Answers and Explanations for Exam 1—Multiple Choice
316 STEP 5. Build Your Test-Taking Confidence
- C—This is the only one that has a pair of elec-
trons to donate. - B—All can behave as Brønsted bases. Only B
cannot behave as an acid. - A—This is the definition of a Lewis base.
- E—The buret should be rinsed with titrant, not
water. - D—The others are normally monatomic anions.
- C—Increasing sizes indicate decreasing charge,
lower position in a column on the periodic table,
or position to the left in a period on the periodic
table. - D—The element furthest away from F.
- D—Hexammine = (NH 3 ) 6 ; chromium(III) =
Cr^3 +; chloride =Cl– - B—2 Fe(OH) 3 (s) +3 H 2 SeO 4 (aq) →Fe 2 (SeO 4 ) 3 (s)
+6 H 2 O(l) - C—The soluble compounds should be separated
and the spectator ions eliminated. - B—Magnesium nitride does form.
- D—Some of the nickel remains, the sodium does
not change, and two nitrates are formed per
nickel(II) nitrate. - A—The reactions are: NH 4
+
+OH–→NH 3 +
H 2 O and Ba^2 ++SO 42–
→BaSO 4- B—Percentages: (A) 77.8; (B) 69.6; (C) 72.0;
(D) 63.2; (E) 49.5
Approximate the atomic weights to simplify the
calculations.- E—Percentage of water: (A) 11; (B) 20; (C) 43;
(D) 50; (E) 56 - D—Nitric acid is the limiting reagent.
- A—(2.21 g)(1 mol/442 g)(3 mol O 2 /2 mol) =
7.50 × 10 -3mol. Simplify to.- B—4 C 4 H 11 N(l) +27 O 2 (g) →16 CO 2 (g) +
22 H 2 O(l) +2 N 2 (g)
19. C—Sulfuric acid is the limiting reagent.
20. A—(1.0 mol KClO 3 )(3 mol O 2 /2 mol KClO 3 ) =
1.5 mol
21. C—(0.100 mol Sr)(l mol H 2 /l mol Sr)
(22.4 L/mol) =2.24 L H 2
22. C—The average velocity is related to temperature.
23. D—Water, whenever present, will contribute its
vapor pressure.
24. B—T 2 =(V 2 T 1 )/V 1 =[(15.00 L ×400. K)/(6.00 L)]- 273 = 727 °C
- D—Small and nonpolar
- A—Definition
- B—Definition
- D—Definition
- A—^1 ⁄ 2 [2 ClF(g) +O 2 (g) →Cl 2 O(g) +OF 2 (g)]
(^1) ⁄ 2 (167.5 kJ)
(^1) ⁄ 2 [2 F 2 (g) +O 2 (g) →2 OF 2 (g)] (^1) ⁄ 2 (–43.5 kJ)
(^1) ⁄ 2 [Cl
2 O(g) +3 OF 2 (g) →2 ClF 3 (l) +2 O 2 (g)]
-^1 ⁄ 2 (394.1 kJ)
ClF(g) +F 2 (g) →C1F 3 (l) –135.1 kJ- A—Exothermic processes shift toward the start-
ing materials when heated. - A—Definition
- E—Subtract the heat of vaporization from the
original value. - D—Ni^2 +has 26 electrons. The first electrons to
leave are the 4s electrons. - D—This describes one of the 4s electrons.
- C—Diffraction is a wave phenomenon.
- A—Definition
- E—Electrons fill the orbitals individually before
pairing. Unpaired ↑ electrons =paramagnetic. - D—Definition
- B—X is F and forms a – 1 ion. Magnesium forms
a +2 ion.