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The correct OPTION is (d) It can DISTINGUISH between strong and WEAK LIGANDS

Best explanation: One of the limitations of VBT is that it cannot differentiate between weak and strong ligands. The other OPTIONS are also its limitations.

The correct answer is (a) Linear

The explanation is: The hybridisation TYPE is sp which involves only TWO orbitals, so the GEOMETRY has to be linear and the coordination number is 2.

Correct ANSWER is (d) octahedral

The best explanation: Complexes having octahedral GEOMETRY can have either sp^3d^2 or d^2sp^3 HYBRIDISATION depending on WHETHER the outer or inner d orbitals are involved in hybridisation RESPECTIVELY.

The CORRECT option is (a) 0

Easiest explanation: The entity shown has a CN=6 as oxalate is a bidentate ligand. The structure of the entity will be same no MATTER which POSITIONS in the geometry each of the oxalate ligands occupy because their RELATIVE positions will REMAIN the same in each case.

The correct OPTION is (C) [CoCl2(en)2]Cl

The explanation: The COMPOUNDS Hg[Co(SCN)4], [Cr(H2O)5(NO2)]Cl2 and K[Cr(NH3)2(ONO)4] have ambidentate ligands thiocyanate or nitrate in them and these ligands can bind through DIFFERENT donor atoms to produce different structures or isomers.

Correct answer is (d) The coordination entity in the formula of coordination compounds

Best explanation: The coordination entity consisting of the metal atom/ion followed by LIGANDS is enclosed WITHIN square BRACKETS and not in parenthesis.

Right option is (d) Potassium ferrocyanide

Easiest explanation: Potassium ferrocyanide, K4[FE(CN6)], is a complex salt that does not dissociate into Fe^2+ and CN^– ions when DISSOLVED in WATER. The other THREE, i.e., potash alum, carnallite and MOHR’s salt are double salt that dissociate into simple ions completely when dissolved in water.

The correct CHOICE is (b) COMPLEX ion

Best explanation: [Fe(CN)6]^4- is the COORDINATION complex ion of the coordination compound K4[Fe(CN6)], or potassium ferrocyanide, which is ALSO a complex SALT. Coordination complexes are also known as coordination entities.

The CORRECT choice is (a) tetra

The explanation: The terms bis, TRIS, TETRAKIS are used when the NAMES of the LIGAND include a numerical prefix. Else, the prefixes used are mono, di, tri, tetra, etc.

Correct choice is (C) ionisation

Easiest explanation: The SULPHATE counter ion is a potential LIGAND and can displace the Cl atom to MAKE the latter the counter ion.

Right answer is (a) [Co(NH3)6]Cl3

For explanation I would SAY: [Co(NH3)6]Cl3 consists of only AMMONIA ligands in the complex and is hence homoleptic. The rest of the compounds consists of two kinds of ligates, either NH3 and Cl or NH3 and CO3, and hence they are HETEROLEPTIC.

The correct answer is (a) LEWIS acid

Easy explanation: A Lewis acid is a species that can accept an electron pair. All CATIONS are Lewis acids. Since the central atom of a COORDINATION complex is METAL and always accept ELECTRONS, it is a Lewis acid.

Correct choice is (b) Purple

To EXPLAIN I would say: The different compounds of COBALT(III) chloride with ammonia show distinct properties, most NOTABLY with respect to colour and conductivity measurements in solution.

Correct answer is (d) VSEPR THEORY

For explanation I would SAY: The VSEPR Theory explains the structure of individual molecules BASED on the electron PAIRS in their atoms. VBT, CFT, LFT and MOT are theories that explain the nature of bonding in coordination compounds.

Right choice is (b) False

The best EXPLANATION: GEOMETRICAL isomerism takes place only in heteroleptic ligands as there is more than one TYPE of bonding group that can be arranged in different possible MANNERS to GIVE rise to isomers.

Correct option is (a) True

The explanation is: A protein is a macromolecule that consists of atoms that may DONATE ELECTRONS to a metal ion to FORM a COORDINATE bond, and hence ACT as a ligand.

Right choice is (a) True

For explanation I would say: Mono, DI, TRI, etc. are used when NAME of ligands don’t have a numerical PREFIX. If not, then bis, tris and tetrakis are used as prefixes.

Correct choice is (a) cobalt(III)

Explanation: The complex ion given is cationic and hence the metal is named same as the element. Also, the oxidation NUMBER of cobalt is +3 as (en) is a neutral LIGAND and Cl has -1 charge. THUS, the correct naming for CO is cobalt(III).

Correct answer is (b) +2

For EXPLANATION: This COMPOUND, also known as PRUSSIAN blue, dissociates into 4 Fe^3+ and 3[Fe(CN)6]^4- ions, of which the latter is the coordination entity having a CHARGE of -4. The Fe atom in question is the one inside the bracket. Since CN has a charge of -1 and there are 6 of them, the primary valence of Fe will be 6 – 4 = +2.

The correct option is (b) False

Best EXPLANATION: According to Werner’s POSTULATES, primary valences are ionizable and are satisfied by NEGATIVE ions. Whereas, secondary valences are non-ionizable, and these are satisfied by NEUTRAL MOLECULES or negative ions.

The correct answer is (b) False

To explain: The atomic number of Mn is 25 and the outer SHELL configuration of Mn^2+ is 3D^5. Four out of these five electrons pair up leaving 1 unpaired electron in 3d orbital and forming d^2sp^3 hybridisation. THUS, it is paramagnetic.

The correct answer is (d) 6

The explanation: There are three oxalate groups attached to the central ION in the GIVEN compound, but SINCE oxalate is a didentate ligand, there are a total of 6 donor atoms to which the metal is directly bonded. THUS, the CN of Cr in K3[Cr(C2O4)3] is 6.

Correct option is (b) dextro

Explanation: The optical isomers are of two TYPES BASED on the direction they rotate the plane of polarised light in a polarimeter. If it rotates it to the RIGHT, it is called dextro and if it rotates it to the left, it is called LAEVO.

Correct answer is (c) Linkage isomerism

The explanation: GEOMETRIC and optical isomerism are types of STEREOISOMERISM in which the chemical bonds remain same. The two structures shown have different chemical bonds between the central atom (Co) and the ligand GROUP (NO2). Nitrate is an AMBIDENTATE ligand which can result in two forms in the entities it is present in. If it links through N atom, it forms nitrito-N form (NO2) as in FIGURE i), and if it binds through O atom, it forms nitrito-O form (ONO) as in figure ii). This type of isomerism is called linkage isomerism.

The CORRECT CHOICE is (d) ambidentate

The best EXPLANATION: Ambidentate ligands can bind through either one of their TWO DONOR atoms and can result in different forms. These forms are called linkage isomers.

The correct answer is (b) False

The best I can explain: The prefix DI is used only once for chlorido. For the PPh3 LIGAND, the prefix bis is used instead, as PPh3 (triphenylphosphine) already includes a NUMERICAL prefix in its NAME.

The correct ANSWER is (c) Homoleptic

To elaborate: UNIDENTATE and chelate are words associated with ligands, whereas coordination COMPLEXES can be either homoleptic or heteroleptic depending upon WHETHER only one KIND or different kinds of ligands linked to the metal atom/ion respectively.

Correct choice is (a) Square planar [MXL3]

For explanation: In square planar complexes, the type [MXL3] does not have any isomers as there is no pair of LIGANDS that can be arranged adjacent to or opposite each other to FORM cis or TRANS forms respectively. All possible COMBINATIONS result in the same spatial arrangement.

Correct choice is (c) 3

For EXPLANATION: Firstly, the COMPOUND can have 2 geometric ISOMERS, cis and TRANS, depending on whether similar ligands are placed adjacent to or opposite each other. Furthermore, one of them, i.e. the cis form is optically active and has two non-superimposable forms. This means that the cis form is both a geometric isomers as well as an optical isomer. Hence, there are 3 stereoisomers (1 geometric, 1 optical, 1 both geometric and optical).

The correct choice is (C) fac

Explanation: Octahedral ENTITIES of the type [MA3B3] form two types of ISOMERS based on WHETHER the same ligand groups occupy adjacent positions on the octahedral face (fac) or positions around the meridian of the OCTAHEDRON (mer).

The correct answer is (b) 2

For explanation I would say: In a complex of such TYPE, the two A ligands can be ARRANGED EITHER adjacent to or opposite each other to form cis and trans ISOMERS RESPECTIVELY, making it a total of two possible isomers.

The correct CHOICE is (d) 6

To explain: After the reaction, it will form [NI(H2O)6]^2- and 2Cl^– in which the former is the COORDINATION complex. There are six water molecules bound to Ni, which makes the secondary valence of Ni as 6.

The CORRECT choice is (b) Square planar

To elaborate: The CN of the metal ion is 4 because Cl^– is a unidentate ligand. The only possibility for the SHAPE of its coordination polyhedra is square planar or TETRAHEDRAL. From crystal FIELD SPLITTING diagram, it is known that [PtCl4]^2- is square planar.

The correct ANSWER is (B) False

The explanation is: In cationic complex ions, the metal is named same as element. On the other hand, in anionic complex ions, the name of the metal is ENDED with -ate.

Right choice is (a) 1:1

The explanation: Werner OBSERVED that ‘x’ mol of AgCl was precipitated per mole of CoCl3.4NH3 with excess silver nitrate. Currently, there are SEVEN GROUPS attached to the cobalt atom. For the secondary valence to be six, one of the CHLORIDE (x=1) has to be precipitated as AgCl, therefore 1:1 ELECTROLYTE.

Right choice is (a) paramagnetic

For explanation I would say: The oxidation state of FE in [Fe(CN)6]^3- ion is +3, which LEAVES it with FIVE unpaired electrons in 3d orbitals. Two of these pair up LEAVING one unpaired electron in 3d and six vacant orbitals to form d^2sp^3 hybridised octahedral inner orbital complex.

Right CHOICE is (a) coordination

The best explanation: There is only ONE complex ion and there is no possibility of a coordination ISOMER. The ionisation isomer is [CO(NH3)5(NO3)](NO3)(NO2) and the linkage isomer is [Co(NH3)5(ONO)](NO3)2.

Correct ANSWER is (d) no reaction

The best I can explain: The compound [Co(NH3)5Cl]SO4 dissociates into a COBALT complex ion and a sulphate ion when dissolved ion water. The sulphate ion does not react with silver ion. On the other hand, the ionisation isomer of [Co(NH3)5Cl]SO4, that is [Co(NH3)5(SO4)]Cl dissociates into cobalt complex ion and Cl ion which reacts with silver ion to precipitate AgCl.

The correct choice is (a) [Ag(NH3)2][Ag(CN)2]

Best explanation: Coordination isomerism takes PLACE when exchange of ligands happens between cationic and ANIONIC complex IONS having different metal ions. In the COMPOUND [Ag(NH3)2][Ag(CN)2], both the complexes have the same metal ion Ag^+, and hence does not have a coordination isomer.

Correct ANSWER is (b) Pentaamminenitrito-O-cobalt(III)

The explanation is: Nitrate is an ambidentate ligand and can BIND through either O or N ATOM. In this case, it is written as (ONO) which implies that it binds through O atom, hence giving it the NAME nitrito-O.

The correct option is (c) chelate

To explain: Unidentate LIGANDS use only ONE donor atom at a TIME. Didentate are POLYDENTATE ligands that have two donor ATOMS. An ambidentate ligand can bind through different donor atoms.

Correct answer is (b) False

To explain: The given compound is a coordination compound MADE of a COMPLEX ion, i.e., [Cu(NH3)4]^2+ which does not dissociate into its CONSTITUENT ions when dissolved. Hence, it is a complex salt and not a double salt.

The correct answer is (c) 5

Explanation: The solvate isomer of [Cr(H2O)6]CL3 that is grey-green in colour is [Cr(H2O)5CL]Cl2.H2O. This compound has 5 water molecules directly bonded to metal ion and one water MOLECULE as a free SOLVENT in the crystal lattice.

The CORRECT ANSWER is (c) 6

Explanation: The ion shown in the FIGURE is ethylenediaminetetraacetate which is a hexadentate ligand and can bind through its two N atoms or FOUR O atoms. Hence, its denticity is 6.