Coordination Compounds

01

PYQ 2014

medium

chemistry ID: mht-cet-

What is the coordination number of the central metal ion in ?

1

3

2

5

3

4

4

6

02

PYQ 2017

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chemistry ID: mht-cet-

Which of following coordinate complexes is an exception to rule ? (Given At. No. Pt = 78, Fe = 26, Zn = 30, Cu = 29)

1

2

3

4

03

PYQ 2018

medium

chemistry ID: mht-cet-

What is the number of donar atoms in dimethylglyoximato ligand?

1

1

2

2

3

3

4

4

04

PYQ 2019

medium

chemistry ID: mht-cet-

Which among the following is a neutral complex?

1

2

3

4

05

PYQ 2019

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chemistry ID: mht-cet-

According to Werner?s theory the geometry of the complex is determined by

1

only from the primary valence in space

2

number and position of the primary valences in space

3

number and position of the secondary valences in space

4

only from the position of secondary valence in space

06

PYQ 2020

medium

chemistry ID: mht-cet-

What is the oxidation number of Fe in K [Fe(CN)]?

1

-6

2

-3

3

+3

4

+6

07

PYQ 2020

medium

chemistry ID: mht-cet-

Which among the following complexes is NOT a heteroleptic complex?

1

2

3

4

08

PYQ 2020

medium

chemistry ID: mht-cet-

Identify the ionic charge and magnetic nature respectively of manganate ion.

1

-1, Diamagnetic

2

-2, Diamagnetic

3

-2, Paramagnetic

4

-1, Paramagnetic

09

PYQ 2020

medium

chemistry ID: mht-cet-

Which among the following compounds has the highest boiling point?

1

CH -CH -CH -OH

2

CH -CH -COCH

3

CH -CH -COOH

4

CH -CH -CH -CHO

10

PYQ 2020

medium

chemistry ID: mht-cet-

Which among the following complexes carries no net charge?

1

2

3

4

11

PYQ 2020

medium

chemistry ID: mht-cet-

Blurring of vision is a side effect caused by the use of:

1

Antibiotics

2

Antacids

3

Tranquilizers

4

Analgesics

12

PYQ 2020

medium

chemistry ID: mht-cet-

What is the oxidation state and coordination number of platinum respectively in

1

and

2

and

3

and

4

and

13

PYQ 2020

medium

chemistry ID: mht-cet-

Identify product B in the following reaction. Phenol A B

1

Anisole

2

Iodobenzene

3

Toluene

4

Phenetole

14

PYQ 2020

medium

chemistry ID: mht-cet-

Which of the following metals is refined by using a tungsten filament for heating in a vessel so that the pure metal deposits on the filament?

1

Cu

2

Zr

3

Al

4

Ni

15

PYQ 2020

medium

chemistry ID: mht-cet-

In Merck’s method, is obtained from

1

2

3

4

16

PYQ 2020

medium

chemistry ID: mht-cet-

What type of geometry and magnetic behaviour is found in compound [NiCl] ? (Atomic no. Ni = 28)}

1

Square planar and Paramagnetic

2

Tetrahedral and paramagnetic

3

Pyramidal and diamagnetic

4

Square planar and paramagnetic

17

PYQ 2020

medium

chemistry ID: mht-cet-

What type of isomerism is present between (I) [Cr(H O)]Cl and (II) [Cr(H O) Cl]Cl H O?

1

Ionisation

2

Coordination

3

Hydrate

4

Linkage

18

PYQ 2020

medium

chemistry ID: mht-cet-

Which among the following is NOT paramagnetic in nature?

1

Benzene

2

Oxygen

3

Fe

4

Cu

19

PYQ 2020

medium

chemistry ID: mht-cet-

$How many donor groups are present in dimethyl glyoximato?$

1

$Three$

2

$Two$

3

$Four$

4

$One$

Official Solution

Correct Option: $(2)$

$Step 1: Understanding the structure of dimethyl glyoximato. Dimethyl glyoximato is a bidentate ligand, meaning it has two donor groups. These groups are typically the nitrogen and oxygen atoms in the structure, which can coordinate to a metal center. Step 2: Analyzing the options. (A) Three: Incorrect. Dimethyl glyoximato has only two donor groups. (B) Two: Correct. The two donor groups are the nitrogen and oxygen atoms. (C) Four: Incorrect. Dimethyl glyoximato only has two donor groups, not four. (D) One: Incorrect. There are two donor groups in dimethyl glyoximato. Step 3: Conclusion. The correct answer is (B) Two, as dimethyl glyoximato has two donor groups that can bind to a metal center.$

20

PYQ 2020

medium

chemistry ID: mht-cet-

$Which of the following is a property of coordination compound and not of double salt?$

1

$These dissociate into their constituent ions when dissolved in water.$

2

$These show entirely different properties from their constituent ions.$

3

$These lose their identity in aqueous solution.$

4

$Aqueous solution of these gives the tests of all constituent ions.$

Official Solution

Correct Option: $(2)$

$Step 1: Understanding the properties. Coordination compounds are complex compounds that consist of a central metal atom bonded to ligands. These compounds exhibit distinct properties from their constituent ions, which is a defining feature of coordination compounds. Step 2: Analyzing the options. (A) These dissociate into their constituent ions when dissolved in water: This is true for salts, but not specific to coordination compounds. (B) These show entirely different properties from their constituent ions: Correct. Coordination compounds have distinct properties from the individual ions they contain due to the metal-ligand bonds. (C) These lose their identity in aqueous solution: Incorrect. Coordination compounds retain their identity in solution. (D) Aqueous solution of these gives the tests of all constituent ions: Incorrect. Coordination compounds do not necessarily show tests for all their constituent ions. Step 3: Conclusion. The correct answer is (B) These show entirely different properties from their constituent ions.$

21

PYQ 2020

medium

chemistry ID: mht-cet-

$Which of the following compounds is obtained when is treated with excess in presence of pyridine?$

1

2

3

4

Official Solution

Correct Option: $(1)$

$Step 1: Nature of ethylamine. Ethylamine is a primary amine and contains an active hydrogen atom attached to nitrogen. Step 2: Reaction with excess acetic anhydride. When treated with excess acetic anhydride in presence of pyridine, both hydrogen atoms of the amine group are replaced by acetyl groups. Step 3: Formation of diacetyl derivative. This leads to the formation of N,N-diacetyl ethylamine. Step 4: Conclusion. Hence, the product formed is .$

22

PYQ 2020

medium

chemistry ID: mht-cet-

$Identify the precipitate and its quantity obtained when 1 mole of aqueous solution of Tetraammine dichloroplatinum(IV) bromide is treated with aqueous silver nitrate in excess.$

1

$Two moles of silver chloride$

2

$Two moles of silver chloride and one mole of silver bromide$

3

$One mole of silver bromide$

4

$Two moles of silver bromide$

Official Solution

Correct Option: $(4)$

$Step 1: Understanding the reaction. When Tetraammine dichloroplatinum(IV) bromide () reacts with excess silver nitrate (AgNO₃), it forms a precipitate. The bromide ions (Br⁻) from the platinum complex react with silver ions (Ag⁺) to form silver bromide (AgBr) as a precipitate. Since two bromide ions are present in the complex, two moles of silver bromide are formed. Step 2: Analyzing the options. (A) Two moles of silver chloride: Incorrect. This is not the product because chloride ions are not in excess here; bromide ions react. (B) Two moles of silver chloride and one mole of silver bromide: Incorrect. Only silver bromide forms as the precipitate, not silver chloride. (C) One mole of silver bromide: Incorrect. Two moles of silver bromide will be formed due to two bromide ions in the platinum complex. (D) Two moles of silver bromide: Correct — Two moles of silver bromide are formed, one from each bromide ion in the complex. Step 3: Conclusion. The correct answer is (D) Two moles of silver bromide, as two bromide ions react with silver ions to form two moles of silver bromide.$

23

PYQ 2020

medium

chemistry ID: mht-cet-

$Which among the following pairs of elements in their respective oxidation states will have the same value of effective magnetic moment?$

1

$Zn²⁺ and Cr³⁺$

2

$Ni²⁺ and Ti³⁺$

3

$Cr³⁺ and Co²⁺$

4

$Sc³⁺ and Ti³⁺$

Official Solution

Correct Option: $(3)$

$Step 1: Understanding effective magnetic moment. The effective magnetic moment () depends on the number of unpaired electrons. Elements with the same number of unpaired electrons will have the same effective magnetic moment. To calculate this, we use the formula: where is the number of unpaired electrons. Step 2: Analyzing the options. (A) Zn²⁺ and Cr³⁺: Incorrect. Zn²⁺ has no unpaired electrons (d¹⁰ configuration), while Cr³⁺ has 3 unpaired electrons. They will not have the same magnetic moment. (B) Ni²⁺ and Ti³⁺: Incorrect. Ni²⁺ has 2 unpaired electrons, while Ti³⁺ has 1 unpaired electron. They will not have the same magnetic moment. (C) Cr³⁺ and Co²⁺: Correct — Both Cr³⁺ (d⁵) and Co²⁺ (d⁷) have 3 unpaired electrons, which results in the same effective magnetic moment. (D) Sc³⁺ and Ti³⁺: Incorrect. Sc³⁺ has no unpaired electrons (d⁰), while Ti³⁺ has 1 unpaired electron. They will not have the same magnetic moment. Step 3: Conclusion. The correct answer is (C) Cr³⁺ and Co²⁺, as both ions have the same number of unpaired electrons, leading to the same effective magnetic moment.$

24

PYQ 2020

medium

chemistry ID: mht-cet-

$Identify the coordinate complex having ambidentate ligand from the following.$

1

$Diammine silver (I) chloride$

2

$Sodium hexanitrito-N-cobaltate (III)$

3

$Tetraaquadichlorochromium (III) chloride$

4

$Barium tetrachlorocuprate (II)$

Official Solution

Correct Option: $(2)$

$Step 1: Define ambidentate ligand. An ambidentate ligand is a ligand that can coordinate to a central metal atom through two different donor atoms, but only one at a time. Step 2: Identify ambidentate ligands. Common ambidentate ligands include,, . Step 3: Analyze the options. (A) Diammine silver (I) chloride contains, which is a monodentate ligand. (B) Sodium hexanitrito-N-cobaltate (III) contains the nitrito ligand, which is ambidentate and can coordinate through nitrogen or oxygen. (C) Tetraaquadichlorochromium (III) chloride contains aqua and chloro ligands, both monodentate. (D) Barium tetrachlorocuprate (II) contains chloride ligands, which are monodentate. Step 4: Conclusion. The complex containing an ambidentate ligand is sodium hexanitrito-N-cobaltate (III).$

25

PYQ 2020

medium

chemistry ID: mht-cet-

$Which among the following is a heaviest isotope of water?$

1

2

3

4

Official Solution

Correct Option: $(4)$

$Step 1: Understanding isotopes of water. Isotopes of water differ in the isotopic composition of hydrogen (H, D, T) and oxygen (O, O, O). Heavier isotopes contain nuclei with greater mass numbers. Step 2: Comparison of given options. Tritium (T) is the heaviest isotope of hydrogen, and O is the heaviest naturally occurring isotope of oxygen among the given options. Step 3: Identifying the heaviest combination. A molecule containing two tritium atoms and one O atom will have the highest molecular mass. Step 4: Conclusion. Therefore, the heaviest isotope of water is (D)}.$

26

PYQ 2020

medium

chemistry ID: mht-cet-

$What is the type of hybridisation and the geometry respectively found in ?}$

1

$and pentagonal bipyramidal$

2

$and octahedral$

3

$and trigonal bipyramidal$

4

$and pentagonal bipyramidal$

Official Solution

Correct Option: $(2)$

$Step 1: Oxidation state of cobalt. In, each fluoride ion has a charge of . So, cobalt is in +3 oxidation state. Step 2: Nature of ligand. Fluoride () is a weak field ligand and does not cause pairing of electrons. Step 3: Hybridisation and geometry. Due to weak field ligands, outer orbital complex is formed using hybridisation, resulting in octahedral geometry. Step 4: Conclusion. Hence, the correct answer is (B) and octahedral .$

27

PYQ 2020

medium

chemistry ID: mht-cet-

$Identify the type of drug used to reduce pain and irritation of stomach?$

1

$Tranquilizer$

2

$Antibiotic$

3

$Antiseptic$

4

$Antacid$

Official Solution

Correct Option: $(4)$

$Step 1: Cause of stomach pain and irritation. Pain and irritation in the stomach are generally caused by excess secretion of hydrochloric acid in the gastric juice. Step 2: Role of antacids. Antacids are substances that neutralize excess stomach acid, thereby relieving pain, irritation, and discomfort. Step 3: Elimination of other options. Tranquilizers affect the nervous system, antibiotics kill bacteria, and antiseptics prevent infection on wounds. None of these neutralize stomach acid. Step 4: Conclusion. Thus, the correct answer is (D) Antacid .$

28

PYQ 2020

medium

chemistry ID: mht-cet-

$What is the value of primary valence of Co in CoCl ?$

1

$2$

2

$4$

3

$3$

4

$1$

Official Solution

Correct Option: $(3)$

$Step 1: Understanding primary valence. Primary valence, according to Werner's coordination theory, corresponds to the oxidation state of the central metal atom. It is satisfied by negative ions and is ionisable in nature. Step 2: Oxidation state of cobalt in CoCl . In cobalt(III) chloride, cobalt is bonded to three chloride ions, each having a charge of . To balance the total negative charge, cobalt must have an oxidation state of . Step 3: Relation to primary valence. Since the oxidation state of cobalt in CoCl is, the primary valence of cobalt is also 3. Step 4: Conclusion. Hence, the correct answer is (C) 3 .$

29

PYQ 2020

medium

chemistry ID: mht-cet-

$Which polymer from the following is used as synthetic leather?$

1

$Bakelite$

2

$PVC$

3

$Polystyrene$

4

$Polythene$

Official Solution

Correct Option: $(2)$

$Step 1: Understanding synthetic leather. Synthetic leather is often made from polymers such as PVC (polyvinyl chloride). PVC is commonly used for making synthetic leather due to its durability and flexibility. Step 2: Analyzing the options. (A) Bakelite: Bakelite is a thermosetting plastic and is not used as synthetic leather. (B) PVC: Correct — PVC is widely used in synthetic leather. (C) Polystyrene: Polystyrene is a rigid plastic, not used for synthetic leather. (D) Polythene: Polythene is a low-density polymer, and it is not typically used for synthetic leather. Step 3: Conclusion. The correct answer is (B) PVC, as it is commonly used in synthetic leather.$

30

PYQ 2020

medium

chemistry ID: mht-cet-

$What is the effective atomic number of Fe in [Fe(CN)] (At. no. of Fe = 26)?$

1

$34$

2

$26$

3

$36$

4

$35$

Official Solution

Correct Option: $(3)$

$Step 1: Understanding the Effective Atomic Number (EAN). The effective atomic number (EAN) is calculated by adding the atomic number of the central metal ion to the number of electrons donated by the ligands. In this case, Fe has an atomic number of 26. The cyanide ligand (CN) donates 2 electrons. Since there are six cyanide ions, the total number of electrons donated by the ligands is . The EAN is thus: Step 2: Analyzing the options. (A) 34: Incorrect. This is not the correct EAN value. (B) 26: Incorrect. This is the atomic number of Fe, not the effective atomic number. (C) 36: Correct. The EAN is 36 for the [Fe(CN)] complex. (D) 35: Incorrect. This is not the correct EAN value. Step 3: Conclusion. The effective atomic number is 36, corresponding to option (C) .$

31

PYQ 2020

medium

chemistry ID: mht-cet-

$Which among the following coordination compounds does not have coordination number equal to the number of ligands?$

1

$[Pt(NH)]$

2

$[Co(en)]$

3

$[Cu(NH)]$

4

$[Co(NH)]$

Official Solution

Correct Option: $(2)$

$Step 1: Understanding the Concept of Coordination Number. In coordination chemistry, the coordination number is the number of bonds formed between the metal and the ligands. Generally, the coordination number is equal to the number of ligands when each ligand binds through a single atom. However, in some cases, ligands like ethylenediamine (en), which is a bidentate ligand, bind through two atoms, so the coordination number will be different from the number of ligands. Step 2: Analyzing the Options. (A) [Pt(NH)] : Correct. This compound has a coordination number of 6, which is equal to the number of ligands (6 NH molecules). (B) [Co(en)] : Correct. This compound has a coordination number of 6 because each ethylenediamine (en) ligand binds through two atoms, so the coordination number is 2 \times 3 = 6, but there are 3 ligands, which are different. (C) [Cu(NH)] : Correct. This compound has a coordination number of 4, which matches the number of ligands (4 NH molecules). (D) [Co(NH)] : Correct. This compound has a coordination number of 6, which is equal to the number of ligands (6 NH molecules). Step 3: Conclusion. The correct answer is (B) [Co(en)], as it has a coordination number of 6, but only 3 ligands.$

32

PYQ 2020

medium

chemistry ID: mht-cet-

$Which among the following group-15 elements does NOT react with concentrated sulfuric acid?$

1

$Phosphorus$

2

$Arsenic$

3

$Nitrogen$

4

$Antimony$

Official Solution

Correct Option: $(3)$

$Step 1: Understanding the reactivity. Group 15 elements generally react with concentrated sulfuric acid, but nitrogen is an exception due to its strong bond and inertness in this reaction. Other elements like phosphorus, arsenic, and antimony react to form respective oxides and other products. Step 2: Analyzing the options. (A) Phosphorus: Phosphorus reacts with concentrated sulfuric acid to form phosphoric acid and phosphorous acid. (B) Arsenic: Arsenic reacts with concentrated sulfuric acid, forming arsenic acid. (C) Nitrogen: Nitrogen does not react with concentrated sulfuric acid under normal conditions. (D) Antimony: Antimony reacts with concentrated sulfuric acid, forming antimony pentachloride. Step 3: Conclusion. The correct answer is (C) Nitrogen, as it does not react with concentrated sulfuric acid.$

33

PYQ 2020

medium

chemistry ID: mht-cet-

$Identify the element having the highest enthalpy of atomization from the following.$

1

$Cu (Z=29)$

2

$Fe (Z=26)$

3

$Zn (Z=30)$

4

$Sc (Z=21)$

Official Solution

Correct Option: $(2)$

$Step 1: Understanding enthalpy of atomization. The enthalpy of atomization refers to the amount of energy required to break a bond in a molecule to form individual atoms in the gas phase. Iron (Fe) has the highest enthalpy of atomization among the given elements due to its metallic bonding and structure. Step 2: Analyzing the options. (A) Cu: Copper has a relatively low enthalpy of atomization compared to iron. (B) Fe: Iron has the highest enthalpy of atomization among the listed elements due to its bonding. (C) Zn: Zinc has a moderate enthalpy of atomization but is lower than iron. (D) Sc: Scandium has a lower enthalpy of atomization compared to iron. Step 3: Conclusion. The correct answer is (B) Fe (Z=26) as it has the highest enthalpy of atomization.$

34

PYQ 2020

medium

chemistry ID: mht-cet-

$A compound has fcc structure. If density of unit cell is 3.4 g cm, what is the edge length of unit cell? (Molar mass = 98-99)}$

1

$7.783 \AA$

2

$5.783 \AA$

3

$8.780 \AA$

4

$6.083 \AA$

Official Solution

Correct Option: $(2)$

$Step 1: Using the formula for edge length. For a compound with an fcc (face-centered cubic) structure, the relationship between the density ( ), molar mass ( ), Avogadro’s number ( ), and edge length ( ) is given by the formula: Where for fcc structure. We can rearrange this to solve for , the edge length: Where: - (for fcc structure) - - - Step 2: Calculation. Substitute the values into the equation: After performing the calculation, we find that . Step 3: Conclusion. The correct answer is (B) 5.783 \AA, which corresponds to the calculated edge length.$

35

PYQ 2020

medium

chemistry ID: mht-cet-

$What is the type of magnetic behavior and geometry respectively in Cuprammonium sulfate (atomic no. of Cu = 29)?$

1

$Paramagnetic and tetrahedral$

2

$Diamagnetic and pyramidal$

3

$Diamagnetic and tetrahedral$

4

$Paramagnetic and square planar$

Official Solution

Correct Option: $(4)$

$Step 1: Understanding magnetic behavior and geometry. Cuprammonium sulfate contains Cu ions, which are paramagnetic due to the presence of unpaired electrons. The geometry of the complex is square planar due to the coordination of ligands with the central Cu ion. Step 2: Analyzing the options. (A) Paramagnetic and tetrahedral: Tetrahedral geometry is not observed for this complex. (B) Diamagnetic and pyramidal: The complex is paramagnetic, not diamagnetic. (C) Diamagnetic and tetrahedral: The complex is paramagnetic, not diamagnetic. (D) Paramagnetic and square planar: This is correct. The complex is paramagnetic with square planar geometry. Step 3: Conclusion. The correct answer is (D) Paramagnetic and square planar .$

36

PYQ 2020

medium

chemistry ID: mht-cet-

$Identify the formula of potassium trioxalato aluminate (III).$

1

$K [Al(C O)]$

2

$K Al(C O)$

3

$Al [K (C O)]$

4

$K [Al(C O)]$

Official Solution

Correct Option: $(4)$

$Step 1: Understanding the complex. Potassium trioxalato aluminate (III) consists of potassium ions (K) and the complex ion [Al(C O)], where the aluminum ion is coordinated with three oxalate (C O) ligands. The formula is K [Al(C O)]. Step 2: Analyzing the options. (A) K [Al(C O)]: Incorrect — The charge on the complex would not balance. (B) K Al(C O) : Incorrect — The correct formula should have the complex ion in brackets. (C) Al [K (C O)]: Incorrect — This formula does not represent the correct stoichiometry of the ions. (D) K [Al(C O)]: Correct — This is the correct formula for potassium trioxalato aluminate (III). Step 3: Conclusion. The correct answer is (D) K [Al(C O)] .$

37

PYQ 2020

medium

chemistry ID: mht-cet-

$Which among the following complexes is a homoleptic and cationic in nature?$

1

$[CoCl (en)]Cl$

2

$[Fe(H O)]Cl$

3

$K[Ag(CN)]$

4

$[Fe(CO)]$

Official Solution

Correct Option: $(2)$

$Step 1: Understanding homoleptic and cationic complexes. A homoleptic complex is one in which all the ligands are the same. A cationic complex has a positive charge. The complex [Fe(H O)]Cl is homoleptic (all water ligands) and cationic (having a positive charge). Step 2: Analyzing the options. (A) [CoCl (en)]Cl: This is a heteroleptic complex (with both chloride and ethylenediamine as ligands) and is not cationic. (B) [Fe(H O)]Cl : Correct — This is homoleptic and cationic in nature. (C) K[Ag(CN)]: This is a heteroleptic complex with cyanide and not cationic. (D) [Fe(CO)]: This is homoleptic, but it is neutral, not cationic. Step 3: Conclusion. The correct answer is (B) [Fe(H O)]Cl, as it is homoleptic and cationic.$

38

PYQ 2020

medium

chemistry ID: mht-cet-

$Which statement from the following is true for a complex hexammine cobalt(III) chloride?$

1

$In this coordination number of cobalt is 9$

2

$In this oxidation state of cobalt is$

3

$It is a heteroleptic complex$

4

$It is an anionic complex$

Official Solution

Correct Option: $(2)$

$Step 1: Write the formula of the complex. Hexammine cobalt(III) chloride has the formula . Step 2: Determine coordination number. Six ammonia ligands are attached to cobalt, so coordination number is 6, not 9. Step 3: Determine oxidation state. Ammonia is a neutral ligand and three chloride ions are present outside the coordination sphere. Hence, oxidation state of cobalt is . Step 4: Nature of complex. All ligands are same (homoleptic) and the complex ion is cationic, not anionic. Step 5: Conclusion. Thus, the correct statement is that the oxidation state of cobalt is .$

39

PYQ 2020

medium

chemistry ID: mht-cet-

$Identify the gas used in gas chromatography.$

1

$Helium$

2

$Argon$

3

$Hydrogen$

4

$Neon$

Official Solution

Correct Option: $(2)$

$Step 1: Understanding gas chromatography. Gas chromatography (GC) is an analytical technique used to separate and analyze gases or volatile compounds. In GC, an inert gas is used as the carrier gas. Argon is often preferred due to its inert nature. Step 2: Analyzing the options. (A) Helium: Helium is commonly used as a carrier gas in gas chromatography due to its low molecular weight and inertness. (B) Argon: Correct — Argon is also used in gas chromatography, although helium is more common. (C) Hydrogen: Hydrogen is used in some types of gas chromatography, but it is not as inert as helium or argon. (D) Neon: Neon is not commonly used as a carrier gas in gas chromatography. Step 3: Conclusion. The correct answer is (B) Argon, though helium is more commonly used.$

40

PYQ 2020

medium

chemistry ID: mht-cet-

$Which from the following complexes, the central metal ion does NOT obey the EAN rule? (Atomic number = Pt = 78, Cu = 29, Zn = 30, Fe = 26)$

1

2

3

4

Official Solution

Correct Option: $(2)$

$Step 1: Understanding the EAN rule. The Effective Atomic Number (EAN) rule states that the total number of electrons around the central metal atom/ion in a complex should be equal to the atomic number of the nearest noble gas. Step 2: Analyzing the options. (A) :} This follows the EAN rule, as Zn has 30 electrons and the complex provides 30 electrons around the metal. (B) :} This does not follow the EAN rule as copper in this complex would not achieve a noble gas configuration (only 18 electrons). (C) :} This follows the EAN rule with platinum achieving 36 electrons. (D) :} This follows the EAN rule as well. Step 3: Conclusion. The correct answer is (B)}.$

41

PYQ 2020

medium

chemistry ID: mht-cet-

$Identify the oxidation state of chromium in .$

1

2

3

4

Official Solution

Correct Option: $(1)$

$Step 1: Determine the charge on the complex ion. Since there are three ions, the charge on the complex ion is . Step 2: Assign charges to ligands. Each oxalate ion has a charge of . Total charge from ligands . Step 3: Calculate oxidation state of chromium. Let oxidation state of Cr be : Step 4: Conclusion. The oxidation state of chromium is .$

42

PYQ 2020

medium

chemistry ID: mht-cet-

$Which ligand among the following has the highest splitting power of d-orbitals of central metal ion?$

1

$S$

2

$OH$

3

$NCS$

4

$CO$

Official Solution

Correct Option: $(4)$

$Step 1: Understanding ligand field theory. Ligand field theory explains how ligands influence the splitting of d-orbitals in a metal complex. Ligands that produce a strong field cause a large splitting of the d-orbitals. Step 2: Analyzing the options. (A) S : Sulfide anion is a strong field ligand, but not the strongest compared to CO. (B) OH : Hydroxide is a weak field ligand, causing smaller splitting of d-orbitals. (C) NCS: Thiocyanate is also a weak to moderate field ligand, causing intermediate splitting. (D) CO: Carbon monoxide is a very strong field ligand and causes the maximum splitting of d-orbitals in a metal complex. It is known for its high splitting power. Step 3: Conclusion. The correct answer is (D) CO, as it has the highest splitting power due to its strong field strength.$

43

PYQ 2022

easy

chemistry ID: mht-cet-

$Identify correct pair of properties of [Co(NH 3) 6] 3+ complex ion.$

1

$Low spin, paramagnetic$

2

$High spin, diamagnetic$

3

$Low spin, diamagnetic$

4

$High spin, paramagnetic$

Official Solution

Correct Option: $(3)$

$Solution: The complex ion given is [Co(NH 3) 6] 3+ . Step 1: Determine the oxidation state of cobalt (Co): Ammonia (NH 3) is a neutral ligand. So, the oxidation state of Co is +3. Step 2: Electronic configuration of Co 3+ Atomic number of Co = 27 \to Electronic configuration = [Ar] 3d 7 4s 2 Co 3+ \to [Ar] 3d 6 Step 3: Nature of ligand and geometry NH 3 is a strong field ligand (according to the spectrochemical series), which causes pairing of electrons. This leads to formation of a low spin complex. Step 4: Magnetism Due to pairing of electrons in the 3d orbital (caused by the strong ligand NH 3), all electrons are paired in Co 3+ \to no unpaired electrons \to diamagnetic Conclusion: The correct properties are Low spin, Diamagnetic . Correct Answer: Option 3: Low spin, diamagnetic$

44

PYQ 2022

medium

chemistry ID: mht-cet-

$Identify anionic complex from following$

1

$Bis (ethylene diamine) dithiocyanatoplatinum (IV)$

2

$Pentaamminecarbonatocobalt (III) chloride$

3

$Pentacarbonyliron (0)$

4

$Sodiumhexanitrocobaltate (III)$

Official Solution

Correct Option: $(4)$

$Correct Answer: (4) Sodium hexanitrocobaltate(III) Solution: To determine the anionic complex, we classify coordination compounds based on the net charge of the complex ion: Cationic complex: Positively charged complex ion Neutral complex: No net charge Anionic complex: Negatively charged complex ion Let’s evaluate each option: (1) Bis(ethylenediamine)dithiocyanatoplatinum(IV) - Ethylenediamine is neutral, dithiocyanate is anionic - Platinum is +4; overall charge is balanced \to Neutral complex \to Not anionic (2) Pentaamminecarbonatocobalt(III) chloride - Ammine is neutral, carbonate is -2 - Cobalt is +3, and there's an external Cl⁻ ion \to Complex is cationic \to Not anionic (3) Pentacarbonyliron(0) - CO is a neutral ligand - Iron is in 0 oxidation state \to Neutral complex \to Not anionic (4) Sodium hexanitrocobaltate(III) - Sodium (Na⁺) is outside the complex - Complex: [Co(NO 2) 6] 3- \to Negatively charged complex ion \to This is the anionic complex$

45

PYQ 2023

medium

chemistry ID: mht-cet-

$Identify the one differentiating characteristics between Homoleptic complex and Heteroleptic complex.$

Official Solution

Correct Option: $(1)$

$The differentiating characteristic between homoleptic complexes and heteroleptic complexes lies in the nature of the ligands involved. Homoleptic Complex: In a homoleptic complex, all the ligands attached to the central metal ion are of the same type. This means that the complex consists entirely of one kind of ligand. For example, in the complex, all the ligands are carbon monoxide (CO) molecules. This type of complex is typically formed when a central metal ion coordinates with several molecules or ions of the same ligand. Example of Homoleptic Complex: In, the nickel ion () is surrounded by four carbon monoxide (CO) ligands. All of these ligands are identical, making it a homoleptic complex. Heteroleptic Complex: In a heteroleptic complex, different types of ligands are attached to the central metal ion. The ligands may vary in their chemical composition or coordination number. These complexes typically contain a mixture of various ligands, such as anions, neutral molecules, or a combination of both. The ligands in heteroleptic complexes can be of different types, making these complexes more versatile in their chemical interactions. Example of Heteroleptic Complex: In the complex, the nickel ion () is coordinated with two carbon monoxide (CO) ligands and two ethylenediamine (en) ligands. Here, CO and ethylenediamine are two different types of ligands, making this a heteroleptic complex. Summary: Therefore, the distinguishing characteristic between homoleptic and heteroleptic complexes is that homoleptic complexes have ligands of the same type, while heteroleptic complexes have different types of ligands.$

46

PYQ 2024

easy

chemistry ID: mht-cet-

$Which of the following is not a neutral ligand?$

1

2

3

4

Official Solution

Correct Option: $(3)$

$In coordination chemistry, ligands are classified based on their charge as either neutral or charged. A neutral ligand has no overall charge, while a charged ligand carries either a positive or negative charge. Step 1: Analyze Each Option. - (Water): Water is a neutral ligand. It does not carry any charge, making it a neutral ligand. - (Ammonia): Ammonia is another example of a neutral ligand. It has no net charge. - (Carbon monoxide): Carbon monoxide is also a neutral ligand. It is commonly used as a ligand in transition metal complexes and does not have a charge. - (Nitrito group): The nitrito group is negatively charged, making it an anionic ligand, not a neutral one. Step 2: Identify the Non-neutral Ligand. The ligand is a charged ligand (it carries a negative charge) and is thus not neutral. Therefore, it is the correct answer for the ligand that is not neutral. Conclusion: The ligand is not a neutral ligand, so the correct answer is .$

47

PYQ 2024

medium

chemistry ID: mht-cet-

$The IUPAC name for the complex is$

1

2

3

4

Official Solution

Correct Option: $(2)$

$The complex consists of: : A nitrito ligand coordinated via the oxygen atom (denoted as "nitrito-O"), : Neutral ammine ligands, : Counter ions. To determine the oxidation state of cobalt, use the following calculation: Therefore, the IUPAC name of the complex is:$

48

PYQ 2024

medium

chemistry ID: mht-cet-

$The IUPAC name of the complex ion formed when gold dissolves in aqua regia is:$

1

2

3

4

Official Solution

Correct Option: $(3)$

$When gold (Au) dissolves in aqua regia, a mixture of concentrated nitric acid and hydrochloric acid, it reacts to form a complex ion. The process is represented by the following reaction: The complex ion formed is, where chlorido ions (Cl-) are coordinated to the central metal ion (gold, Au). This is a typical coordination compound. Step 1: Identify the Oxidation State of Gold. To determine the oxidation state of gold (Au) in the complex ion, we can use the following steps: Let the oxidation state of gold be . In the chloride ligands, chlorine has an oxidation state of . So, for the complex ion: Simplifying: Thus, the oxidation state of gold in this complex is . Step 2: Determine the IUPAC Name. The complex ion formed is . According to **IUPAC naming conventions: - The prefix tetra- is used for four chloride (Cl) ligands. - The central metal, gold (Au), is named as aurate. - The oxidation state of the metal, which is, is indicated in Roman numerals as (III). Therefore, the correct IUPAC name of the complex ion is **Tetrachloridoaurate (III)**. Conclusion: The correct IUPAC name of the complex ion formed when gold dissolves in aqua regia is . Thus, the correct answer is .$

49

PYQ 2024

medium

chemistry ID: mht-cet-

$What is the chemical formula of glycerol?$

1

2

3

4

Official Solution

Correct Option: $(1)$

$Glycerol (also known as glycerine) is a simple polyol compound with the chemical formula: It has: Three carbon atoms, Three hydroxyl (-OH) groups, making it highly hydrophilic and soluble in water. Structure: Applications: Used as a sweetener in food, An important ingredient in pharmaceutical formulations.$

50

PYQ 2025

medium

chemistry ID: mht-cet-

$In a reaction, . Find the product ' B ' of above reaction.$

1

$Propanoic acid$

2

$2-Methyl propanoic acid$

3

$Butanoic acid$

4

$2,2-Dimethyl ethanoic acid$

Official Solution

Correct Option: $(2)$

$Step 1: Concept Grignard reagent () reacts with dry ice () followed by hydrolysis to form carboxylic acids with one extra carbon. Step 2: Reaction Analysis - Reactant: (Isopropyl magnesium bromide). - Carbonyl Addition: Isopropyl group attaches to the Carbon of . - Hydrolysis: The intermediate salt forms . Step 3: Conclusion The structure is 2-Methylpropanoic acid (also known as Isobutyric acid). Final Answer: (B)$

51

PYQ 2025

medium

chemistry ID: mht-cet-

$Which of the following coordination compounds exhibits geometrical isomerism?$

1

2

3

4

Official Solution

Correct Option: $(2)$

$Geometrical isomerism occurs in coordination compounds with specific coordination numbers and ligand arrangements, typically in square planar (coordination number 4) or octahedral (coordination number 6) complexes. It is observed when ligands can occupy different spatial positions, such as cis (adjacent) and trans (opposite) arrangements. Let’s analyze each option: - (1) : This is an octahedral complex with six identical ligands (). Since all ligands are the same, no geometrical isomerism is possible. - (2) : This is an octahedral complex with four and two ligands, having the formula . In an octahedral complex, the two ligands can be: - Cis: Adjacent to each other (90° apart), - Trans: Opposite each other (180° apart). These distinct arrangements result in geometrical isomerism. - (3) : This is an octahedral complex with five and one ligand (). Since there is only one ligand, different spatial arrangements are not possible, so it does not exhibit geometrical isomerism. - (4) : This is a tetrahedral complex with four identical ligands. Tetrahedral complexes with four identical ligands do not show geometrical isomerism due to the symmetry of the tetrahedral geometry. Thus, the compound that exhibits geometrical isomerism is .$

52

PYQ 2025

medium

chemistry ID: mht-cet-

$IUPAC name of the chemical compound ?}$

Official Solution

Correct Option: $(1)$

$The IUPAC name of the given compound is "Bis(triphenylphosphine) dichloronickel(II)". In this compound: - The nickel (Ni) is in the +2 oxidation state, - There are two triphenylphosphine (PPh3) ligands and two chloride (Cl) ligands attached to the nickel center. In the IUPAC name: - "Bis" indicates two identical ligands (triphenylphosphine), - "Dichloro" refers to the two chloride ions, - "Nickel(II)" indicates the metal center with a +2 oxidation state.$

53

PYQ 2025

medium

chemistry ID: mht-cet-

$The solubility product of NiS is at 298 K . Calculate its solubility in moldm at the same temperature?$

1

2

3

4

Official Solution

Correct Option: $(2)$

$Step 1: Dissociation Equillibrium If solubility is, then and . Step 2: Formula Step 3: Calculation . Final Answer: (B)$

54

PYQ 2025

medium

chemistry ID: mht-cet-

$Identify the type of defect in brass alloy.$

1

$Interstitial impurity defect$

2

$Schottky defect$

3

$Substitutional impurity defect$

4

$Metal deficiency defect$

Official Solution

Correct Option: $(3)$

$Step 1: Concept Alloys like brass are formed when atoms of one metal replace atoms of another metal in the crystal lattice. Step 2: Application Brass is an alloy of Copper () and Zinc (). In its structure, Zinc atoms substitute some of the Copper atoms in the lattice positions. Step 3: Conclusion Since host atoms are replaced by impurity atoms, it is a substitutional impurity defect. Final Answer: (C)$

55

PYQ 2025

medium

chemistry ID: mht-cet-

$A compound of Xe and F is found to have atomic ratio Xe : F as 0.4 : 2.4, Find the oxidation number of Xe ?$

1

$-4$

2

$Zero$

3

$+4$

4

$+6$

Official Solution

Correct Option: $(4)$

$Step 1: Simplify Ratio Ratio . Divide both by 0.4: . Step 2: Chemical Formula The formula of the compound is . Step 3: Oxidation Number Let oxidation state of be . . Final Answer: (D)$

56

PYQ 2025

medium

chemistry ID: mht-cet-

$Which from following coordinate complexes contains the ligand 'en'?$

1

$Tetraamminecopper (II) ion$

2

$Bis(ethylenediamine) dithiocyanatoplatinum (IV)$

3

$Pentacarbonyliron (0)$

4

$Tetracyanonickelate (II)$

Official Solution

Correct Option: $(2)$

$Concept:'en' stands for ethylenediamine, a bidentate ligand: Step 1: Check ligand names. Ammine â NH Carbonyl â CO Cyano â CN Ethylenediamine â en Step 2: Identify correct complex. Only option (B) explicitly contains ethylenediamine. Step 3: Conclusion. Answer = (B)$

57

PYQ 2026

medium

chemistry ID: mht-cet-

$The EAN (Effective Atomic Number) of Iron in is:}$

1

$34$

2

$35$

3

$36$

4

$38$

Official Solution

Correct Option: $(3)$

$Step 1: Understanding the Concept: The Effective Atomic Number (EAN) rule was proposed by Sidgwick to explain the stability of coordination complexes. It represents the total number of electrons present around the central metal ion after coordination. Step 2: Key Formula or Approach: The EAN is calculated using the established formula: . Here, is the atomic number of the central metal, is its oxidation state, and is the coordination number. Step 3: Detailed Explanation: Let's analyze the given complex ion, . The central metal atom is Iron (), which has an atomic number of . Next, we calculate the oxidation state () of Iron, let's call it . The cyanide ligand () is a unidentate ligand with a charge of . The sum of the charges of the metal and ligands equals the overall charge of the complex. Thus, the oxidation state of Iron is . The coordination number () is the total number of coordinate bonds formed, which is since there are six ligands. Now, we substitute these values into the EAN formula: Step 4: Final Answer: The EAN of Iron in the given complex is 36.$

58

PYQ 2026

medium

chemistry ID: mht-cet-

$What is the Effective Atomic Number (EAN) of ?$

1

$34$

2

$36$

3

$38$

4

$40$

Official Solution

Correct Option: $(2)$

$Concept: The Effective Atomic Number (EAN) rule states that a metal atom in a coordination compound tends to achieve the electronic configuration of the nearest noble gas after accepting electrons from ligands. where is the atomic number of the metal. Step 1: Determine the atomic number of iron Iron () has atomic number: Step 2: Determine oxidation state of iron Each ligand carries a charge of . In : So iron is in the oxidation state. Step 3: Calculate electron donation from ligands Each ligand donates 2 electrons. Step 4: Apply the EAN formula Conclusion: The Effective Atomic Number of is, which corresponds to the noble gas configuration of krypton.$

59

PYQ 2026

medium

chemistry ID: mht-cet-

$The EAN of cobalt in the complex [Co(NH3)6]3+ is:$

1

$27$

2

$30$

3

$33$

4

$36$

Official Solution

Correct Option: $(4)$

$Step 1: Understanding the Question: The question asks for the Effective Atomic Number (EAN) of the central metal atom, cobalt (Co), in the coordination complex [Co(NH)] . Step 2: Key Formula or Approach: The Effective Atomic Number (EAN) can be calculated using the formula: Where: - is the atomic number of the central metal. - is the oxidation state of the central metal. - is the coordination number (number of ligands if they are monodentate). Step 3: Detailed Explanation: 1. Atomic number (): For cobalt (Co), . 2. Oxidation State (): Let the oxidation state of Co be . Ammonia (NH) is a neutral ligand, so its charge is 0. Sum of charges: . So, the oxidation state of cobalt is +3. 3. Coordination Number (): There are six NH ligands attached to the cobalt atom. Since NH is a monodentate ligand, the coordination number is 6. 4. Calculate EAN: Step 4: Final Answer: The EAN of cobalt in the complex [Co(NH)] is 36, which corresponds to the atomic number of the noble gas Krypton (Kr).$

60

PYQ 2026

medium

chemistry ID: mht-cet-

$The EAN of cobalt in the complex is:$

1

2

3

4

Official Solution

Correct Option: $(4)$

$Concept: The Effective Atomic Number (EAN) rule states that the total number of electrons around the central metal atom in a complex tends to equal the atomic number of the nearest noble gas. The formula for EAN is: where • = atomic number of the metal • Ligands donate electron pairs to the central metal atom Step 1: Find the oxidation state of cobalt. In the complex : • is a neutral ligand • Overall charge on the complex = Therefore, Step 2: Determine electrons donated by ligands. Each ligand donates 2 electrons . Number of ligands = 6 Step 3: Calculate the EAN. Atomic number of cobalt: Thus, the effective atomic number of cobalt in the complex is:$

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About Coordination Compounds - MHT-CET

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60 MCQs