CM 2113 WANG TEST 1 AND 2 EXAMS – QUESTIONS
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Question 1
Which of the following statements correctly describes the relationship between bond
order and bond dissociation energy in diatomic molecules?
A. Bond dissociation energy decreases as bond order increases
B. Bond dissociation energy is independent of bond order
C. Bond dissociation energy increases as bond order increases
D. Bond dissociation energy increases as bond order decreases
🟢 C. Bond dissociation energy increases as bond order increases
🔴 Explanation: Bond order is directly proportional to bond dissociation energy. Higher
bond order indicates more shared electron pairs between atoms, resulting in stronger
bonds that require more energy to break. This relationship is observed in molecules such
as N₂ (triple bond, high dissociation energy) compared to F₂ (single bond, lower
dissociation energy).
Question 2
A chemist is analyzing an unknown compound and determines it has a pH of 3.2 in
aqueous solution. Which of the following conclusions is most accurate?
A. The solution contains equal concentrations of H⁺ and OH⁻
B. The solution is basic with excess OH⁻ ions
C. The solution is acidic with excess H⁺ ions
D. The solution is neutral with pH equal to 7
🟢 C. The solution is acidic with excess H⁺ ions
🔴 Explanation: A pH of 3.2 is significantly less than 7, indicating an acidic solution. In
acidic solutions, the concentration of hydronium ions (H₃O⁺) exceeds that of hydroxide
,ions (OH⁻). A pH of 3.2 corresponds to a hydrogen ion concentration of approximately 6.3
× 10⁻⁴ M, confirming the acidic nature of the solution.
Question 3
Which of the following factors does NOT affect the rate of a chemical reaction?
A. Temperature
B. Concentration of reactants
C. Presence of a catalyst
D. The color of the products
🟢 D. The color of the products
🔴 Explanation: The color of products is an observable property resulting from the reaction
but does not influence the reaction rate. Temperature, reactant concentration, and
catalysts all affect reaction kinetics by altering the frequency of molecular collisions, the
orientation of reacting species, or the activation energy barrier. Product color is a
consequence of the reaction, not a determining factor of its speed.
Question 4
In electrochemistry, which electrode serves as the site of reduction in a galvanic cell?
A. Anode
B. Cathode
C. Salt bridge
D. Electrolyte
🟢 B. Cathode
🔴 Explanation: In a galvanic cell, reduction occurs at the cathode, where electrons are
accepted by species from the external circuit. The anode is the site of oxidation, where
electrons are produced. The salt bridge maintains charge balance by allowing ion
migration, and the electrolyte provides the ionic medium for conduction, but neither serves
as the site of reduction.
,Question 5
According to Le Chatelier's Principle, what effect will increasing the pressure have on a
reaction system at equilibrium that produces fewer moles of gas than it consumes?
A. The equilibrium will shift toward the reactants
B. The equilibrium will shift toward the products
C. The equilibrium will remain unchanged
D. The reaction will stop completely
🟢 B. The equilibrium will shift toward the products
🔴 Explanation: When pressure is increased on a gaseous system at equilibrium, the system
shifts toward the side with fewer moles of gas to relieve the stress. If the products have
fewer moles of gas than the reactants, the equilibrium shifts toward the products to reduce
the total number of gas molecules, thereby decreasing the pressure.
Question 6
Which of the following orbitals is associated with the lowest energy level in a multi-
electron atom?
A. 3d
B. 4s
C. 3p
D. 2s
🟢 D. 2s
🔴 Explanation: In multi-electron atoms, orbital energies are determined by both principal
quantum number (n) and angular momentum quantum number (l). The 2s orbital (n=2,
l=0) has lower energy than 3p, 3d, and 4s orbitals due to its smaller principal quantum
number and lower angular momentum. The 2s orbital is filled before higher energy
orbitals according to the Aufbau principle.
, Question 7
A chemist adds 0.1 M HCl to a buffer solution containing acetic acid and sodium
acetate. Which of the following best describes the resulting change?
A. The pH increases significantly
B. The pH remains relatively constant
C. The pH decreases dramatically
D. The buffer capacity is completely exhausted
🟢 B. The pH remains relatively constant
🔴 Explanation: A buffer solution resists changes in pH when small amounts of acid or base
are added. The acetic acid-sodium acetate buffer neutralizes added HCl through the
reaction of acetate ions with H⁺ to form acetic acid. As long as the buffer capacity is not
exceeded, the pH remains relatively stable due to this neutralization mechanism.
Question 8
What is the hybridization state of the carbon atom in methane (CH₄)?
A. sp
B. sp²
C. sp³
D. sp³d
🟢 C. sp³
🔴 Explanation: The carbon atom in methane exhibits sp³ hybridization, resulting from the
mixing of one s orbital and three p orbitals to form four equivalent sp³ hybrid orbitals.
These orbitals arrange themselves in a tetrahedral geometry with bond angles of 109.5°,
consistent with the four equivalent C-H bonds observed in methane.
Question 9
Which of the following statements about activation energy is correct?
AND ANSWERS | VERIFIED AND WELL DETAILED
ANSWERS | PLUS RATIONALES | GUARANTEED PASS |
LATEST EXAM UPDATE
Question 1
Which of the following statements correctly describes the relationship between bond
order and bond dissociation energy in diatomic molecules?
A. Bond dissociation energy decreases as bond order increases
B. Bond dissociation energy is independent of bond order
C. Bond dissociation energy increases as bond order increases
D. Bond dissociation energy increases as bond order decreases
🟢 C. Bond dissociation energy increases as bond order increases
🔴 Explanation: Bond order is directly proportional to bond dissociation energy. Higher
bond order indicates more shared electron pairs between atoms, resulting in stronger
bonds that require more energy to break. This relationship is observed in molecules such
as N₂ (triple bond, high dissociation energy) compared to F₂ (single bond, lower
dissociation energy).
Question 2
A chemist is analyzing an unknown compound and determines it has a pH of 3.2 in
aqueous solution. Which of the following conclusions is most accurate?
A. The solution contains equal concentrations of H⁺ and OH⁻
B. The solution is basic with excess OH⁻ ions
C. The solution is acidic with excess H⁺ ions
D. The solution is neutral with pH equal to 7
🟢 C. The solution is acidic with excess H⁺ ions
🔴 Explanation: A pH of 3.2 is significantly less than 7, indicating an acidic solution. In
acidic solutions, the concentration of hydronium ions (H₃O⁺) exceeds that of hydroxide
,ions (OH⁻). A pH of 3.2 corresponds to a hydrogen ion concentration of approximately 6.3
× 10⁻⁴ M, confirming the acidic nature of the solution.
Question 3
Which of the following factors does NOT affect the rate of a chemical reaction?
A. Temperature
B. Concentration of reactants
C. Presence of a catalyst
D. The color of the products
🟢 D. The color of the products
🔴 Explanation: The color of products is an observable property resulting from the reaction
but does not influence the reaction rate. Temperature, reactant concentration, and
catalysts all affect reaction kinetics by altering the frequency of molecular collisions, the
orientation of reacting species, or the activation energy barrier. Product color is a
consequence of the reaction, not a determining factor of its speed.
Question 4
In electrochemistry, which electrode serves as the site of reduction in a galvanic cell?
A. Anode
B. Cathode
C. Salt bridge
D. Electrolyte
🟢 B. Cathode
🔴 Explanation: In a galvanic cell, reduction occurs at the cathode, where electrons are
accepted by species from the external circuit. The anode is the site of oxidation, where
electrons are produced. The salt bridge maintains charge balance by allowing ion
migration, and the electrolyte provides the ionic medium for conduction, but neither serves
as the site of reduction.
,Question 5
According to Le Chatelier's Principle, what effect will increasing the pressure have on a
reaction system at equilibrium that produces fewer moles of gas than it consumes?
A. The equilibrium will shift toward the reactants
B. The equilibrium will shift toward the products
C. The equilibrium will remain unchanged
D. The reaction will stop completely
🟢 B. The equilibrium will shift toward the products
🔴 Explanation: When pressure is increased on a gaseous system at equilibrium, the system
shifts toward the side with fewer moles of gas to relieve the stress. If the products have
fewer moles of gas than the reactants, the equilibrium shifts toward the products to reduce
the total number of gas molecules, thereby decreasing the pressure.
Question 6
Which of the following orbitals is associated with the lowest energy level in a multi-
electron atom?
A. 3d
B. 4s
C. 3p
D. 2s
🟢 D. 2s
🔴 Explanation: In multi-electron atoms, orbital energies are determined by both principal
quantum number (n) and angular momentum quantum number (l). The 2s orbital (n=2,
l=0) has lower energy than 3p, 3d, and 4s orbitals due to its smaller principal quantum
number and lower angular momentum. The 2s orbital is filled before higher energy
orbitals according to the Aufbau principle.
, Question 7
A chemist adds 0.1 M HCl to a buffer solution containing acetic acid and sodium
acetate. Which of the following best describes the resulting change?
A. The pH increases significantly
B. The pH remains relatively constant
C. The pH decreases dramatically
D. The buffer capacity is completely exhausted
🟢 B. The pH remains relatively constant
🔴 Explanation: A buffer solution resists changes in pH when small amounts of acid or base
are added. The acetic acid-sodium acetate buffer neutralizes added HCl through the
reaction of acetate ions with H⁺ to form acetic acid. As long as the buffer capacity is not
exceeded, the pH remains relatively stable due to this neutralization mechanism.
Question 8
What is the hybridization state of the carbon atom in methane (CH₄)?
A. sp
B. sp²
C. sp³
D. sp³d
🟢 C. sp³
🔴 Explanation: The carbon atom in methane exhibits sp³ hybridization, resulting from the
mixing of one s orbital and three p orbitals to form four equivalent sp³ hybrid orbitals.
These orbitals arrange themselves in a tetrahedral geometry with bond angles of 109.5°,
consistent with the four equivalent C-H bonds observed in methane.
Question 9
Which of the following statements about activation energy is correct?
