Compounds in section Coordination Compounds of Chemistry – Class 12
Answer» Correct ANSWER is (d) NO The EXPLANATION: Anionic LIGANDS are treated as POINT charges and neutral ligands are treated as point dipoles in crystal field THEORY.

Discussion

115.	The crystal field theory considers the metal-ligand bond to be a _______ bond.(a) covalent(b) ionic(c) polar(d) hydrogenI have been asked this question in final exam.Asked question is from Bonding in Coordination Compounds in section Coordination Compounds of Chemistry – Class 12
Answer» The CORRECT answer is (b) ionic The explanation: The CFT is an ELECTROSTATIC model which considers the bond between metal ion and the ligand to be ionic arising DUE to the electrostatic INTERACTIONS between them.

Discussion

116.	A coordination complex [MX2L2], has a CN=4 and two unidentate ligands X and L. When the two L ligands are arranged opposite to each other in its geometry, it is called _______ isomer.(a) cis(b) trans(c) fac(d) merThe question was posed to me during an interview.This key question is from Isomerism in Coordination Compounds topic in chapter Coordination Compounds of Chemistry – Class 12
Answer» CORRECT option is (a) cis To explain I would SAY: The shape of the complex will be square planar as the CN is 4 and isomerism cannot be observed in tetrahedral shapes (also CN=4). When a PARTICULAR ligand in this type of complex is arranged opposite to each other, it is a trans isomer, else it is CALLED a cis isomer.

Discussion

117.	The position of ligands in the formula of a mononuclear coordination entity depends on which of the following?(a) The first letter in the name of the ligand(b) Charge on the ligand(c) Atomicity of the ligand(d) Denticity of the ligandI got this question during an interview for a job.This intriguing question comes from Nomenclature of Coordination Compounds in portion Coordination Compounds of Chemistry – Class 12
Answer» The correct OPTION is (a) The first letter in the NAME of the ligand For explanation I WOULD say: The listing of ligands in the formula of mononuclear coordination entities is ACCORDING to ALPHABETICAL order, including abbreviated ligands. It does not depend on the atomicity, denticity or the charge on the ligand.

Discussion

118.	What is the number of unpaired electrons in [Fe(H2O)6]^2+ if it is known to be a high spin complex?(a) 0(b) 2(c) 3(d) 4I got this question during an interview.Origin of the question is Bonding in Coordination Compounds topic in division Coordination Compounds of Chemistry – Class 12
Answer» Correct choice is (d) 4 The EXPLANATION: The configuration of Fe^2+ is 3d^6. The complex has a CN=6 has should have sp^3d^2 hybridisation. This leaves the 3d ORBITALS as it is with 4 UNPAIRED ELECTRONS.

Discussion

119.	Two or more compounds that have the same chemical formula, but different arrangement of atoms are called _______(a) isotopes(b) isotones(c) isomers(d) allotropesThis question was posed to me in an interview for internship.I'm obligated to ask this question of Isomerism in Coordination Compounds in portion Coordination Compounds of Chemistry – Class 12
Answer» The correct answer is (c) isomers For EXPLANATION: Isotopes are forms of one element due to different number of neutrons in each ATOM. Isotones are forms of different elements that have the same number of neutrons and ALLOTROPES are the different PHYSICAL forms in which a given element can EXIST.

Discussion

120.	Hydrate isomerism is a form of ________ isomerism.(a) coordination(b) linkage(c) ionisation(d) solvateI got this question in an interview.Enquiry is from Isomerism in Coordination Compounds topic in section Coordination Compounds of Chemistry – Class 12
Answer» RIGHT CHOICE is (d) SOLVATE Explanation: When the solvate involved in solvate ISOMERISM is water molecules; it is CALLED as hydrate isomerism.

Discussion

121.	Identify the correct formula for hexaaquamanganese(II) ion.(a) [Mn(H2O)6]^2+(b) [Mn(H2O)6]^2-(c) [Mn2(H2O)6]^+(d) [Mn(H2O)6]^+2I got this question by my school principal while I was bunking the class.This is a very interesting question from Nomenclature of Coordination Compounds topic in division Coordination Compounds of Chemistry – Class 12
Answer» The correct answer is (a) [Mn(H2O)6]^2+ To explain I would say: The parenthesis after manganese represents its oxidation state (+2) which is indicated outside the square BRACKET with sign following the number. The H2O MOLECULE is a neutral ligand NAMED as aqua.

Discussion

122.	Which of the following is the central atom/ion in [CoCl(NH3)5]^2+?(a) Co(b) Co^2+(c) Co^3+(d) Cl^–The question was posed to me in an online quiz.Question is taken from Definitions in portion Coordination Compounds of Chemistry – Class 12
Answer» RIGHT choice is (c) Co^3+ To EXPLAIN I would say: The central ion in the given complex ion is cobalt as it accepts electrons to form a bond with CL ATOM and AMMONIA molecules. Since the primary valence of Co in this compound is +3, the ion in Co^3+.

Discussion

123.	What was the term proposed by Werner for the number of groups bound directly to the metal ion in a coordination complex?(a) Primary valence(b) Secondary valence(c) Oxidation number(d) PolyhedraI have been asked this question during an interview.This intriguing question originated from Werner’s Theory of Coordination Compounds topic in section Coordination Compounds of Chemistry – Class 12
Answer» RIGHT choice is (b) Secondary VALENCE Easy explanation: Primary valence of a metal ion is also known as its oxidation number. The secondary valence is equal to coordination number and it is fixed for a metal. Coordination polyhedra is the TERM for the spatial arrangements of the groups/ions around the metal.

Discussion

124.	Which is the counter ion in [Pd(NH3)4]^2+2Cl^–?(a) Pd^2+(b) [Pd(NH3)4]^2+(c) Cl^–(d) It does not have a counter ionI got this question during an internship interview.I would like to ask this question from Werner’s Theory of Coordination Compounds in portion Coordination Compounds of Chemistry – Class 12
Answer» CORRECT option is (c) Cl^– Easy explanation: In coordination compounds, the IONS outside the square BRACKETS are called counter ions, and the SPECIES within the square BRACKET are the coordination entities.

Discussion

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What is the correct way of representing nickel in [Ni(CO)4]?(a) Ni(0)(b) Ni(I)(c) Ni(II)(d) Ni(III)The question was asked in semester exam.This interesting question is from Definitions topic in chapter Coordination Compounds of Chemistry – Class 12

Coordination number is a characteristic of which of the following?(a) Central atom(b) Ligand(c) Coordination entity(d) Coordination compoundI have been asked this question in an online quiz.Origin of the question is Definitions in division Coordination Compounds of Chemistry – Class 12

Coordination entities with only three ligand groups attached to the metal ion can have d^2sp^3 hybridisation.(a) True(b) FalseI had been asked this question in class test.My question is from Bonding in Coordination Compounds in section Coordination Compounds of Chemistry – Class 12

How many types of hybridisation are possible for complexes with a coordination number of 4?(a) 1(b) 2(c) 3(d) 4This question was posed to me at a job interview.I'm obligated to ask this question of Bonding in Coordination Compounds in portion Coordination Compounds of Chemistry – Class 12

Identify the coordination sphere in the compound K4[Fe(CN)6].(a) K^+(b) Fe^2+(c) [Fe(CN)6]^4-(d) CN^–I have been asked this question during an interview.Origin of the question is Definitions topic in chapter Coordination Compounds of Chemistry – Class 12

In CFT, which of the following ligands will be treated as point dipoles?(a) Cl(b) NO2(c) CN(d) NOI have been asked this question in unit test.My question comes from Bonding in Coordination Compounds in section Coordination Compounds of Chemistry – Class 12

The crystal field theory considers the metal-ligand bond to be a _______ bond.(a) covalent(b) ionic(c) polar(d) hydrogenI have been asked this question in final exam.Asked question is from Bonding in Coordination Compounds in section Coordination Compounds of Chemistry – Class 12

What is the number of unpaired electrons in [Fe(H2O)6]^2+ if it is known to be a high spin complex?(a) 0(b) 2(c) 3(d) 4I got this question during an interview.Origin of the question is Bonding in Coordination Compounds topic in division Coordination Compounds of Chemistry – Class 12

Hydrate isomerism is a form of ________ isomerism.(a) coordination(b) linkage(c) ionisation(d) solvateI got this question in an interview.Enquiry is from Isomerism in Coordination Compounds topic in section Coordination Compounds of Chemistry – Class 12

Which of the following is the central atom/ion in [CoCl(NH3)5]^2+?(a) Co(b) Co^2+(c) Co^3+(d) Cl^–The question was posed to me in an online quiz.Question is taken from Definitions in portion Coordination Compounds of Chemistry – Class 12