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36 questions
Which of the following can be inferred from the diagram above that shows the dependence of potential energy on the internuclear distance between two atoms?
The atoms form a bond with a bond length of 25pm.
The atoms form a bond with a bond length of 75pm
75pm.
The net force between the atoms is attractive at 25pm
25pm.
The net force between the atoms is attractive at 75pm
75pm.
Based on the data in the tables above, which of the following statements provides the best prediction for the boiling point of NaCl ?
NaCl will have a lower boiling point than NaF because the coulombic attractions are weaker in NaCl than in NaF .
NaCl will have a boiling point between that of NaF and MgO because the covalent character of the bonds in NaCl is intermediate between that of MgO and NaF.
NaCl will have a higher boiling point than MgO because the ions are spaced farther apart in NaCl .
NaCl will have a higher boiling point than MgO because the energy required to transfer electrons from the anion to the cation is larger in NaCl than in MgO .
Has a central atom with less than an octet of electrons
H2O
NH3
BH3
CH4
SiH4
Has two lone pairs on the central atom.
H2O
NH3
BH3
CH4
SiH4
Predicted to have the largest bond angles.
H2O
NH3
BH3
CH4
SiH4
Has trigonal pyramidal molecular geomtry.
H2O
NH3
BH3
CH4
SiH4
The potential energy as a function of internuclear distance for three diatomic molecules, X2, Y2, and Z2, is shown in the graph above. Based on the data in the graph, which of the following correctly identifies the diatomic molecules, X2, Y2, and Z2?
X2 = H2 , Y2 = N2 , Z2= O2
X2 = N2 , Y2 = H2 , Z2= O2
X2 = O2 , Y2 = N2 , Z2= H2
X2 = O2 , Y2 = H2 , Z2= N2
The lattice energy of a salt is related to the energy required to separate the ions. For which of the following pairs of ions is the energy that is required to separate the ions largest? (Assume that the distance between the ions in each pair is equal to the sum of the ionic radii.)
Na+(g) and Cl−(g)
Cs+(g) and Br−(g)
Mg2+(g) and O2−(g)
Ca2+(g) and O2−(g)
NH3 reacts with BF3 to form a single species. Which of the following structural diagrams is the most likely representation of the product of the reaction?
The melting point of MgO is higher than that of NaF. Explanations for this observation include which of the following?
I. Mg2+ is more positively charged than Na+.
II. O2- is more negatively charged than F-.
III. The O2- ion is smaller than the F- ion.
I and II only
II only
I and III only
II and III only
I, II , and III
Which of the following is an isomer of CH3OCH3 ?
CH3CH3
CH3COOH
CH3CH2CH3
CH3CH2OCH2CH3
CH3CH2OH
On the basis of the information above, which of the following arranges the binary compounds in order of increasing bond polarity?
CH4 <SiCl4 < SF4
CH4 < SF4 <SiCl4
SF4 < CH4 <SiCl4
SF4 <SiCl4 < CH4
Which of the following compounds contains both ionic and covalent bonds?
SO3
NH4Cl
MgF2
H2S
C2H5OH
The elements C and Se have the same electronegativity value, 2.55. Which of the following claims about the compound that forms from C and Se is most likely to be true?
The carbon-to-selenium bond is unstable
The carbon-to-selenium bond is nonpolar covalent
The compound has an empirical formula of CSe
A molecule of the compound will have a partial negative charge on the carbon atom.
Which of the following correctly indicates whether the solid represented by the particulate model shown above conducts electricity and explains why or why not?
It conducts electricity because it is made of positive and negative ions.
It conducts electricity because it is made of particles of different sizes.
It conducts electricity because it is made of particles of different sizes.
It does not conduct electricity because there are small spaces between the particles.
The table above shows the structural formulas and molar masses for three different compounds. Which of the following is a list of the compounds in order of increasing boiling points?
Butane < 1-propanol < acetone
Butane < acetone < 1-propanol
Acetone = butane < 1-propanol
1-propanol < acetone < butane
Solid carbon tetrachloride, CCl4(s), is represented by the diagram above. The attractions between the CCl4
molecules that hold the molecules together in the solid state are best identified as
intermolecular attractions resulting from temporary dipoles
nonpolar covalent bonds
polar covalent bonds
intermolecular attractions resulting from permanent dipoles
At 298 K and 1 atm, Br2 is a liquid with a high vapor pressure, and Cl2 is a gas. Those observations provide evidence that under the given conditions, the
forces among Br2 molecules are stronger than those among Cl2 molecules
forces among Cl2 molecules are stronger than the Cl−Cl bond
Br−Br bond is stronger than the Cl−Cl bond
Cl−Cl bond is stronger than the Br−Br bond
The enthalpy of vaporization of water is 40.7 kJ/mol. Which of the following best explains why the enthalpy of vaporization of methane is less than that of water?
Methane does not exhibit hydrogen bonding, but water does.
Methane has weaker dispersion forces.
Methane has a smaller molar mass.
Methane has a much lower density.
Which statement best helps to explain the observation that NH3(l) boils at −28°C , whereas PH3(l)boils at −126°C ?
NH3 has hydrogen bonding that is stronger than the dipole-dipole forces in PH3.
NH3 has hydrogen bonding that is weaker than the dipole-dipole forces in PH3.
The dispersion forces in NH3 are stronger than the dipole-dipole forces in PH3.
The dispersion forces in NH3 are weaker than the dispersion forces in PH3.
The diagram above shows molecules of Br2 and I2 drawn to the same scale. Which of the following is the best explanation for the difference in the boiling points of liquid Br2 and I2, which are 59oC and 184oC, respectively?
I2 molecules have electron clouds that are more polarizable than those of Br2 molecules, thus London dispersion forces are stronger in liquid I2
The covalent bonds in I2 molecules are weaker than those in Br2 molecules.
Solid iodine is a network covalent solid, whereas solid bromine is a molecular solid.
Bromine has a greater electronegativity than iodine, thus there are stronger dipole-dipole forces in liquid bromine than in liquid iodine.
Contains 1 sigma (σ) and 2 pi (π) bonds
Li2
B2
N2
O2
F2
Has a bond order of 2
Li2
B2
N2
O2
F2
The diagram above is a molecular model of a gaseous diatomic element that is just above its boiling point. Intermolecular forces between the gas molecules will cause them to condense into the liquid phase if the temperature is lowered. Which of the following best describes how the model is limited in its depiction of the phenomenon?
It does not show how the temporary fluctuating dipoles of the molecular electron clouds result in a net force of attraction between the molecules.
It does not show how the interacting permanent dipoles of the molecules result in a net force of attraction between the molecules.
It does not show how the interactions between ions and the induced molecular dipoles result in a net force of attraction between the molecules.
It does not show how hydrogen bonds are constantly forming, breaking, and reforming, which results in a net force of attraction between the molecules.
According to the VSEPR model, the progressive decrease in the bond angles in the series of molecules CH4, NH3, and H2O is best accounted for by the
increasing number of unshared pairs of electrons
increasing electronegativity of the central atom
decreasing size of the central atom
increasing strength of the bonds
Which of the following has a zero dipole moment?
PF5
NO2
SO2
NH3
HCN
Which of the following species is NOT planar?
PCl3
BF3
ClF3
NO3-1
CO3-2
The BF3 molecule is nonpolar, whereas the NF3 molecule is polar. Which of the following statements accounts for the difference in polarity of the two molecules?
Unlike BF3, NF3 has a nonplanar geometry due to an unshared pair of electrons on the N atom.
NF3 is an ionic compound, whereas BF3 is a molecular compound.
N — F bonds are polar, whereas B — F bonds are nonpolar.
In NF3, each F is joined to N with multiple bonds, whereas in BF3 , each F is joined to B with single bonds.
The figure above shows that in solid hydrogen fluoride there are two different distances between H atoms and F atoms. Which of the following best accounts for the two different distances?
Difference in strength between covalent bonds and intermolecular attractions
Different isotopes of fluorine present in the samples
Uneven repulsions among nonbonding electron pairs
Accommodation of the necessary bond angles in the formation of the solid
Which of the following most likely describes the solid represented in the diagram above?
It is a brittle, water-soluble electrolyte that is a poor thermal and electrical conductor as a solid.
It is malleable and is an excellent thermal and electrical conductor as a solid.
It has a low melting point and is a poor thermal and electrical conductor as a solid.
It is soft and is a poor thermal and electrical conductor.
The boiling points of the elements helium, neon, argon, krypton, and xenon increase in that order. Which of the following statements accounts for this increase?
The London (dispersion) forces increase.
The London (dispersion) forces increase.
The dipole-dipole forces increase
The chemical reactivity increases.
The number of nearest neighbors increases.
Which of the following molecules has an angular (bent) geometry that is commonly represented as a resonance hybrid of two or more electron-dot structures?
CO2
O3
CH4
OF2
In the following diagrams, elements are represented by X
and Z, which form molecular compounds with one another. Which diagram represents a molecule that has a bent molecular geometry?
The diagram above shows two resonance structures for a molecule of C6H6. The phenomenon shown in the diagram best supports which of the following claims about the bonding in C6H6 ?
In the C6H6 molecule, all the bonds between the carbon atoms have the same length.
Because of variable bonding between its carbon atoms, C6H6 is a good conductor of electricity.
The bonds between carbon atoms in C6H6
are unstable, and the compound decomposes quickly.
The C6H6 molecule contains three single bonds between carbon atoms and three double bonds between carbon atoms.
Which of the following could be the identity of a white crystalline solid that exhibits the following properties?
C6H12O6
NaOH
SiO2
Cu
What is the hybridization of the carbon atoms in a molecule of ethyne, represented above?
sp
sp2
sp3
sp3d
sp2d
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