Coordination Compounds MCQ Quiz - Objective Question with Answer for Coordination Compounds - Download Free PDF

The correct answer is CaO.

Key Points

• Calcium oxide, commonly known as quicklime or burnt lime, is a chemical compound with the formula CaO.
• It is a white, caustic, alkaline, crystalline solid at room temperature.
• Calcium oxide is produced by thermal decomposition of calcium carbonate (CaCO₃) in a lime kiln.
• It is used in various industries, including steel manufacturing, environmental applications for pH control, and in the production of cement.
• In water treatment, CaO is used to soften water by removing temporary hardness.
• It reacts vigorously with water to form calcium hydroxide (Ca(OH)₂), also known as slaked lime.

 Additional Information

• Ca2O
  • This formula suggests the combination of two calcium atoms with one oxygen atom, which is incorrect because calcium typically forms a +2 oxidation state and bonds with one oxygen atom.
• CaO2
  • This formula suggests the presence of one calcium atom and two oxygen atoms, indicating calcium peroxide rather than calcium oxide.
  • Calcium peroxide (CaO₂) is used as an oxidizing agent and for oxygen generation in aquaculture.
• Ca2O3
  • This formula does not correspond to any known stable compound in chemistry. It suggests a non-existent stoichiometric relationship between calcium and oxygen.

The correct answer is Alfred Werner.

Key Points

• In 1893, the Swiss chemist, Alfred Werner, was the first to understand the molecular structures of inorganic substances – chemical compounds that do not contain carbon.
• Werner asserts that the attraction forces come uniformly from the centre of the atom rather than being associated with any particular directions in the atom. He clarified the structures of substances by assigning a new coordination number to an atom's bonds.
• The octahedral structure of transition metal complexes was proposed by Alfred Werner, who was awarded the Nobel Prize in Chemistry in 1913.
• Modern coordination chemistry's foundation was created by Werner and he was the first to receive the Nobel prize for inorganic chemistry.

Additional Information

• William Ramsay, who won the 1904 Nobel Prize in Chemistry, contributed to the creation of the noble gases as a new group in the periodic table.
• In 1943, George de Hevesy, a radiochemist from Hungary, won the Nobel Prize in Chemistry for discovering the radiotracer concept.
• John Dalton was an English chemist, physicist, and meteorologist best known for his work on human optics and for introducing the atomic theory to chemistry.

The correct answer is Alfred Werner.

Key Points

• In 1893, the Swiss chemist, Alfred Werner, was the first to understand the molecular structures of inorganic substances – chemical compounds that do not contain carbon.
• Werner asserts that the attraction forces come uniformly from the centre of the atom rather than being associated with any particular directions in the atom. He clarified the structures of substances by assigning a new coordination number to an atom's bonds.
• The octahedral structure of transition metal complexes was proposed by Alfred Werner, who was awarded the Nobel Prize in Chemistry in 1913.
• Modern coordination chemistry's foundation was created by Werner and he was the first to receive the Nobel prize for inorganic chemistry.

Additional Information

• William Ramsay, who won the 1904 Nobel Prize in Chemistry, contributed to the creation of the noble gases as a new group in the periodic table.
• In 1943, George de Hevesy, a radiochemist from Hungary, won the Nobel Prize in Chemistry for discovering the radiotracer concept.
• John Dalton was an English chemist, physicist, and meteorologist best known for his work on human optics and for introducing the atomic theory to chemistry.

The correct answer is Alfred Werner.

Key Points

• In 1893, the Swiss chemist, Alfred Werner, was the first to understand the molecular structures of inorganic substances – chemical compounds that do not contain carbon.
• Werner asserts that the attraction forces come uniformly from the centre of the atom rather than being associated with any particular directions in the atom. He clarified the structures of substances by assigning a new coordination number to an atom's bonds.
• The octahedral structure of transition metal complexes was proposed by Alfred Werner, who was awarded the Nobel Prize in Chemistry in 1913.
• Modern coordination chemistry's foundation was created by Werner and he was the first to receive the Nobel prize for inorganic chemistry.

Additional Information

• William Ramsay, who won the 1904 Nobel Prize in Chemistry, contributed to the creation of the noble gases as a new group in the periodic table.
• In 1943, George de Hevesy, a radiochemist from Hungary, won the Nobel Prize in Chemistry for discovering the radiotracer concept.
• John Dalton was an English chemist, physicist, and meteorologist best known for his work on human optics and for introducing the atomic theory to chemistry.

The correct answer is CaO.

Key Points

• Calcium oxide, commonly known as quicklime or burnt lime, is a chemical compound with the formula CaO.
• It is a white, caustic, alkaline, crystalline solid at room temperature.
• Calcium oxide is produced by thermal decomposition of calcium carbonate (CaCO₃) in a lime kiln.
• It is used in various industries, including steel manufacturing, environmental applications for pH control, and in the production of cement.
• In water treatment, CaO is used to soften water by removing temporary hardness.
• It reacts vigorously with water to form calcium hydroxide (Ca(OH)₂), also known as slaked lime.

 Additional Information

• Ca2O
  • This formula suggests the combination of two calcium atoms with one oxygen atom, which is incorrect because calcium typically forms a +2 oxidation state and bonds with one oxygen atom.
• CaO2
  • This formula suggests the presence of one calcium atom and two oxygen atoms, indicating calcium peroxide rather than calcium oxide.
  • Calcium peroxide (CaO₂) is used as an oxidizing agent and for oxygen generation in aquaculture.
• Ca2O3
  • This formula does not correspond to any known stable compound in chemistry. It suggests a non-existent stoichiometric relationship between calcium and oxygen.

CONCEPT:

• The standard electrode potential (M³⁺/M²⁺) indicates the tendency of a metal ion to be reduced from +3 to +2 oxidation state.
• Among Mn, Cr, Co, and Fe, cobalt (Co) has the highest standard electrode potential for the M³⁺/M²⁺ couple.
• The complex [M(CN)₆]⁴⁻ is a coordination complex with a strong field ligand (CN⁻), causing large crystal field splitting and usually leading to low-spin configurations.
• In an octahedral field, the d-orbitals split into t₂g (lower energy) and e_g (higher energy) orbitals.
• For low-spin d⁷ configuration of Co(II) in [Co(CN)₆]⁴⁻, electrons fill t₂g orbitals first, with the remaining electron occupying one e_g orbital.

EXPLANATION:

Co has highest standard electrode potential (M+3/M+2) among Mn, Cr, Co, Fe

 Complex is [Co(CN)6 ]4– and its splitting is as follows. 

•  electron in eg orbital is one.

• Complex: [Co(CN)₆]⁴⁻ with strong field CN⁻ ligands causes low-spin configuration.
• Electronic configuration: Co(II) is d⁷; in low-spin octahedral complex, t₂g orbitals are fully filled (6 electrons) and one electron occupies e_g orbital.
• Number of electrons in e_g orbital: 1

Therefore, the number of electrons present in the e_g orbital of the complex is 1.

CONCEPT:

Oxidation Number

• The oxidation number (or oxidation state) of an atom in a molecule or ion is the hypothetical charge that atom would have if all bonds to atoms of different elements were 100% ionic.
• Rules for assigning oxidation numbers:
  • Oxidation number of a free element is 0.
  • Oxidation number of a monoatomic ion is equal to its charge.
  • Group 1 elements in compounds have an oxidation number of +1, and Group 2 elements have +2.
  • In compounds, hydrogen is assigned +1, and oxygen is assigned -2 (except in peroxides and superoxides).
  • The sum of the oxidation numbers in a neutral compound is 0, and in a polyatomic ion, it equals the charge of the ion.

EXPLANATION:

• In the given compound K₄[Fe(CN)₆]:
  • The compound is electrically neutral, so the sum of oxidation numbers of all atoms is 0.
  • Potassium (K) is in Group 1, so its oxidation number is +1. Since there are 4 potassium atoms, the total contribution from potassium is 4 × (+1) = +4.
  • The cyanide ion (CN^-) has a charge of -1. Since there are 6 cyanide ions, the total contribution from cyanide is 6 × (-1) = -6.
• Let the oxidation number of Fe be x. 

  4 × (+1) + x + 6 × (-1) = 0

  +4 + x - 6 = 0

  x = +2

Therefore, the oxidation number of Fe in K₄[Fe(CN)₆] is +2.

Electronic configuration of ions and their oxidation no.

\(MnO_4^- = +7; \, [Ar]^{18} 3d^5 4s^2 = 7\).

\(CrO_7^{2-} = +6; \, [Ar]^{18} 3d^5 4 s^1 = 6\).

\(VO_4^{3-} = +5; \, [Ar]^{18}3d^3 4s^2 = 5\).

\(FeO_4^{2-} = +6; \, [Ar]^{18} 3d^64s^2 = 8\).

So, Fe compound is the right answer.