Competitive Exams: Chemistry MCQs (Practice-Test 21 of 31)

  1. Given that nickel metal can be written as [Ar] 4s2 3d8, which is the correct representation for the Ni2 + ion.

    1. [Ar] 4s0 3d8

    2. [Ar] 4s2 3d6

    3. [Ar] 4s1 3d7

    4. [Ar] 4s0 3d5

    5. correct response not given

  2. Use the following information to answer questions 27, 28 and 29 related to the crystal-field theory of coordination compounds. Ferric ion (Fe3 + ) forms the complexes FeF63-and Fe (CN) 63-with fluoride (F-) and cyanide (CN-) ions. Also, F-is a weaker-field ion than is CN-in the spectrochemical series, i.e.. F-< ____ < CN-. We would expect FeF63-to:

    1. have a larger crystal field splitting energy than Fe (CN) 63-.

    2. have a smaller magnetic moment than Fe (CN) 63-.

    3. absorb light at a longer wavelength (lower energy) than Fe (CN) 63-.

    4. be more soluble than Fe (CN) 63-.

  3. Use the following information to answer questions 27, 28 and 29 related to the crystal-field theory of coordination compounds. Ferric ion (Fe3 + ) forms the complexes FeF63-and Fe (CN) 63-with fluoride (F-) and cyanide (CN-) ions. Also, F-is a weaker-field ion than is CN-in the spectrochemical series, i.e.. F-< ____ < CN-. We would expect Fe (CN) 63-to:

    1. have a smaller crystal-field splitting energy than FeF63-.

    2. have a smaller magnetic moment than FeF63-.

    3. absorb light at a longer wavelength (lower energy) than FeF63-.

    4. be more soluble than FeF63-.

  4. Use the following information to answer questions 27, 28 and 29 related to the crystal-field theory of coordination compounds. Ferric ion (Fe3 + ) forms the complexes FeF63-and Fe (CN) 63-with fluoride (F-) and cyanide (CN-) ions. Also, F-is a weaker-field ion than is CN-in the spectrochemical series, i.e.. F-< ____ < CN-. We would expect both FeF63-and Fe (CN) 63-to form:

    1. linear structures.

    2. tetrahedral structures.

    3. square planar structures.

    4. octahedral structures.

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  5. What is the oxidation state of chromium, AND the coordination number, for the coordination compound, [Cr (en) 2 (OH) 2]Cl?

    1. + 2, 4

    2. + 3, 4

    3. + 3, 5

    4. + 3, 6

    5. + 5, 6

  6. All coordination compounds which contain a Zn2 + transition metal ion are colorless. Which of the following statements best explains this observation?

    1. Zn2 + contains unpaired electrons so it should be colorless.

    2. All of the 3d orbitals in Zn2 + are filled; therefore, the transfer of an electron cannot occur.

    3. Compounds containing Zn2 + absorb only blue light so they appear colorless.

    4. Compounds containing Zn2 + absorb only red light so they appear colorless.

    5. There is insufficient information to explain this observation.

  7. Coordination compounds which contain cyanide, CN-, ligands tend to be yellow whereas coordination compounds which contain water, H2O, ligands tend to be blue or green because:

    1. the complexes diffract light at different angles.

    2. cyanide is a weak-field ligand and water is a strong-field ligand.

    3. cyanide is a strong-field ligand and water is a weak-field ligand.

    4. cyanide compounds absorb yellow light and water compounds absorb blue or green light.

    5. The basic premise of the question is incorrect because both water and cyanide are colorless and accordingly cannot influence the color of the coordination compounds.

  8. In the Qualitative Analysis scheme, the confirmatory test for the Co2 + ion was the formation of the blue Co (SCN) 42-complex ion. Assume that the SCN-ligand is a strong-field ligand and that this species is tetrahedral, and determine the number of unpaired electrons in this complex ion.

    1. 1

    2. 2

    3. 3

    4. 4

    5. 5

  9. In the crystal field model for an octahedral complex, the dz2 and dx2 − y2 orbitals (eg set) are at higher energy than the dxy, dxz and dyz orbitals (t2g set). Which one of the following statements best explains this behavior?

    1. The eg orbitals experience less electrostatic repulsion with the negative point charges than the t2g orbitals.

    2. The eg orbitals experience more electrostatic repulsion with the negative point charges than the t2g orbitals.

    3. The t2g orbitals point directly at the negative point charges.

    4. The splitting of the two sets of orbitals is also present in the free ion and therefore the negative point charges have no effect.

    5. The eg orbitals are at higher energy because there are only two of them.

  10. What is the oxidation state of the metal ion in the complex Ni (NH3) 6Cl2?

    1. -1

    2. 0

    3. + 1

    4. + 2

    5. + 3

  11. How many total isomers (structural isomers and stereoisomers) exist for the complex ion [Co (NH3) 5Cl]2 +?

    1. 1

    2. 2

    3. 3

    4. 4

    5. 6

  12. Which of the following compounds would be paramagnetic?

    1. Sc (NH3) 63 + (high spin)

    2. Zn (OH) 42- (tetrahedral)

    3. Co (NH3) 63 + (high spin)

    4. Fe (CN) 64- (low spin)

  13. Why are many coordination compounds colored?

    1. The equilibrium established between the coordination compounds and air lies on the product side.

    2. The energy required to excite an electron to an excited state is often the same as the energy of light in the visible region.

    3. The Crayola Corporation likes it that way.

    4. They all absorb water vapor, which normally hides all of the colors