1. Which one of the following is most likely to be an ionic compound?
a. CaCl2
b. CO2
c. CS2
d. SO2
2. Which one of the following is most likely to be an ionic compound?
a. ClF3
b. FeCl3
c. NH3
d. PF3
3. Which one of the following is most likely to be a covalent compound?
a. Rb2O
b. BaO
c. SrO
d. SeO2
4. Which one of the following is most likely to be a covalent compound?
a. KF
b. CaCl2
c. SF4
d. Al2O3
5. The Lewis dot symbol for the lead atom is:
6. The Lewis dot symbol for the S 2- ion is:
7. Which one of the following ionic solids would have the largest lattice energy?
a. NaCl
b. NaF
c. CaBr2
d. CaCl2
8. Which of the following ionic solids would have the largest lattice energy?
a. SrO
b. NaF
c. CaBr2
d. CsI
9. Which of the following solids would have the highest melting point?
a. NaF
b. NaCl
c. NaBr
d. NaI
10. Which of the following solids would have the lowest melting point?
a. KI
b. KBr
c. KCl
d. KF
11. Which of the elements listed below has the greatest electronegativity?
a. Na
b. As
c. Ga
d. Cs
12. Which of the elements listed below is the least electronegative?
a. Sr
b. V
c. Ni
d. P
13. Which of the bonds below would have the greatest polarity (i.e., highest percent ionic character)?
a. Si ¾ P
b. Si ¾ S
c. Si ¾ Se
d. Si ¾ Cl
14. The Lewis structure for CS2 is:
15. Assuming the octet rule is obeyed, how many covalent bonds will a nitrogen atom form to give a formal charge of zero?
a. 0
b. 1
c. 2
d. 3
16. Which of the following is a useful guideline for the application of formal charges in neutral molecules?
a. A Lewis structure in which there are no formal charges is preferred.
b. Lewis structures with large formal charges (e.g., +2,+3 and/or -2,-3) are preferred.
c. The preferred Lewis structure is one in which positive formal charges are on the most electronegative atoms.
17. For which of these species does the best Lewis structure have two or more equivalent resonance structures?
a. HCO2-
b. SCN-
c. CNO-
d. N3-
18. Which one of the following compounds does not follow the octet rule?
a. NF3
b. CF4
c. PF5
d. AsH3
19. Which one of the following compounds does not follow the octet rule?
a. NF3
b. CO2
c. CF4
d. NO
20. Use the bond enthalpy data given to estimate the heat released when 6.50g of nitrogen gas reacts with excess hydrogen gas to form ammonia at 25°C. BE(N?N) = 941.4 kJ/mol, BE(H-H) = 436.4 kJ/mol, BE(N-H) = 393 kJ/mol
a. 228 kJ
b. 340 kJ
c. 107 kJ
d. 24.9 kJ
21. Give the number of lone pairs around the central atom and the molecular geometry of CBr4.
a. 0 lone pairs, square planar
b. 0 lone pairs, tetrahedral
c. 1 lone pair, square pyramidal
d. 1 lone pair, trigonal bipyramidal
22. Give the number of lone pairs around the central atom and the molecular geometry of SCl2.
a. 0 lone pairs, linear
b. 1 lone pair, bent
c. 2 lone pairs, bent
d. 3 lone pairs, bent
23. According to the VSEPR theory, the geometry of the SO3 molecule is:
a. pyramidal.
b. tetrahedral.
c. trigonal planar.
d. distorted tetrahedron (seesaw).
24. According to the VSEPR theory, the molecular geometry of ammonia is:
a. linear.
b. trigonal planar.
c. bent.
d. trigonal pyramidal.
25. The bond angle in SCl2 is expected to be:
a. a little less than 109.5°.
b. 109.5°.
c. a little more than 109.5°.
d. 120°.
26. The bond angle in Cl2O is expected to be approximately:
a. 90°.
b. 109.5°.
c. 120°.
d. 145°.
27. Complete the following sentence: The PCl5 molecule has:
a. nonpolar bonds, and is a nonpolar molecule.
b. nonpolar bonds, but is a polar molecule.
c. polar bonds, and is a polar molecule.
d. polar bonds, but is a nonpolar molecule.
28. Which one of the following molecules has a non-zero dipole moment?
a. BeCl2
b. Br2
c. BF3
d. IBr
29. Which one of the following molecules has a zero dipole moment?
a. CO
b. CH2Cl2
c. SO3
d. SO2
30. Indicate the type of hybrid orbitals used by the central atom in CCl4.
a. sp
b. sp2
c. sp3
d. sp3d
31. Indicate the type of hybrid orbitals used by the central atom in SF6.
a. sp
b. sp2
c. sp3
d. sp3d2
32. What is the hybridization on the central atom in NO3- ?
a. sp
b. sp2
c. sp3
d. sp3d
33. Which of the following is not true of molecular orbitals?
a. The number of molecular orbitals formed is always equal to the number of atomic orbitals combined.
b. A molecular orbital can accommodate up to two electrons.
c. When electrons are added to orbitals of the same energy, the most stable arrangement is predicted by Hund's rule.
d. For any substance, the number of electrons in molecular orbitals is equal to the sum of all the valence electrons on the bonding atoms.
34. Which of the following correctly lists species in order of increasing bond length?
a. O2 < O2+ < O2-
b. O2- < O2 < O2+
c. O2+ < O2 < O2-
d. O2- < O2+ < O2
35. The N - N - H bond angles in hydrazine N2H4 are 112°. What is the hybridization of the nitrogen orbitals predicted by valence bond theory?
a. sp3
b. sp2
c. sp4
d. sp6