100 Practice Questions Midterm 1 Chem1C PDF

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100 Practice Questions for Chem 1C Midterm 1 - Joseph 1.

Which of the following statements is incorrect? A) Ionic bonding results from the transfer of electrons from one atom to another. B) Dipole moments result from the unequal distribution of electrons in a molecule. C) The electrons in a polar bond are found nearer to the more electronegative element. D) A molecule with very polar bonds can be nonpolar. E) Linear molecules cannot have a net dipole moment.

2.

Which of the following shows these molecules in order from most polar to least polar? A) CH4 > CF2Cl2 > CF2H2 > CCl4 > CCl2H2 B) CH4 > CF2H2 > CF2Cl2 > CCl4 > CCl2H2 C) CF2Cl2 > CF 2H2 > CCl2H2 > CH4 = CCl4 D) CF2H2 > CCl2H2 > CF2Cl2 > CH4 = CCl4 E) CF2Cl2 > CF2H2 > CCl4 > CCl2H2 > CH4

3.

Which of the following is polar? A) SiF4 B) XeF2 C) BCl3 D) NBr3 E) SBr6

4.

Which statement is correct? A) H2O is linear. B) The molecule ClO2 cannot be accurately described by a Lewis structure consistent with the octet rule. C) The diatomic molecule Cl2 is an example of a polar molecule. D) The bonds in LiF have a more covalent character than those in F 2. E) none of these

Use the following to answer question 5: Consider the following molecules. I. BF 3 II. CHBr 3 (C is the central atom.) III. Br 2 IV. XeCl2 V. CO VI. SF 4 Select the molecule(s) that fit the given statement. 5. A) B) C) D) E) 6.

These molecules have a zero net dipole moment. III, V I, III, IV III, IV, V I, III, IV, VI none of them

Select the best Lewis structure for acetone, CH3COCH3. H H

H

A) H

B)

H

C C O C H H

H

O

H

C

C

C H

H

H

H

C)

H C C O H C H H H

H H H C C O C H H H H H

D)

H

H C C C O H H

E) 7.

The Lewis structure for H3BO3 is A) H O B O H

O H B)

H

O

B

O

H

O

H

O H C)

H

O

B O H

D) H O

B

O

H

O

H

O H E)

H

O

B O H

8.

Which of the following is not a valid resonance structure for N3–?

N

N

N

N

N

N

N

N

N

N

N

N

-

A)

-

B)

-

C)

D) E)

All are valid.

Use the following to answer question 9: Draw the Lewis structures of the molecules below, and use them to answer the following questions. I. BH3 II. NO2 III. SF 6 IV. O3 V. PCl5 9.

Which of these molecules show resonance? A) I, II B) II, IV C) II, V D) III, IV E) III, V

10.

Which of the following has an incomplete octet in its Lewis structure? A) SO2 B) ICl C) SF2 D) F2 E) NO

11.

The molecule XCl5– has a square pyramidal shape. Which of the following atoms could be X? A) O B) P C) Xe D) S E) At least two of these atoms could be X.

12.

The Cl–Kr–Cl bond angle in KrCl4 is closest to A) 90°. B) 109°. C) 120°. D) 150°. E) 360°

13.

Of the following, which molecule has the largest bond angle? A) SO3 B) SF2 C) HCN D) H2S E) PF 3

14.

Select the correct molecular structure for SF 4. A) linear B) bent C) pyramidal D) tetrahedral E) none of these

15.

Select the correct molecular structure for I3–. A) linear B) bent C) pyramidal D) tetrahedral E) none of these E) none of these

16.

How many of the following molecules and ions are linear? NCl3 NH4+ SCNCO2 NO2A) B) C) D) E)

0 1 2 3 4

17.

What type of structure does the XeOF 2 molecule have? A) pyramidal B) tetrahedral C) T-shaped D) trigonal planar E) octahedral

18.

Which ion is planar? A) PF 4+ B) CO32– C) SO32– D) ClO4– E) SCl5-

19.

Select the correct molecular structure for PO33–. A) pyramidal B) tetrahedral C) square planar D) octahedral E) none of these

20.

Which of the following molecules contains a nitrogen atom that is sp 2 hybridized? A) NH3 B) NO3C) N2 D) HCN E) C2N2

21.

Consider the structure of glycine, the simplest amino acid:

H2N

H

O

C

C

OH

H What is the total number of  bonds in the molecule? A) B) C) D) E) 22.

0 1/2 1 2 More information is needed.

What is the hybridization of I in the molecule ICl3? A) sp B) sp2 C) sp3 D) dsp3 E) d2sp3

23.

What is the hybridization of S in the molecule H2S? A) sp B) sp2 C) sp3 D) dsp3 E) d2sp3

24.

What is the hybridization of C in the ion CN-? A) sp B) sp2 C) sp3 D) dsp3 E) d2sp3

25.

Atoms that are sp3 hybridized form ____ pi bond(s). A) 0 B) 1 C) 2 D) 3 E) 4

26.

What is the hybridization of the central atom in SF6? A) sp B) sp2 C) sp3 D) dsp3 E) d2sp3

27.

What is the hybridization of the central atom in IF5? A) sp B) sp2 C) sp3 D) dsp3 E) d2sp3

28.

What is the hybridization of the central atom in SF4? A) sp B) sp2 C) sp3 D) dsp3 E) d2sp3

29.

Consider the following molecule. (Lone pairs are not drawn in.)

O H2C CH C CH2 1

2

3

4

C

N

5

Specify the hybridization of each carbon atom (in numeric order: C-1 C-2 A) B) C) D) E)

2

sp sp2 sp2 sp2 sp

2

2

3

sp sp sp sp2 sp2 sp3 2 3 sp sp sp3 ssp2 sp3 sp3 sp sp sp 2

sp sp3 sp sp3 sp

C-3 C-4 C-5).

Use the following to answer questions 30-3 1: Consider the following molecule. (Lone pairs are not drawn in.)

H

H

O

Cl

C

C

C

H

C

N

H

30.

What is the hybridization of the carbon atom that is double-bonded to oxygen? A) sp B) sp2 C) sp3 D) dsp3 E) d2sp3

31.

What is the hybridization of the carbon atom that is bonded to chlorine? A) sp B) sp2 C) sp3 D) dsp3 E) d2sp3

32.

Which of the following has two  bonds? A) C2H6 B) C2H4 C) C2H2 D) at least two of these E) none of these

33.

Consider the following Lewis structure. (Lone pairs are not drawn in.)

H

O

H

H

H C

C

C

C

3

2

1

H

H Which statement about the molecule is false? A) B) C) D) E)

There are 10 sigma and 2 pi bonds. C-2 is sp2 hybridized with bond angles of 120. Oxygen is sp3 hybridized. This molecule contains 28 valence electrons. There are some H–C–H bond angles of about 109  in the molecule.

Use the following to answer questions 34-36: Tetracyanoethylene has the skeleton shown here:

From its Lewis structure, determine the following. 34.

How many sigma bonds and how many pi bonds are in the molecule? A) 5 sigma and 9 pi B) 6 sigma and 8 pi C) 9 sigma and 7 pi D) 9 sigma and 9 pi E) 5 sigma and 8 pi

35.

How many of the atoms are sp2 hybridized? A) 2 B) 4 C) 6 D) 8 E) 10

36.

How many of the atoms are sp hybridized? A) 2 B) 4 C) 6 D) 8 E) 10

37.

Which of the following has the shortest N-O bond? A) NO3– B) NO+ C) N2 D) NO2– E) none of these

38.

Complete the Lewis structure for the following molecule.

CH3 O CH3 CH

C

C

N

This molecule has __________ sigma bonds and __________ pi bonds. A) B) C) D) E)

4, 5 6, 3 11, 5 13, 2 13, 3

39.

Which of the following statements is correct? A) A triple bond is composed of two  bonds and one  bond. B)  bonds result from the head-to-head overlap of atomic orbitals. C) Free rotation may occur about a double bond. D)  bonds have electron density on the internuclear axis. E) More than one of these statements are correct.

40.

As the bond order of a bond increases, its bond energy ______ and its bond length ______. A) increases, increases B) decreases, decreases C) increases, decreases D) decreases, increases

41.

If four orbitals on one atom overlap four orbitals on a second atom, how many molecular orbitals will form? A) 1 B) 4 C) 8 D) 16 E) none of these

42.

For which of the following diatomic molecules would the bond order become greater if an electron were removed, that is, if the molecule were converted to the positive ion in its ground state? A) B2 B) C2 C) P2 D) F2 E) Na2

43.

Which of the following species has the largest dissociation energy? A) O2 B) O2– C) O22– D) O2+ E) O22+

44.

Which of the following is paramagnetic? A) B2 B) C2 C) H2 D) N2 E) F2

45.

Order the following from shortest to longest bond: C 2, B2, H2, N2 A) H2, N2, C2, B2 B) N2, C2, B2, H2 C) C2, N2, H2, B2 D) C2, B2, H2, N2 E) none of these

46.

Which of the following statements is true? A) Electrons are never found in an antibonding MO. B) All antibonding MOs are higher in energy than the atomic orbitals of which they are composed. C) Antibonding MOs have electron density mainly outside the space between the two nuclei. D) None of these statements is true. E) Two of these statements are true.

47.

Which of the following is paramagnetic? A) O2– B) O2+ C) O2 D) N2 E) At least two of these are paramagnetic.

48.

How many electrons are involved in pi bonding in benzene, C 6H6? A) 12 B) 30 C) 3 D) 6 E) 18

49.

Which of the following statements about the CO32– ion is false? A) The orbitals on the carbon atom are sp 2 hybridized. B) The ion is expected to be diamagnetic. C) One C–O bond is shorter than the others. D) The ion has a total of 24 electrons. E) It has a planar molecular geometry.

50.

Which of the following should have the highest boiling point? A) Na2O B) HF C) NH3 D) N2 E) H2O

51.

Identify the major attractive force in HF. A) London dispersion forces B) dipole-dipole interactions C) hydrogen bonding D) ionic bonding E) none of these

52.

Identify the major attractive force in H2S. A) London dispersion forces B) dipole-dipole interactions C) hydrogen bonding D) ionic bonding E) none of these

53.

Identify the major attractive force in CaF 2. A) London dispersion forces B) dipole-dipole interactions C) hydrogen bonding D) ionic bonding E) none of these

54.

Identify the major attractive force in Ne. A) London dispersion forces B) dipole-dipole interactions C) hydrogen bonding D) ionic bonding E) none of these

55.

Which of the following compounds has the lowest boiling point? A) CH4 B) C2H6 C) C3H8 D) C4H10 E) C5H12

56.

Which of the following compounds has the highest boiling point? A) C2H6 B) CO C) H2 D) N2 E) Ne

57.

Which of the following compounds has the highest boiling point? A) CH4 B) H2O C) NF3 D) O2 E) He

58.

Which substance involves no intermolecular forces except London dispersion forces? A) K B) H2S C) NaF D) H2 E) HCl

59.

The elements of Group 5A, the nitrogen family, form compounds with hydrogen that have the boiling points listed below. SbH3 –17°C, AsH3 –55°C, PH3 –87°C, NH3 –33°C The first three elements illustrate a trend where the boiling point decreases as the mass decreases; however, ammonia (NH3) does not follow the trend because of A) B) C) D) E)

dipole-dipole attraction. metallic bonding. hydrogen bonding. London dispersion forces. ionic bonding.

60.

The resistance of a liquid to an increase in its surface area is called A) capillary action. B) surface tension. C) vapor pressure D) viscosity. E) none of these

61.

On the basis of your knowledge of bonding in liquids and solids, which of the following substances has the highest melting temperature? A) NaBr B) Br2 C) NO2 D) CF4 E) H2O

62.

Which of the following is the correct order of boiling points for NaNO 3, CH3OH, C2H6, and Ne? A) Ne < CH3OH < C2H6 < NaNO3 B) NaNO3 < CH3OH < C2H6 < Ne C) Ne < C2H6 < NaNO3 < CH3OH D) Ne < C2H6 < CH3OH < NaNO3 E) C2H6 < Ne < CH3OH < NaNO3

63.

In cubic closest-packed solids, what percentage of space is occupied by the spheres? A) 43.8% B) 52.4% C) 68.0% D) 74.0% E) none of these

64.

Which of the following is the smallest hole in a closest-packed lattice of spheres? A) trigonal B) tetrahedral C) cubic D) octahedral E) none of these

65.

Which substance can be described as cations bonded together by mobile electrons? A) Ag(s) B) S8(s) C) Kr(l) D) KCl(s) E) HCl(l)

66.

What is the net number of face-centered atoms contained in a face-centered cubic unit cell? A) 1 B) 3 C) 4 D) 6 E) none of these

Use the following to answer questions 67- 69: The molar volume of a certain form of solid lead is 18 cm 3/mol. Assuming cubic closest-packed structure, determine the following. 67.

The number of Pb atoms per unit cell A) 3 B) 4 C) 10 D) 12 E) 14

68.

The volume of a single cell A) 1.20  102 pm3 B) 1.20  104 pm3 C) 1.20  106 pm3 D) 1.20  108 pm3 E) none of these

69.

The radius of a Pb atom A) 1.74 pm B) 17.4 pm C) 174 pm D) 1740 pm E) none of these

70.

Which one of the following statements about solid Cu (face-centered cubic unit cell) is incorrect? A) It will conduct electricity. B) There are two atoms per unit cell. C) The number of atoms surrounding each Cu atom is 12. D) The solid has a cubic closest-packed structure. E) The length of a face diagonal is four times the Cu radius.

71.

Which of the following statements is(are) false? I. The hexagonal closest-packed structure is ABAB.... II. A body-centered cubic unit cell has four atoms per unit cell. III. For unit cells having the same edge length, a simple cubic structure would have a smaller density than a body-centered cube. IV. Atoms in a solid consisting of only one element would have six nearest neighbors if the crystal structure was a simple cubic array. A) B) C) D) E)

72.

I only II only II, III only I, IV II, III, IV

Aluminum metal crystallizes in a face-centered cubic structure. What is the relationship between the radius of an Al atom (r) and the length of an edge of the unit cell ( E)? A) r = E/2 B) C) D) E)

r  E/ 8 r  ( 3 / 4) E r = 2E r = 4E

73.

A metal crystallizes in a body-centered unit cell with an edge length of 2.12  102 pm. Assume the atoms in the cell touch along the cube diagonal. What will be the percentage of empty volume in the unit cell? A) 0.00% B) 26.0% C) 32.0% D) 68.0% E) 75.5%

74.

A metal crystallizes with a face-centered cubic lattice. The edge of the unit cell is 434 pm. What is the diameter of the metal atom? A) 376 pm B) 217 pm C) 307 pm D) 434 pm E) 614 pm

75.

Chromium metal crystallizes as a body-centered cubic lattice. If the atomic radius of Cr is 1.25 angstroms, what is the density of Cr metal in grams per cubic centimeter? A) 5.52 g/cm3 B) 7.18 g/cm3 C) 7.81 g/cm3 D) 2.76 g/cm3 E) 3.59 g/cm3

76.

You are given a small bar of an unknown metal, X. You find the density of the metal to be 10.5 g/cm3. An Xray diffraction experiment measures the edge of the unit cell as 409 pm. Assuming that the metal crystallizes in a face-centered cubic lattice, what is X most likely to be? A) Ag B) Rh C) Pt D) Pb E) none of these

77.

A certain solid substance that is very hard, has a high melting point, and is nonconducting unless melted is most likely to be A) I2 B) KCl C) NO2 D) H2O E) Cr

78.

The unit cell in a certain lattice consists of a cube formed by an anion at each corner, an anion in the center, and a cation at the center of each face. The unit cell contains a net A) 5 anions and 6 cations. B) 5 anions and 3 cations. C) 2 anions and 3 cations. D) 3 anions and 4 cations. E) 2 anions and 2 cations.

79.

A certain metal fluoride crystallizes in such a way that the fluoride ions occupy simple cubic lattice sites, while the metal atoms occupy the body centers of half the cubes. What is the formula for the metal fluoride? A) MF2 B) M2F C) MF D) MF8 E) none of these

80.

Sodium oxide (Na 2O) crystallizes in a structure in which the O2– ions are in a face-centered cubic lattice and the Na+ ions are in tetrahedral holes. What is the number of Na + ions in the unit cell? A) 2 B) 4 C) 6 D) 8 E) none of these

81.

In the unit cell of sphalerite, Zn2+ ions occupy half the tetrahedral holes in a face-centered cubic lattice of S2– ions. What is the number of formula units of ZnS in the unit cell? A) 5 B) 4 C) 3 D) 2 E) 1

82.

A p-type semiconductor A) is made by doping host atoms with atoms having more valence electrons than the host. B) is made by doping host atoms with atoms having fewer valence electrons than the host. C) has electrons that lie close in energy to the conduction bands. D) two of these E) none of these

83.

Which of the compounds below is an example of a network solid? A) S8(s) B) SiO2(s) C) MgO( s) D) NaCl(s) E) C25H52(s)

84.

Which of the following statements is true about p-type silicon? A) It is produced by doping Si with P or As. B) Electrons are the mobile charge carriers. C) It does not conduct electricity as well as pure Si. D) All are true. E) None is true.

85.

Doping Se with As would produce a(n) __________ semiconductor with __________ conductivity compared to pure Se. A) n-type, increased B) n-type, decreased C) p-type, increased D) p-type, decreased E) intrinsic, identical

86.

What is the vapor pressure of water at 100.0°C? A) 85 torr B) 760 torr C) 175 torr D) 1 torr E) More information is needed.

87.

Which of the following processes must exist in equilibrium with the condensation process when a measurement of vapor pressure is made? A) fusion B) evaporation C) sublimation D) boiling E) none of these

88.

Given below are the temperatures at which two different liquid compounds with the same empirical formula have a vapor pressure of 400 torr. Compound T (°C) dimethyl ether, CH 3-O-CH3 -37.8 ethanol, CH3CH2OH 63.5 Which of the following statements is false? A) B) C) D) E)

Increasing the temperature will increase the vapor pressure of both liquids. Intermolecular attractive forces are stronger in (liquid) ethanol than in (liquid) dimethyl ether. The normal boiling point of dimethyl ether will be higher than the normal boiling point of ethanol. The reason why the temperature at which the v...