AP Chemistry2 – ChemQuestion

Exercises on Bonding and Molecular Geometry

Exercise 1

Boron Trifluoride (BF₃)

Task: Determine the molecular geometry and hybridization.

해답 보기

Answer Explanation:

BF₃ has a trigonal planar geometry with sp² hybridization. Boron has three bonding pairs and no lone pairs.

Correct Answer: Trigonal Planar, sp²

Exercise 2

Phosphorus Trichloride (PCl₃)

Task: Determine the molecular geometry and hybridization.

해답 보기

Answer Explanation:

PCl₃ has a trigonal pyramidal geometry with sp³ hybridization. Phosphorus has three bonding pairs and one lone pair.

Correct Answer: Trigonal Pyramidal, sp³

Exercise 3

Triiodide Ion (I₃^–)

Task: Determine the molecular geometry and hybridization.

해답 보기

Answer Explanation:

I₃^– has a linear geometry with sp³d hybridization. The central iodine has two bonding pairs and three lone pairs.

Correct Answer: Linear, sp³d

Exercise 4

Nitrite Ion (NO₂^–)

Task: Determine the molecular geometry and hybridization.

해답 보기

Answer Explanation:

NO₂^– has a bent geometry with sp² hybridization. Nitrogen has two bonding pairs and one lone pair.

Correct Answer: Bent, sp²

Exercise 5

Nitrate Ion (NO₃^–)

Task: Determine the molecular geometry and hybridization.

해답 보기

Answer Explanation:

NO₃^– has a trigonal planar geometry with sp² hybridization. Nitrogen has three bonding pairs and no lone pairs.

Correct Answer: Trigonal Planar, sp²

Exercise 6

Which of the following compounds has the highest lattice energy?

(A) Sodium Chloride (NaCl)
(B) Lithium Fluoride (LiF)
(C) Magnesium Oxide (MgO)
(D) Potassium Bromide (KBr)

해답 보기

Answer Explanation:

Lattice energy increases with higher charges on the ions and smaller ionic radii. Magnesium oxide (MgO) has Mg²⁺ and O^2-, so it has a higher lattice energy than the other compounds.

Correct Answer: (C) MgO

Exercise 7

Which of the following substances is most likely to form an ionic bond based on its properties?

(A) Gold (Au)
(B) Sodium Chloride (NaCl)
(C) Methane (CH₄)
(D) Carbon Dioxide (CO₂)

View Answer

Answer Explanation:

Ionic bonds typically form between metals and nonmetals with strong electrostatic forces. NaCl is a classic ionic compound.

Correct Answer: (B)

Exercise 8

Which of the following statements best explains why metallic solids are good conductors of electricity?

(A) They have high lattice energies.
(B) Their electrons are localized and tightly bound to individual atoms.
(C) They consist of a lattice of cations surrounded by a sea of delocalized electrons.
(D) They form discrete molecules with strong intermolecular forces.

해답 보기

Answer Explanation:

Metallic solids have delocalized electrons that move freely through the lattice, enabling good electrical conductivity.

Correct Answer: (C)

Exercise 9

During a chemical reaction, bond breaking requires energy input while bond forming releases energy. Which scenario is correct?

(A) Breaking a covalent bond in methane is exothermic; forming an ionic bond in NaCl is endothermic.
(B) Breaking an ionic bond in NaCl is endothermic; forming a metallic bond in Cu is exothermic.
(C) Breaking a metallic bond in Fe is exothermic; forming a covalent bond in H₂O is endothermic.
(D) Breaking a hydrogen bond in H₂O is exothermic; forming a covalent bond in CO₂ is exothermic.

View Answer

Answer Explanation:

Bond breaking is endothermic, bond forming is exothermic. Option (B) is correct: Breaking ionic bond in NaCl = endothermic, forming metallic bond in Cu = exothermic.

Correct Answer: (B)

Exercise 10

Compare the bond strength of Lithium Fluoride (LiF) and Sodium Chloride (NaCl). Which compound has a stronger ionic bond and why?

(A) LiF has a stronger ionic bond because Li⁺ and F^– have higher charges than Na⁺ and Cl^–.
(B) NaCl has a stronger ionic bond because Na⁺ and Cl^– are larger ions.
(C) LiF has a stronger ionic bond due to smaller ionic radii and higher charge density.
(D) Both have similar bond strengths.

해답 보기

LiF has smaller ions, hence greater charge density and stronger electrostatic attraction.

Correct Answer: (C)

Exercise 11

Which molecular geometry corresponds to a molecule with two bonding pairs and two lone pairs on the central atom?

(A) Linear
(B) Trigonal Planar
(C) Tetrahedral
(D) Bent

해답 보기

Two bonding pairs + two lone pairs → Bent geometry (like H₂O).

Correct Answer: (D)

Exercise 12

Which of the following molecules has sp³ hybridization at the central atom?

(A) CO₂
(B) BF₃
(C) CH₄
(D) SO₃

해답 보기

CH₄ (methane) is sp³ with four bonding pairs on carbon.

Correct Answer: (C)

Exercise 13

Which of the following molecules has a see-saw molecular geometry?

(A) SF₄
(B) PF₅
(C) XeF₄
(D) BF₃

View Answer

SF₄ is see-saw (4 bonds, 1 lone pair on sulfur).
Correct Answer: (A)

Exercise 14

Which of the following best explains why covalent crystals like diamond have very high melting points?

(A) They consist of discrete molecules with weak IMF.
(B) They have a continuous network of strong covalent bonds.
(C) They contain delocalized electrons that facilitate metallic bonding.
(D) They are composed of ions held by electrostatic forces.

해답 보기

Covalent crystals have a continuous network of strong covalent bonds (e.g., diamond).

Correct Answer: (B)

Exercise 15

Which of the following properties is most characteristic of metallic bonding in a substance?

(A) High electrical conductivity in both solid and liquid states.
(B) High melting point but poor conductivity in solids.
(C) Low melting point and discrete molecules.
(D) Solubility in polar solvents like water.

View Answer

Metallic bonding is characterized by free electrons conduction in solids and liquids.

Correct Answer: (A)

Exercise 16

Which of the following molecules exhibits hydrogen bonding?

(A) CH₄
(B) H₂S
(C) NH₃
(D) CO₂

해답 보기

NH₃ forms hydrogen bonds (N—H with a lone pair on N).

Correct Answer: (C)

Exercise 17

Explain why Lithium (Li) has a stronger metallic bond compared to Sodium (Na).

(A) Li has more delocalized electrons.
(B) Li atoms are larger, so stronger attraction.
(C) Li has a higher effective nuclear charge, pulling electrons more strongly.
(D) Li forms interstitial alloys more readily.

해답 보기

Because Li is smaller and has a higher effective nuclear charge, it holds its electron sea more tightly, strengthening the metallic bond.

Correct Answer: (C)

Exercise 18

Which of the following substances is expected to conduct electricity in its solid state?

(A) Diamond (C)
(B) Sodium Chloride (NaCl)
(C) Graphite (C)
(D) Ice (H₂O)

해답 보기

Graphite conducts in solid state due to delocalized electrons in planes.

Correct Answer: (C)

Exercise 19

Which type of molecular geometry is associated with a molecule that has three bonding pairs and one lone pair on the central atom?

(A) Tetrahedral
(B) Trigonal Pyramidal
(C) Bent
(D) Trigonal Planar

해답 보기

3 bonding + 1 lone → Trigonal pyramidal (like NH₃).

Correct Answer: (B)

Exercise 20

Which of the following substances is an example of a network covalent solid, with very high melting point and hardness?

(A) Sodium Chloride (NaCl)
(B) Graphite (C)
(C) Methane (CH₄)
(D) Magnesium (Mg)

View Answer

Graphite is a network covalent solid (so is diamond). Option (B).

Correct Answer: (B)

Exercise 21

Which molecular geometry has bond angles of ~109.5°?

(A) Linear
(B) Trigonal Planar
(C) Tetrahedral
(D) Bent

해답 보기

Tetrahedral geometry has ~109.5° angles.

Correct Answer: (C)

Exercise 22

In the formation of an ionic bond between Mg and O, which is correct?

(A) Mg gains 2 e⁻, O loses 2 e⁻
(B) Mg loses 2 e⁻, O gains 2 e⁻
(C) Mg gains 1 e⁻, O loses 1 e⁻
(D) Mg shares 2 e⁻ with O

해답 보기

Mg → Mg²⁺, O → O^2-. So Mg loses 2, O gains 2.

Correct Answer: (B)

Exercise 23

During numbering, we see a mismatch, but continuing: Which statement about bond length & bond strength is correct?

(A) Shorter bond lengths → weaker bonds
(B) Longer bond lengths → stronger bonds
(C) Shorter bond lengths → stronger bonds
(D) Bond length & strength are independent

해답 보기

Shorter bonds are typically stronger.

Correct Answer: (C)

Exercise 24

Which type of IMF primarily accounts for water’s high boiling point?

(A) London dispersion
(B) Dipole-dipole
(C) Hydrogen bonding
(D) Ionic bonding

해답 보기

Water’s high boiling point is due to hydrogen bonds.

Correct Answer: (C)

Exercise 25

Why can graphite conduct electricity while diamond cannot?

(A) Graphite has discrete molecules; diamond has network bonds.
(B) Graphite has delocalized electrons; diamond does not.
(C) Diamond has higher lattice energy than graphite.
(D) Graphite forms ionic bonds; diamond forms covalent bonds.

해답 보기

Graphite has delocalized electrons in planar sheets, allowing conduction. Diamond lacks them.

Correct Answer: (B)

Exercise 26

What explains the difference in hardness between diamond & graphite?

(A) Diamond is layered; graphite is tetrahedral.
(B) Diamond has strong 3D covalent bonds; graphite has strong in-layer but weak interlayer forces.
(C) Graphite has stronger IMF than diamond.
(D) Graphite has a higher lattice energy than diamond.

해답 보기

Diamond is a 3D network covalent solid, very hard. Graphite has layered structure (weak forces between layers).

Correct Answer: (B)

Exercise 27

Why do ionic solids typically have higher melting points than molecular solids?

(A) Ionic solids have weaker forces.
(B) Ionic solids have strong electrostatic attractions.
(C) Molecular solids have a continuous covalent network.
(D) Molecular solids contain delocalized electrons.

해답 보기

Ionic solids are held by strong electrostatic forces between ions.

Correct Answer: (B)

Exercise 28

According to Coulomb’s Law, which factor does NOT directly affect ionic bond strength?

(A) The charges on the ions
(B) The distance between ions
(C) The number of valence electrons (outer electrons) per se
(D) The types of ions (which affects charge/radius)

View Answer

Coulomb’s Law depends on charge magnitude (q1q2) and distance (r), not directly the total # of valence electrons apart from how they form the ions.

Correct Answer: (C)

Exercise 29

Which compound contains both ionic and covalent bonds?

(A) NaCl
(B) CO₂
(C) NH₄NO₃
(D) CH₄

View Answer

Ammonium nitrate has ionic bonding between NH₄⁺ and NO₃^–, plus covalent bonds within those ions.

Correct Answer: (C)

Exercise 30

Which best explains why water (H₂O) has a higher boiling point than hydrogen sulfide (H₂S)?

(A) H₂O has stronger hydrogen bonding.
(B) H₂S has more polar bonds.
(C) H₂O has weaker IMF.
(D) H₂S is a network covalent solid.

해답 보기

Water forms strong hydrogen bonds; H₂S does not.

Correct Answer: (A)

Exercise 31

Which explains why magnesium (Mg) has a stronger metallic bond than lithium (Li)?

(A) Mg has more delocalized electrons (2 vs 1).
(B) Mg is larger, so stronger bond.
(C) Mg has higher ionization energy.
(D) Mg has lower electronegativity.

해답 보기

Magnesium can contribute two electrons to the “sea”, strengthening the metallic bond.

Correct Answer: (A)

Exercise 32

Based on Coulomb’s Law, which ionic compound has the greatest lattice energy?

(A) CaO
(B) AlN
(C) SrS
(D) KF

View Answer

AlN with Al³⁺ and N^3- yields higher charge product and smaller ions → highest lattice energy.

Correct Answer: (B)

Exercise 33

Which molecular geometry corresponds to sp³ hybridization and one lone pair?

(A) Trigonal Planar
(B) Tetrahedral
(C) Trigonal Pyramidal
(D) Linear

해답 보기

sp³ with 1 lone pair → trigonal pyramidal (like NH₃).

Correct Answer: (C)

Exercise 34

Why is silicon (Si) classified as a network covalent solid rather than a molecular solid?

(A) Si forms discrete Si₄ molecules.
(B) Si forms a 3D network of covalent bonds.
(C) Si has delocalized electrons like metals.
(D) Si exists as isolated atoms.

해답 보기

Silicon has a continuous 3D covalent network (like diamond).

Correct Answer: (B)

Exercise 35

Which statement about bond energy & bond length is accurate?

(A) Triple bonds are longer/weaker than single bonds.
(B) Double bonds are longer than single but lower bond energy.
(C) More shared pairs → shorter bond length & higher bond energy.
(D) All have same bond energy.

해답 보기

Increasing shared pairs = shorter length & stronger bond.

Correct Answer: (C)

Exercise 36

Which statement distinguishes interstitial vs. substitutional alloys?

(A) Interstitial: similar-size atoms replace each other; Substitutional: smaller fill holes.
(B) Substitutional: different-size fill holes; Interstitial: similar-size replace.
(C) Interstitial: different-size fill holes; Substitutional: comparable radii replace.
(D) Both exclusively have similar radii atoms.

해답 보기

Interstitial = smaller atoms filling holes; Substitutional = similar-size atoms replacing some metal atoms.

Correct Answer: (C)

Exercise 37

Arrange in order of highest to lowest lattice energy: MgO, LiF, NaCl, KBr.

(A) MgO > LiF > NaCl > KBr
(B) LiF > MgO > NaCl > KBr
(C) NaCl > MgO > LiF > KBr
(D) KBr > NaCl > LiF > MgO

해답 보기

MgO has highest (2+/2-), then LiF (small ions), then NaCl, then KBr.

Correct Answer: (A)

Exercise 38

Which molecule exhibits resonance due to delocalized electrons?

(A) CH₄
(B) C₂H₆
(C) C₆H₆ (Benzene)
(D) CCl₄

해답 보기

Benzene has resonance among ring double bonds.
Correct Answer: (C)

Exercise 39

How does bond polarity relate to molecular polarity?

(A) All molecules with polar bonds are polar.
(B) A molecule can be nonpolar even if it has polar bonds.
(C) Molecules with nonpolar bonds are always polar.
(D) Molecular polarity is unrelated to bond polarity.

View Answer

Dipoles can cancel if geometry is symmetrical. So a molecule with polar bonds can be nonpolar overall.

Correct Answer: (B)

Exercise 40

Which molecule has a trigonal pyramidal geometry and is polar due to a lone pair on the central atom?

(A) CCl₄
(B) NH₃
(C) BF₃
(D) H₂O

View Answer

NH₃ is trigonal pyramidal (3 bonds, 1 lone pair) and polar.

Correct Answer: (B)

Exercise 41

Which ion exhibits resonance due to delocalized electrons?

(A) NH₄⁺
(B) SO₄^2-
(C) OH^–
(D) Na⁺

View Answer

Sulfate (SO4 2-) has resonance among the S=O bonds.
Correct Answer: (B)

Exercise 42

Which best explains HF’s higher boiling point vs. other hydrogen halides (HCl, HBr, HI)?

(A) HF has stronger London dispersion forces.
(B) HF forms ionic bonds due to less shielding.
(C) HF forms strong hydrogen bonds via highly electronegative F.
(D) HF is smaller, enabling closer packing.

View Answer

HF has strong hydrogen bonding, whereas HCl/HBr/HI rely on weaker dipole or dispersion.

Correct Answer: (C)

Exercise 43

Which molecule is nonpolar yet has polar bonds?

(A) H₂O
(B) CO₂
(C) NH₃
(D) HF

View Answer

CO₂ is linear with bond dipoles canceling out, making it nonpolar.

Correct Answer: (B)

Exercise 44

Which molecular geometry has the highest number of electron pairs around the central atom?

(A) Linear
(B) Trigonal Planar
(C) Tetrahedral
(D) Octahedral

View Answer

Octahedral has six electron pairs around the center.

Correct Answer: (D)

Exercise 45

Why does diamond have a higher melting point than O₂?

(A) Diamond has stronger hydrogen bonds.
(B) Diamond is a 3D network solid; O₂ is just molecular with weak intermolecular forces.
(C) O₂ has heavier molecular weight.
(D) Diamond has delocalized electrons.

View Answer

Diamond is a network covalent solid, very strong bonds. O₂ has weak IMF.

Correct Answer: (B)

Exercise 46

Why do molecular solids generally have lower melting points than ionic solids?

(A) Molecular solids have stronger covalent bonds between molecules.
(B) Molecular solids have weaker intermolecular forces vs. strong ionic bonds.
(C) Ionic solids have larger ions.
(D) Ionic solids do not conduct electricity.

View Answer

Molecular solids rely on weaker IMF, while ionic solids have strong electrostatic attractions.

Correct Answer: (B)

Exercise 47

Which statement about network covalent solids and their conductivity is correct?

(A) Diamond conducts electricity as all electrons are free.
(B) Silicon is a conductor at room temp. due to free electrons.
(C) Graphite conducts (delocalized electrons), silicon & SiO₂ do not.
(D) SiO₂ conducts electricity due to a regular lattice.

View Answer

Graphite is unique among network covalents in that it conducts electricity via delocalized electrons. Diamond, Si, SiO₂ do not.

Correct Answer: (C)

Exercise 48

According to VSEPR, what is the geometry of SO₂?

(A) Linear
(B) Trigonal Planar
(C) Trigonal Pyramidal
(D) Bent

해답 보기

SO₂ has 2 bonding pairs + 1 lone pair → Bent geometry.

Correct Answer: (D)

Exercise 49

Which hybridization is associated with trigonal bipyramidal geometry?

(A) sp
(B) sp²
(C) sp³
(D) sp³d

View Answer

Trigonal bipyramidal → sp³d.

Correct Answer: (D)

Exercise 50

Which molecule has the lowest boiling point and why?

(A) H₂O
(B) CH₃OH (Methanol)
(C) H₂S
(D) NH₃

View Answer

H₂S has weaker H-bonding or dipoles than H₂O, CH₃OH, NH₃.

Correct Answer: (C)

Exercise 51

Which best describes the role of delocalized electrons in metallic bonding?

(A) They form covalent bonds.
(B) They localize between cations.
(C) They move freely, allowing electrical conductivity.
(D) They form ionic bonds.

View Answer

Delocalized electrons in metals roam freely, enabling conductivity.

Correct Answer: (C)

Exercise 52

Which molecule is expected to have the greatest bond polarity?

(A) Cl₂
(B) H₂O
(C) CO₂
(D) HF

View Answer

HF has the largest electronegativity difference (H-F).

Correct Answer: (D)

Exercise 53

Which statement is true about network covalent solids vs. molecular solids?

(A) Network covalents have lower melting points.
(B) Network covalents are typically soft & brittle.
(C) Network covalents do not conduct electricity (generally).
(D) Network covalents have strong bonding throughout the structure.

View Answer

They have strong covalent bonds throughout, leading to high melting points, hardness, etc.

Correct Answer: (D)

Exercise 54

Which compound is expected to conduct electricity in the solid state?

(A) Diamond (C)
(B) Silicon dioxide (SiO₂)
(C) Graphite (C)
(D) Sodium chloride (NaCl)

View Answer

Graphite can conduct as a solid. The others cannot (diamond, SiO2 do not conduct, NaCl is ionic—only in molten or aqueous form).

Correct Answer: (C)

Exercise 55

Which molecule is nonpolar despite having polar bonds?

(A) HCl
(B) CO₂
(C) NH₃
(D) HF

View Answer

CO2 is linear and dipoles cancel, so it is nonpolar.
Correct Answer: (B)

Exercise 56

Which best describes the hybridization of C in methane (CH₄)?

(A) sp
(B) sp²
(C) sp³
(D) dsp³

View Answer

CH₄ is tetrahedral → sp³.

Correct Answer: (C)

Exercise 57

Which compound primarily exhibits London dispersion forces in the liquid state?

(A) H₂O
(B) CH₄
(C) NH₃
(D) HF

View Answer

CH₄ is nonpolar, so only London dispersion forces.

Correct Answer: (B)

Exercise 58

Which molecule exhibits trigonal planar geometry?

(A) CH₄
(B) NH₃
(C) BF₃
(D) H₂O

View Answer

BF₃ has 3 bonds, no lone pairs on B → trigonal planar.

Correct Answer: (C)

Exercise 59

Why do network covalent solids generally have higher melting points than molecular solids?

(A) Network covalents have stronger IMFs.
(B) They have extensive covalent bonds throughout the structure.
(C) Molecular solids have bigger molecules with weaker bonds.
(D) Molecular solids have delocalized electrons, making them easier to melt.

View Answer

Network covalent = strong covalent network, not just IMFs.

Correct Answer: (B)

Exercise 60

Which molecule has a square planar geometry?

(A) XeF₄
(B) SF₄
(C) PF₅
(D) ClF₃

View Answer

XeF4 is square planar (4 bonds, 2 lone pairs on Xe).
Correct Answer: (A)

Exercise 61

Which molecule would have the strongest dipole-dipole interactions in liquid state?

(A) CCl₄
(B) NH₃
(C) SF₆
(D) CH₄

View Answer

NH₃ is polar with hydrogen bonding. Others are either nonpolar or less polar.

Correct Answer: (B)

Exercise 62

Why does NH₃ have a higher boiling point than CH₄?

(A) NH₃ has a larger mol. weight.
(B) NH₃ forms hydrogen bonds; CH₄ has only dispersion.
(C) CH₄ is polar, NH₃ is nonpolar.
(D) NH₃ has a symmetrical shape.

해답 보기

Ammonia forms H-bonds; methane does not → higher boiling point.

Correct Answer: (B)

Exercise 63

Which bonding type is responsible for the high melting point & hardness of diamond?

(A) Metallic
(B) Ionic
(C) Covalent network
(D) Van der Waals

View Answer

Diamond is a covalent network solid (sp³-bonded carbon network).

Correct Answer: (C)

Exercise 64

Which best explains why HF has a higher boiling point than HCl?

(A) HF has stronger hydrogen bonding due to F’s electronegativity.
(B) HCl has stronger dipoles.
(C) HF has bigger molecules.
(D) HCl forms a network covalent structure.

View Answer

Fluorine is highly electronegative → strong H-bonding in HF.

Correct Answer: (A)

Exercise 65

Which molecule is linear due to sp hybridization?

(A) BeCl₂
(B) SO₂
(C) NH₃
(D) H₂O

View Answer

BeCl₂ is sp & linear (2 bonds, no lone pairs on Be).

Correct Answer: (A)

Exercise 66

Which molecule exhibits hydrogen bonding in the liquid state?

(A) H₂S
(B) CH₄
(C) C₂H₅OH (Ethanol)
(D) CCl₄

해답 보기

Ethanol has an -OH group, enabling hydrogen bonding.
Correct Answer: (C)

Exercise 67

Why does MgO have a higher lattice energy than NaCl?

(A) MgO has bigger ions.
(B) MgO has ions with higher charges.
(C) NaCl has higher charge density.
(D) NaCl forms stronger metallic bonds.

View Answer

Mg²⁺ and O^2- → larger charge product than Na⁺, Cl^–.

Correct Answer: (B)

Exercise 68

Which molecule has a see-saw geometry due to one lone pair on the central atom?

(A) SF₄
(B) PCl₅
(C) ClF₃
(D) XeF₂

View Answer

SF4 has 4 bonding pairs, 1 lone pair → see-saw.
Correct Answer: (A)

Exercise 69

Which statement about geometry & hybridization is correct?

(A) All linear molecules have sp³.
(B) Tetrahedral molecules have sp³.
(C) Trigonal pyramidal molecules have sp².
(D) Bent molecules have sp.

View Answer

Tetrahedral → sp³ (e.g. CH₄).

Correct Answer: (B)

Exercise 70

Why does SiO₂ have a high melting point?

(A) Discrete molecules with strong H-bonds.
(B) Continuous 3D network of strong covalent bonds.
(C) Ionic bonds between Si⁴⁺ and O^2-.
(D) Metallic bonding with delocalized electrons.

View Answer

SiO₂ is a network covalent solid (like quartz) with high melting point.

Correct Answer: (B)

Exercise 71

Why can metals like Cu conduct electricity, but nonmetals like S cannot?

(A) Metals have free electrons, nonmetals do not.
(B) Nonmetals have more protons blocking electrons.
(C) Metals form ionic bonds, allowing electron flow.
(D) Nonmetals have delocalized electrons that block conduction.

View Answer

Metals have a “sea of electrons” that move freely; nonmetals lack such delocalized electrons.

Correct Answer: (A)

Exercise 72

Why do ionic bonds typically result in high melting and boiling points?

(A) Ionic bonds involve shared electrons (covalent).
(B) Strong electrostatic attraction between ions requires lots of energy to break.
(C) Delocalized electrons enhance ionic bonding.
(D) Ionic bonds are weaker than metallic bonds.

View Answer

Ionic bonds are strong electrostatic forces; large energy is needed to break the lattice.

Correct Answer: (B)

Exercise 73

Which best describes the intermolecular forces in SiO₂?

(A) Hydrogen bonds
(B) Dipole-dipole
(C) London dispersion
(D) Network covalent bonds

View Answer

SiO₂ is a network solid with covalent bonds, not “intermolecular” forces in the typical sense.

Correct Answer: (D)

Exercise 74

Which molecule exhibits a net dipole moment?

(A) CO₂
(B) BF₃
(C) NH₃
(D) C₂H₆

View Answer

NH₃ has a trigonal pyramidal shape, net dipole. CO₂, BF₃ are symmetrical, C₂H₆ is also nonpolar.

Correct Answer: (C)

Exercise 75

Which statement about ionic solids is correct?

(A) Good conductors in solid state.
(B) Low melting points due to weak forces.
(C) They are brittle and shatter under force.
(D) They are malleable like metals.

View Answer

Ionic solids are brittle, not malleable, have high melting points, and do not conduct as solids.

Correct Answer: (C)

Exercise 76

Which molecule is nonpolar due to its symmetrical geometry despite polar bonds?

(A) H₂O
(B) CCl₄
(C) NH₃
(D) HF

View Answer

CCl4 is tetrahedral, each C-Cl bond is polar but net dipole = 0
Correct Answer: (B)

Exercise 77

Why are hydrogen bonds stronger than London dispersion forces?

(A) H-bonds involve full electron sharing (covalent).
(B) H-bonds occur with highly electronegative atoms (N, O, F) creating strong dipoles.
(C) London forces are a type of hydrogen bond.
(D) H-bonds are weaker than dipole-dipole.

View Answer

Hydrogen bonding is a special, stronger form of dipole-dipole with high electronegativity differences.

Correct Answer: (B)

Exercise 78

Which molecule exhibits sp³ hybridization at the central atom?

(A) CO₂
(B) NH₃
(C) BF₃
(D) XeF₄

해답 보기

NH₃ is sp³.

Correct Answer: (B)

Exercise 79

Which network covalent solid has a layered structure, making it soft & slippery?

(A) Diamond
(B) Silicon
(C) Graphite
(D) Silicon dioxide

View Answer

Graphite is layered carbon, easily sheared.

Correct Answer: (C)

Exercise 80

Which of the following best explains why network covalent solids like diamond and silicon dioxide do not conduct electricity?

Options:

(A) They lack delocalized electrons.
(B) They have high lattice energies.
(C) They have symmetrical molecular geometries.
(D) They possess lone pairs of electrons.

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Answer Explanation:

Network covalent solids like diamond and silicon dioxide have all their electrons involved in strong covalent bonds, leaving no delocalized electrons available to conduct electricity.

Correct Answer: (A) They lack delocalized electrons.

Exercise 81

Which of the following best describes the process of bond formation in covalent bonds?

Options:

(A) Electrons are transferred from one atom to another.
(B) Electrons are shared between two atoms.
(C) Electrons become delocalized over a metal lattice.
(D) Electrons are removed entirely from a molecule.

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Answer Explanation:

Covalent bonds form when two atoms share electrons to achieve stable electron configurations. This differs from ionic bonds (electron transfer) or metallic bonds (delocalized electrons).

Correct Answer: (B) Electrons are shared between two atoms.

Exercise 82

Which of the following statements correctly describes the relationship between bond energy and potential energy during bond formation?

Options:

(A) Bond energy decreases as potential energy decreases.
(B) Bond energy is inversely related to potential energy.
(C) Bond energy is directly proportional to the difference in potential energy before and after bond formation.
(D) Bond energy and potential energy are unrelated concepts.

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Answer Explanation:

The bond energy (or bond dissociation energy) corresponds to the difference in potential energy between separated atoms and bonded atoms. A larger difference means a higher bond energy.

Correct Answer: (C)

Exercise 83

Which of the following best explains why methane (CH₄) has a tetrahedral geometry?

Options:

(A) It has sp² hybridization.
(B) It has sp³ hybridization with no lone pairs.
(C) It has sp hybridization with two lone pairs.
(D) It has dsp³ hybridization.

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Answer Explanation:

In CH₄, carbon forms four sp³-hybrid orbitals, each bonding to a hydrogen. No lone pairs remain on carbon, resulting in a tetrahedral shape (~109.5°).

Correct Answer: (B)

Exercise 84

Which of the following best describes the trend in bond strength among the hydrogen halides: HF, HCl, HBr, and HI?

Options:

(A) HF > HCl > HBr > HI
(B) HI > HBr > HCl > HF
(C) HCl > HF > HI > HBr
(D) HBr > HI > HF > HCl

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Answer Explanation:

As halide atoms increase in size (Cl → Br → I), bond length increases and bond strength decreases. HF is the shortest and strongest, then HCl, HBr, and finally HI as the weakest.

Correct Answer: (A)

Exercise 85

Which of the following best explains why hydrogen sulfide (H₂S) has a lower boiling point than hydrogen peroxide (H₂O₂)?

Options:

(A) H₂S has stronger hydrogen bonds than H₂O₂.
(B) H₂O₂ has stronger hydrogen bonds due to additional hydroxyl groups.
(C) H₂S is a larger molecule, resulting in weaker intermolecular forces.
(D) H₂O₂ has a lower molecular weight, leading to a lower boiling point.

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Answer Explanation:

Hydrogen peroxide (H₂O₂) can form more extensive hydrogen bonding because it has two —OH groups, resulting in stronger intermolecular forces and a higher boiling point than H₂S (which cannot form such strong hydrogen bonds).

Correct Answer: (B)

Exercise 86

Which of the following best explains the difference in electrical conductivity between metallic solids and molecular solids?

Options:

(A) Metallic solids have delocalized electrons that can move freely, while molecular solids do not.
(B) Molecular solids have delocalized electrons, while metallic solids do not.
(C) Both metallic and molecular solids have delocalized electrons, but molecular solids have stronger bonds.
(D) Neither metallic nor molecular solids have delocalized electrons.

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Answer Explanation:

Metals have a “sea of electrons” free to move throughout the lattice, enabling conductivity. Molecular solids, composed of discrete molecules with localized electrons, generally cannot conduct electricity in the solid state.

Correct Answer: (A)