Complexes MCQ Quiz in मल्याळम - Objective Question with Answer for Complexes - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക
Last updated on Apr 8, 2025
Latest Complexes MCQ Objective Questions
Top Complexes MCQ Objective Questions
Complexes Question 1:
Cis and trans complexes of the type [PtA2X2] are distinguished by
Answer (Detailed Solution Below)
Complexes Question 1 Detailed Solution
The correct answer is Kurnakov test
Concept:-
- Coordination compounds and Isomerism: Coordination compounds can show different types of isomerism, depending on the arrangement of the ligands around the central metal atom. The [PtA2X2] compound is a square planar complex where 'cis' and 'trans' isomerism could occur, given A and X are different ligands.
- Cis and Trans Isomers: In cis isomers, the same type of ligands are adjacent to each other, while in trans isomers, the same type of ligands are opposite to each other.
- Chemical Tests: Different tests for distinguishing isomers are based on the unique chemical properties and behaviors of the compounds. These tests exploit the different reactivities or physical properties of the isomers.
-
The Chromyl Chloride test, Carbylamine test, and Ring test are also chemical tests, but they are not used to differentiate cis and trans isomers of Pt(II) complex. Instead, they're used to identify particular types of compounds or ions.
a. Chromyl Chloride Test: This test is used to detect chloride ions in a solution. It's not applicable in differentiating cis and trans isomers.
b. Carbylamine Test: This test is used to distinguish primary amines from secondary and tertiary amines. It doesn't apply to our problem of cis-trans isomer determination.
c. Ring Test: This test is also known as the confirmation test for nitrates, where a brown ring indicates the presence of nitrate ions. This too is not relevant to distinguishing cis and trans platinum complexes.
Explanation:-
Cis and trans isomers in coordination complexes refer to the spatial arrangement of the ligands attached to the central metal atom. In simple terms, "cis" configuration means the like ligands are on the same side of the metal complex, while "trans" configuration means the like ligands are opposite to each other.
The [PtA2X2] represents a square-planar complex of platinum where it can form both cis and trans isomers, depending upon whether similar ligands (A and A or X and X) are adjacent (cis) or opposite (trans).
The cis and trans isomers of these types of complexes can be distinguished using the Kurnakov test (also known as Kurnakov's reaction).
The Kurnakov test can distinguish between cis-platin ([Pt(NH3)2Cl2]) and trans-platin ([Pt(NH3)2Cl2]), where cis-platin reacts with thiourea to form a colorless solution, while trans-platin does not react.
So, the correct answer for distinguishing cis and trans complexes of the type [PtA2X2] is option 3) Kurnakov test.
Complexes Question 2:
The coordination number and oxidation state of Cr in K3 [Cr(C2O4)3] are respectively
Answer (Detailed Solution Below)
Complexes Question 2 Detailed Solution
Concept:
Coordination number -
- Coordination number is the number of coordinate bonds with which the ligands are bound to central ion.
- Ligand can be unidentate, bidentate and polydentate and ambidentate.
Oxidation state -
- Oxidation state also known as the oxidation number of an element is the number of positive or negative charges assigned to that element in a compound.
- It is the number of electrons lost or gained by an atom of that element.
Explanation:
Coordination number of Cr in K3 [Cr(C2O4)3]
- The oxalate (C2O4)2- is a bidentate ligand.
- Each oxalate ligand coordinate through two oxygen atoms.
- A total of three oxalate ligands are present in the coordination sphere with the Cr metal ion.
- Therefore, the coordination number of Cr is 6.
Oxidation state of Cr in K3 [Cr(C2O4)3]
- The overall charge on the complex is zero.
- The Sum of oxidation states of all elements in the complex is equal to 0.
- The charge on each oxalate ion is -2, so, the oxidation state of each oxalate ion is -2.
- Let the oxidation state of Cr is 'x'.
Calculation for the oxidation state of Cr -
K3 [Cr(C2O4)3]
+3 + x + 3(-2) = 0
x - 3 = 0
x = +3
Therefore, the oxidation state of Cr is +3.
Conclusion:
Therefore, The coordination number and oxidation state of Cr in K3 [Cr(C2O4)3] are respectively 6 and 3
Complexes Question 3:
The coordination number and oxidation state of Cr in K3 [Cr(C2O4)3] are respectively
Answer (Detailed Solution Below)
Complexes Question 3 Detailed Solution
Concept:
Coordination number -
- Coordination number is the number of coordinate bonds with which the ligands are bound to central ion.
- Ligand can be unidentate, bidentate and polydentate and ambidentate.
Oxidation state -
- Oxidation state also known as the oxidation number of an element is the number of positive or negative charges assigned to that element in a compound.
- It is the number of electrons lost or gained by an atom of that element.
Explanation:
Coordination number of Cr in K3 [Cr(C2O4)3]
- The oxalate (C2O4)2- is a bidentate ligand.
- Each oxalate ligand coordinate through two oxygen atoms.
- A total of three oxalate ligands are present in the coordination sphere with the Cr metal ion.
- Therefore, the coordination number of Cr is 6.
Oxidation state of Cr in K3 [Cr(C2O4)3]
- The overall charge on the complex is zero.
- The Sum of oxidation states of all elements in the complex is equal to 0.
- The charge on each oxalate ion is -2, so, the oxidation state of each oxalate ion is -2.
- Let the oxidation state of Cr is 'x'.
Calculation for the oxidation state of Cr -
K3 [Cr(C2O4)3]
+3 + x + 3(-2) = 0
x - 3 = 0
x = +3
Therefore, the oxidation state of Cr is +3.
Conclusion:
Therefore, The coordination number and oxidation state of Cr in K3 [Cr(C2O4)3] are respectively 6 and 3
Complexes Question 4:
The species that can have a trans-isomer is:
(en=ethane-1, 2-diamine, ox=oxalate)Answer (Detailed Solution Below)
Complexes Question 4 Detailed Solution
Concept:
Cis-Trans Isomers are isomers that differ in the arrangement of two ligands in square planar and octahedral geometry.
Cis isomers are isomers where the two ligands are 90 degrees apart from one another in relation to the central molecule. This is because Cis isomers have a bond angle of 90o, between two same atoms.
Trans isomers are isomers where the two ligands are on opposite sides in a molecule because trans isomers have a bond angle of 180o, between the two same atoms.
When naming cis or trans isomers, the name begins either with cis or trans, whichever applies, followed by a hyphen and then the name of a molecule.
Cis-trans Isomerism is possible with [Pt(en)2Cl2]2+
Only square planar and octahedral geometries can have cis or trans isomers.
(Dichloro(ethelyenediamine)platinum (II)) shows only optical isomerism. The other complexes do not show stereoisomerism.
Stereoisomerism, is also called as spatial isomerism, is a form of isomerism in which molecules have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in space. This contrasts with structural isomers which shares the same molecular formula, but the bond connections or their order differs.
Complexes Question 5:
Comprehension:
A d4 complex has an electronic configuration as
Answer (Detailed Solution Below)
Complexes Question 5 Detailed Solution
Concept:
Crystal Field Stabilization Energy -
- It is also abbreviated as CFSE.
- It is the amount of stabilization provided by the splitting of d-orbitals in two levels.
- It is denoted by Δo in the octahedral field and Δt in the tetrahedral field.
- If Δo > Pairing energy, the complex will be a low spin complex.
- If Δo < Pairing energy, the complex will be a high spin complex.
Explanation:
Given that the d4 complex has an electronic configuration as
For high spin complexes, Δo < Pairing energy.
For a high spin d4 complex splitting is -
CFSE = [-0.4× 3 + 0.6 × 1] Δo .
= - 0.6 Δo
Conclusion:
Thus, for a d4 complex has an electronic configuration as
Hence, the correct answer is option 1.
Complexes Question 6:
Comprehension:
The total number of electrons accommodated by Fe is [Fe(CO)5] are
Answer (Detailed Solution Below)
Complexes Question 6 Detailed Solution
Concept:
Effective Atomic Number (EAN) rule -
- The total no. of electrons present with the central metal atom in a coordination complex is called as the EAN.
- It is also known as the 18e- rule.
It is calculated by using the formula - T
Total electron on central metal = (Z-x) + 2nl,
where
- Z = atomic no. of metal
- x = oxidation state of metal
- n = number of ligands attached
- L = no. of coordinate bonds formed
Explanation:
The total number of electrons accommodated by Fe in [Fe(CO)5] is given by the Effective Atomic Number(EAN) rule.
According to the EAN rule,
Total electron on Fe = (Z-x) + 2nl
where
- Z = atomic no. of Fe
- x = oxidation state of Fe
- n = number of ligands attached
- L = no. of coordinate bonds formed
Oxidation no. of Fe in [Fe(CO)5] is 0.
Thus, EAN for Fe = (26-0) + 2 × 1 × 5 = 26+10 = 36
Hence, the total number of electrons accommodated by Fe = 36
Conclusion:
The total number of electrons accommodated by Fe in [Fe(CO)5] is 36.
Complexes Question 7:
Which sets of the d- orbitals are directly oriented towards the ligands in octahedral coordination compounds?
Answer (Detailed Solution Below)
Complexes Question 7 Detailed Solution
Correct answer: 4)
Concept:
- According to Crystal Field Theory, as a ligand approaches the metal ion, the electrons in the d-orbitals and those in the ligand repel each other due to repulsion between like charges.
- Thus the d-electrons closer to the ligands will have a higher energy than those further away which results in the d-orbitals splitting in energy.
- The dxy, dxz and dyz orbitals all lie between the bond axes.
- These three orbitals will be changed in energy only a little.
- These orbitals are more like non-bonding orbitals.
- These orbitals are sometimes called the "t2g" set of orbitals.
Explanation:
- d-subshell has five orbitals, i.e. dx2−y2,dz2,dxy,dxz and dyz.
- There are two d orbitals that will interact very strongly with these ligands: the dx2−y2, which lies directly on the x and y axes, and the dz2, which lies directly on the z-axis.
- Together, these two metal orbitals and the ligand orbitals that interact with them will form new bonding and antibonding molecular orbitals.
- The dx2−y2 and the dz2 orbitals lie along the bond axes.
- These two orbitals will be raised relatively high in energy.
- These orbitals are like antibonding levels.
- These orbitals are sometimes called the "eg" set of orbitals. The term "eg" comes from the mathematics of symmetry.
Conclusion:
Thus, dx2 - y2 and dz2 sets of the d- orbitals are directly oriented towards the ligands in octahedral coordination compounds.
Complexes Question 8:
Which of the following is isoelectric species?
Answer (Detailed Solution Below)
Complexes Question 8 Detailed Solution
CONCEPT:
Isoelectronic Species
- Two species are said to be isoelectronic if they have the same number of electrons.
- This includes atoms or ions, regardless of their chemical nature.
- To find the total number of electrons:
Total Electrons = Atomic Number ± Charge
EXPLANATION:
- Sn94−:
- Atomic number of Sn (in carbon Family)
- Charge = 4− → Add 4 electrons
- Total electrons = 9x4 + 4 = 40
- Bi95+:
- Atomic number of Bi (Nitrogen family)
- Charge = 95+ → Remove 5 electrons
- Total electrons = 9x5 - 5 = 40
Therefore, the isoelectronic species are Sn94-, Bi95+
Complexes Question 9:
Which metals of the following have the greatest tendency to form metal clusters?
Answer (Detailed Solution Below)
Complexes Question 9 Detailed Solution
CONCEPT:
Metal Clusters
- Metal clusters are chemical species in which two or more metal atoms are directly bonded together.
- These are commonly formed by transition metals that:
- Have partially filled d orbitals
- Exhibit multiple oxidation states
- Show a high tendency for metal–metal bonding
- Clusters can be stabilized by ligands like CO, halides, etc.
EXPLANATION:
- Niobium (Nb), Molybdenum (Mo), and Technetium (Tc) belong to the middle of the d-block (groups 5–7).
- These elements have a high tendency to form stable metal–metal bonds, especially in their carbonyl and halide complexes.
- Examples include:
- [Nb6Cl12]²⁻: a known niobium cluster
- [Mo6Cl14]²⁻: molybdenum cluster with octahedral Mo–Mo bonding
- Tc carbonyl clusters: like [Tc2(CO)10], [Tc6(CO)15]
Therefore, the metals with the greatest tendency to form metal clusters are:
Nb, Mo, Tc
Complexes Question 10:
Which of the following metal carbonyls doesn’t exhibit EAN rule?
Answer (Detailed Solution Below)
Complexes Question 10 Detailed Solution
CONCEPT:
Effective Atomic Number (EAN) Rule
- The Effective Atomic Number (EAN) rule states that a metal in a complex tends to achieve an electron configuration equal to the nearest noble gas by including its valence electrons and the electrons donated by the ligands.
- The EAN is calculated using the formula:
EAN = Z - O + d + 2n
- Z = Atomic number of the metal atom
- O = Oxidation state of the metal
- d = Number of d-electrons
- n = Number of ligands (each ligand contributes 2 electrons)
EXPLANATION:
- Fe(CO)5:
- Z = 26 (atomic number of Fe)
- EAN = 26 + (2 × 5) = 26 + 10 = 36 (noble gas configuration of Kr)
- Mn(CO)5:
- Z = 25 (atomic number of Mn)
- EAN = 25 + (2 × 5) = 25 + 10 + 7 = 35
- The EAN does not match the nearest noble gas configuration (36), so it does not follow the EAN rule.
- Cr(CO)6:
- Z = 24 (atomic number of Cr)
- EAN = 24 + (2 × 6) = 24 + 12 = 36 (noble gas configuration of Kr)
- Ni(CO)4:
- Z = 28 (atomic number of Ni)
- EAN = 28 + (2 × 4) = 28 + 8 = 36 (noble gas configuration of Kr)
Therefore, Mn(CO)5 (Option 2) does not exhibit the EAN rule as its total EAN is 35, which does not match the noble gas configuration.