1101 Final Exam_01/19/22_(C)
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) A sample of gas (1.9 mol) is in a flask at 21 °C and 697 mm Hg. The flask is opened and more gas is added to the flask. The new pressure is 841 mm Hg and the temperature is now 26 °C. There are now ________ mol of gas in the flask.
A) 2.9 B) 0.28 C) 2.3 D) 1.6 E) 3.5
Answer: C
2) The density of HCN is ________ g/L at STP.
A) 0.829 B) 2.21 C) 1.21 D) 329 E) 605
Answer: C
3)Zinc reacts with aqueous sulfuric acid to form hydrogen gas:
Zn (s) + H2SO4 (aq) ZnSO4 (aq) + H2 (g)
In an experiment, 201 mL of wet H2 is collected over water at 27 °C and a barometric pressure of 765 torr. How many grams of Zn have been consumed? The vapor pressure of water at 27 °C is 26.74 torr.
A) 4.38 × 106 B) 394 C) 519 D) 3.94 × 105 E) 0.519
Answer: E
4)Using the van der Waals equation, the pressure in a 22.4 L vessel containing 1.50 mol of chlorine gas at 0.00 °C is ________ atm. (a = 6.49 L2-atm/mol2, b = 0.0562 L/mol)
A) 1.91 B) 0.993 C) 0.676 D) 1.50 E) 1.48
Answer: E
5) A 255 mL round-bottom flask is weighed and found to have a mass of 114.85 g. A few milliliters of an easily vaporized liquid are added to the flask and the flask is immersed in a boiling water bath. All of the liquid vaporizes at the boiling temperature of water, filling the flask with vapor. When all of the liquid has vaporized, the flask is removed from the bath, cooled, dried, and reweighed. The new mass of the flask and the condensed vapor is 115.23 g. Which of the following compounds could the liquid be? (Assume the ambient pressure is 1 atm.)
A)C3H7OH B)C4H9OH C)C4H10 D)C2H6 E)C2H5OH
Answer: E
6) How much faster does 235UF6 effuse than 238UF6?
A) 1.013 times as fast B) 1.009 times as fast C) 1.004 times as fast D) 1.018 times as fast E) 1.006 times as fast Answer: E
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7) According to kinetic-molecular theory, in which of the following gases will the root-mean-square speed of the molecules be the highest at 200 °C?
A)N2O B)O2 C)UF6 D)NH3
E) None. The molecules of all gases have the same root-mean-square speed at any given temperature.
Answer: D
8)The electron-domain geometry and the molecular geometry of a molecule of the general formula ABn will always be the same if ________.
A) n is less than four B) the octet rule is obeyed
C) there is more than one central atom D) there are no lone pairs on the central atom
E) n is greater than four Answer: D
9)For molecules of the general formula ABn, n can be greater than four ________.
A) only when A is boron or beryllium B) only when A is carbon
C) only when A is an element from the third period or below the third period D) for any element A
E) only when A is Xe Answer: C
10)Three monosulfur fluorides are observed: SF2, SF4, and SF6. Of these, ________ is/are polar.
A)SF6 only B)SF2 only
C)SF2, SF4, and SF6 D)SF2 and SF4 only
E)SF4 only Answer: D
11)There are ________ bonds and ________ bonds in H3C-CH2-CH CH-CH2-C CH.
A) 12, 2 B) 16, 3 C) 14, 2 D) 13, 2 E) 10, 3
Answer: B
12) Of the following, the central atom is sp3d2 hybridized only in ________.
A)XeF4 B)BeF2 C) Br3- D)PH3 E)PCl5
Answer: A
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13)Which of the following molecules or ions will exhibit delocalized bonding?
SO2 SO3 SO32-
A) SO32- only B)SO2 and SO3
C) SO2, SO3, and SO32- D) SO3 and SO32-
E) None of the above will exhibit delocalized bonding.
Answer: B
14) Of the following, ________ appear(s) to gain mass in a magnetic field.
B2 N2 O2
A)N2 and O2 B)B2 and O2 C)N2 only D)B2 and N2 E)O2 only
Answer: B
15)The order of MO energies in B2, C2, and N2 ( 2p > 2p), is different from the order in O2, F2, and Ne2 ( 2p < 2p). This is due to ________.
A)less effective overlap of p orbitals in B2, C2, and N2 B)greater 2s-2p interaction in O2, F2, and Ne2 C)greater 2s-2p interaction in B2, C2, and N2
D) the more metallic character of boron, carbon and nitrogen as compared to oxygen, fluorine, and neon E)less effective overlap of p orbitals in O2, F2, and Ne2
Answer: C
16) Which will have a larger band gap: GaN, GaP, GaAs, or GaSb?
A) GaP B) GaAs C) GaN D) GaSb
E) All choices have identical band gaps.
Answer: C
17) Potassium metal crystallizes in a body-centered cubic structure with a unit cell edge length of 5.31 Å. The radius of a potassium atom is ________ Å.
A) 1.33 B) 2.30 C) 5.31 D) 1.88 E) 2.66
Answer: B
18) A solid has a very high melting point, great hardness, and poor electrical conduction. This is a(n) ________
solid.
A) covalent network B) ionic
C) metallic and covalent network D) molecular
E) metallic Answer: A
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19) For a substitutional alloy to form, the two metals combined must have similar A) atomic radii and chemical bonding properties.
B) band gap and reactivity.
C) number of valance electrons and electronegativity.
D) ionization potential and electron affinity.
E) reduction potential and size.
Answer: A
20) Covalent bonding occurs in both molecular and covalent-network solids. Which of the following statements best explains why these two kinds of solids differ so greatly in their hardness and melting points?
A) The molecules in molecular solids have stronger covalent bonding than covalent-network solids do.
B) The molecules in molecular solids are held together by weak intermolecular interactions.
C) The atoms in covalent-network solids are more polarizable than those in molecular solids.
D) Molecular solids are denser than covalent-network solids.
Answer: B
E) All of the above are wrong.
21) Which one of the following exhibits dipole-dipole attraction between molecules?
A)SiO2 B)Cl2 C)CBr4 D)AsH3 E)BH3
Answer: D
22) Of the following substances, ________ has the highest boiling point.
A)CH3CH2OH B)Cl2
C)HOCH2CH2CH2OH D)C4H10
E)N2 Answer: C
23) Which type of liquid crystal is colored and changes color with temperature?
A) smectic B B) nematic C) cholesteric D) smectic C E) smectic A
Answer: C
24) The enthalpy change for converting 10.0 g of ice at -50.0 °C to water at 50.0 °C is ________ kJ. The specific heats of ice, water, and steam are 2.09 J/g-K, 4.18 J/g-K, and 1.84 J/g-K, respectively. For H2O, Hfus = 6.01 kJ/mol, and Hvap = 40.67 kJ/mol.
A) 4.38 B) 3138 C) 9.15 D) 6.47 E) 12.28
Answer: D
25) Of the following, ________ is the most volatile.
A)C2H6 B)C2Cl6 C)C2Br6 D)C2I6 E)C2F6
Answer: A
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