ACS PRACTICE EXAM 2 CORRECT
100%
From which of the following can the presence of discrete (quantized) energy levels in an
atom be inferred?
studies of the photoelectric effect
X-ray diffraction by crystals
atomic line spectra
electron diffraction by crystals - ANSWERatomic line spectra
Which ion contains 25 electrons?
Fe2+
Mn2+
Co2+
Cu2+ - ANSWERCo2+
What is the shape of orbitals containing 3𝑝 electrons? - ANSWERdumbbell shaped
What is the valence electron configuration for the element in period 4, group 5A? -
ANSWER4𝑠24𝑝3
Identify the number of neutrons in the I− 53 131 ion. - ANSWER78
What is the maximum number of electrons that can occupy a 𝑑(𝑥2−𝑦2) orbital? -
ANSWER2
Consider the following incomplete Lewis structure of HCN.
H-C-N
What feature will be present in the final, complete Lewis structure of the compound? -
ANSWERat least one triple bond
These two Lewis structures for carbon disulfide both satisfy the octet rule, but one is
preferred over the other. - ANSWERStructure B, because the formal charge on each
atom is 0.
Which of the following statements best describes molecules that have resonance
structures?
They are in rapid equilibrium with each other.
They contain resonating electrons.
They have multiple electron-dot formulas.
They contain hybrid orbitals. - ANSWERThey have multiple electron-dot formulas.
Which has the largest bond angle?
angle H−Be−H in BeH2
, angle F−C−F in CF4
angle Cl−B−Cl in BCl3
angle H−S−H in H2S - ANSWERangle H−Be−H in BeH2
Formic acid is found in the venom of bees and ants.
Based on the Lewis structure of formic acid, the approximate C−O−H bond angle is -
ANSWER109.5
Determine which set of species is arranged in order of increasing bond angle.
ClO−2<ClO+2<ClO2
ClO2<ClO−2<ClO2 +
ClO+2<ClO2<ClO2 -
ClO−2<ClO2<ClO2 + - ANSWERClO2-<ClO2<ClO2+
What is the mass percent of oxygen in Al2(SO4)3? - ANSWER56.1%
In acidic solution, the bromate ion, BrO−3, will oxidize Fe2+ to Fe3+ and form Br− ions.
The net ionic equation is
6H+(aq)+BrO−3(aq)+6Fe2+(aq)⟶Br−(aq)+6Fe3+(aq)+3H2O(l)
What volume of a 0.191 M BrO−3 solution is required to oxidize 67.1 mL of a 0.382 M
Fe2+ solution. - ANSWER22.4 mL
Calculate the enthalpy of reaction, Δ𝐻rxn, using the enthalpy of formation values
provided. - ANSWER−1234.8 kJ
Consider the following reaction.
2C2H6(g)+7O2(g)⟶4CO2(g)+6H2O(g)
What is the Δ𝐻∘ of the reaction? - ANSWER−2856.8 kJ/mol
The combustion of pyrite (FeS2) is represented by the following equation
4FeS2(s)+11O2(g)⟶2Fe2O3(s)+8SO2(g)
Δ𝐻∘rxn=−3.310×103 kJ/mol
The enthalpies of formation for Fe2O3 and SO2 are −824.2 kJ/mol and −296.8 kJ/mol,
respectively.
What is the enthalpy of formation for FeS2(s)? - ANSWER−178.2 kJ/mol
Consider this endothermic reaction at equilibrium
heat+𝑎A+𝑏B⇌𝑐C+𝑑D
where A, B, C, and D are the reactants or products, respectively and 𝑎,𝑏,𝑐, and 𝑑 are
the corresponding coefficients.
100%
From which of the following can the presence of discrete (quantized) energy levels in an
atom be inferred?
studies of the photoelectric effect
X-ray diffraction by crystals
atomic line spectra
electron diffraction by crystals - ANSWERatomic line spectra
Which ion contains 25 electrons?
Fe2+
Mn2+
Co2+
Cu2+ - ANSWERCo2+
What is the shape of orbitals containing 3𝑝 electrons? - ANSWERdumbbell shaped
What is the valence electron configuration for the element in period 4, group 5A? -
ANSWER4𝑠24𝑝3
Identify the number of neutrons in the I− 53 131 ion. - ANSWER78
What is the maximum number of electrons that can occupy a 𝑑(𝑥2−𝑦2) orbital? -
ANSWER2
Consider the following incomplete Lewis structure of HCN.
H-C-N
What feature will be present in the final, complete Lewis structure of the compound? -
ANSWERat least one triple bond
These two Lewis structures for carbon disulfide both satisfy the octet rule, but one is
preferred over the other. - ANSWERStructure B, because the formal charge on each
atom is 0.
Which of the following statements best describes molecules that have resonance
structures?
They are in rapid equilibrium with each other.
They contain resonating electrons.
They have multiple electron-dot formulas.
They contain hybrid orbitals. - ANSWERThey have multiple electron-dot formulas.
Which has the largest bond angle?
angle H−Be−H in BeH2
, angle F−C−F in CF4
angle Cl−B−Cl in BCl3
angle H−S−H in H2S - ANSWERangle H−Be−H in BeH2
Formic acid is found in the venom of bees and ants.
Based on the Lewis structure of formic acid, the approximate C−O−H bond angle is -
ANSWER109.5
Determine which set of species is arranged in order of increasing bond angle.
ClO−2<ClO+2<ClO2
ClO2<ClO−2<ClO2 +
ClO+2<ClO2<ClO2 -
ClO−2<ClO2<ClO2 + - ANSWERClO2-<ClO2<ClO2+
What is the mass percent of oxygen in Al2(SO4)3? - ANSWER56.1%
In acidic solution, the bromate ion, BrO−3, will oxidize Fe2+ to Fe3+ and form Br− ions.
The net ionic equation is
6H+(aq)+BrO−3(aq)+6Fe2+(aq)⟶Br−(aq)+6Fe3+(aq)+3H2O(l)
What volume of a 0.191 M BrO−3 solution is required to oxidize 67.1 mL of a 0.382 M
Fe2+ solution. - ANSWER22.4 mL
Calculate the enthalpy of reaction, Δ𝐻rxn, using the enthalpy of formation values
provided. - ANSWER−1234.8 kJ
Consider the following reaction.
2C2H6(g)+7O2(g)⟶4CO2(g)+6H2O(g)
What is the Δ𝐻∘ of the reaction? - ANSWER−2856.8 kJ/mol
The combustion of pyrite (FeS2) is represented by the following equation
4FeS2(s)+11O2(g)⟶2Fe2O3(s)+8SO2(g)
Δ𝐻∘rxn=−3.310×103 kJ/mol
The enthalpies of formation for Fe2O3 and SO2 are −824.2 kJ/mol and −296.8 kJ/mol,
respectively.
What is the enthalpy of formation for FeS2(s)? - ANSWER−178.2 kJ/mol
Consider this endothermic reaction at equilibrium
heat+𝑎A+𝑏B⇌𝑐C+𝑑D
where A, B, C, and D are the reactants or products, respectively and 𝑎,𝑏,𝑐, and 𝑑 are
the corresponding coefficients.
