Competitive Exams: Chemistry MCQs (Practice-Test 19 of 31)

  1. What are the geometric shape and the oxidation number of the copper atom, respectively, for the complex ion, [Cu (NH3) 4 (OH2) 2]2 +?

    1. tetrahedral; + 2

    2. square planar; 2

    3. octahedral; + 2

    4. linear; + 3

    5. trigonal planar; + 1

  2. Consider the experimental data below for compounds 1 and 2 which have the same molecular formula, C2H6O, compoundboiling point, oCfreezing point, oC 178.5 − 117.3 & 2 − 25.0 − 138.5

  3. Which of the following statements is TRUE?

    1. Compounds 1 and 2 are not isomers.

    2. Compounds 1 and 2 are optical isomers.

    3. Compounds 1 and 2 have identical physical properties.

    4. All of the above are TRUE.

    5. None of these is TRUE.

  4. What are the oxidation number (ON) and coordination number (CN) in the coordination compound, [Cu (en) (NH3) 2]Cl2 (Be careful.)?

    1. ON = 1, CN = 1

    2. ON = 1, CN = 2

    3. ON = 2, CN = 2

    4. ON = 2, CN = 3

    5. ON = 2, CN = 4

  5. Which one of the following is the correct electron configuration for the Fe3 + ion?

    1. [Ar] 4s1 3d5

    2. [Ar] 4s2 3d3

    3. [Ar] 4s1 3d4

    4. [Ar] 3d6

    5. [Ar] 3d5

  6. Which one of the following best explains why water is a monodentate ligand?

    1. The oxygen atom in a water molecule only has one lone pair of electrons that it can use to form a coordinate covalent bond to a metal atom.

    2. Each hydrogen atom in a water molecule has only one electron with which to form a coordinate covalent bond to a metal atom.

    3. The oxygen atom in a water molecule has two lone pairs of electrons, but both pairs are used to form a single coordinate covalent bond to a metal atom.

    4. The oxygen atom in a water molecule has two lone pairs of electrons, but the second lone pair is not close enough to a second coordination site to form a coordinate covalent bond.

    5. None of these.

  7. What are the coordination number and the oxidation state, respectively, of the cobalt atom in the compound [Co (NH3) 5Cl]Cl2?

    1. 4; + 2

    2. 4; + 3

    3. 5; + 2

    4. 6; + 2

    5. 6; + 3

  8. “Cobalt Yellow” is a pigment used in oil paints, and contains the coordination compound K3[Co (NO2) 6]. How many unpaired electrons are there on the cobalt atom in this compound? Note that NO2-is a strong-field ligand.

    1. 0

    2. 1

    3. 2

    4. 3

    5. 4

  9. When a concentrated solution of NH3 is added to a solution containing Zn (NO3) 2, a colorless solution containing the complex ion Zn (NH3) 42 + results. Which one of the following best explains why this solution is colorless?

    1. The Zn atom does not have any 3d electrons; thus, an electron cannot be transferred between the split 3d orbitals.

    2. The Zn atom does not have any 4s electrons; thus, an electron cannot be transferred between the split 4s orbitals.

    3. The 3d orbitals on the Zn atom are completely filled; thus, an electron cannot be transferred between the split 3d orbitals.

    4. The Zn atom does not have any unpaired electrons which are necessary in order to transfer an electron between the split 3d orbitals.

    5. The Zn (NH3) 42 + ion only absorbs blue light which makes the solution colorless.

  10. When solid CoCl2 is dissolved in water, a pink solution results and the following equilibrium is established: Co (H2O) 62 + (aq) + 4 Cl- (aq) ⇔ CoCl42- (aq) + 6 H2O (l)

    1. In aqueous solution, the Co (H2O) 62 + ion is pink, and the CoCl42-ion is blue.

    2. The shape of Co (H2O) 62 + is octahedral whereas the shape of CoCl42-is tetrahedral.

    Which one of the following best describes what will happen when a concentrated solution of HCl is added to the CoCl2 solution without changing the volume significantly?

    1. Because a solution of HCl is colorless, the color of the CoCl2 solution will not change.

    2. Because HCl is a strong acid, the number of unpaired electrons in Co (H2O) 62 +, but not CoCl42-, will change.

    3. The concentration of Co (H2O) 62 + will decrease and the concentration of CoCl42-will increase; the color of the solution will become more blue.

    4. The concentration of Co (H2O) 62 + will increase and the concentration of CoCl42-will decrease; the color of the solution will become more pink.

    5. The addition of HCl will have no effect on the position of the equilibrium.

  11. Which one of the following can form geometric isomers?

    1. [AgCl2]-

    2. [Cu (NH3) 4]2 + (square planar)

    3. [Co (OH2) 5Cl]2 +

    4. Ni (OH2) 2Br2 (square planar)

    5. None of these can form geometric isomers.

  12. Which of the following types of isomers can [Ag (NH3) 2] + form?

    1. Linkage Isomers

    2. Geometric Isomers

    3. Optical Isomers

      1. 1 only

      2. 1 and 2

      3. 1 and 3

      4. 3 only

      5. None of these.

  13. What color would we expect an aqueous solution containing Ti (OH2) 44 + to be?

    1. blue

    2. red

    3. green

    4. yellow

    5. colorless

  14. What is the oxidation number of platinum in the coordination compound, Pt (NH3) 2Cl2?

    1. -2

    2. -1

    3. 0

    4. + 1

    5. + 2

  15. For the coordination compound, Na2[Cd (en) (CN) 4], what are the coordination number (CN) and oxidation number (O. N.) of the central metal ion (Note: The letters, en, represent the ligand, ethylenediamine.).

    1. CN = 6, ON = + 2.

    2. CN = 5, ON = + 2.

    3. CN = 4, ON = + 3.

    4. CN = 4, ON = + 2.

    5. CN = 3, ON = + 1.