CART (Chemistry Acceleration Readiness Test) Exam — Questions and Answers

Question 1: Which statement about a catalyst is correct?

It changes the equilibrium constant
It increases the activation energy
It provides an alternate pathway with lower activation energy (Correct answer)
It is consumed during the reaction

Correct answer: It provides an alternate pathway with lower activation energy

A catalyst works by providing an alternative reaction mechanism with a lower activation energy, speeding up the reaction without being consumed.

Question 2: Which conservation law requires that the mass numbers balance in a nuclear equation?

Conservation of momentum only
Conservation of charge only
Conservation of mass number and atomic number (Correct answer)
Conservation of energy only

Correct answer: Conservation of mass number and atomic number

In nuclear equations, both the total mass number (nucleons) and total atomic number (charge) must be equal on both sides of the equation.

Question 3: A solution is prepared by dissolving 20.0 g of glucose (C₆H₁₂O₆) in 80.0 g of water. What is the mass percent of glucose in this solution?

25.0%
100.0%
20.0% (Correct answer)
80.0%

Correct answer: 20.0%

Mass percent is calculated as (mass of solute / mass of solution) × 100%. The mass of the solute is 20.0 g of glucose. The mass of the solution is the mass of the solute plus the mass of the solvent (20.0 g + 80.0 g = 100.0 g). Therefore, the mass percent is (20.0 g / 100.0 g) × 100% = 20.0%.

Question 4: According to VSEPR theory, what is the molecular geometry of a molecule with a central atom that has two bonding pairs and two lone pairs of electrons?

Linear
Tetrahedral
Bent (Correct answer)
Trigonal pyramidal

Correct answer: Bent

Valence Shell Electron Pair Repulsion (VSEPR) theory predicts molecular shape based on minimizing repulsion between electron pairs. A central atom with four electron domains (two bonding pairs and two lone pairs) has a tetrahedral electron geometry. However, the molecular geometry is determined only by the positions of the atoms. The two lone pairs repel the bonding pairs more strongly, pushing the bonded atoms closer together and resulting in a bent or angular molecular shape, like in a water molecule (H₂O).

Question 5: An unknown element has two naturally occurring isotopes. The first isotope has a mass of 10.0129 amu and an abundance of 19.9%. The second isotope has a mass of 11.0093 amu and an abundance of 80.1%. What is the average atomic mass of this element?

10.51 amu
10.01 amu
10.81 amu (Correct answer)
11.01 amu

Correct answer: 10.81 amu

The average atomic mass is the weighted average of the masses of its isotopes. To calculate it, multiply the mass of each isotope by its fractional abundance and then sum the results: (10.0129 amu * 0.199) + (11.0093 amu * 0.801) = 1.9925671 amu + 8.8184493 amu = 10.8110164 amu. This value, rounded to two decimal places, is 10.81 amu (which corresponds to Boron).

Question 6: A flexible container holds 25.0 L of a gas at a pressure of 3.50 atm. If the temperature and number of moles of the gas remain constant, what is the new volume if the pressure is increased to 5.00 atm?

35.7 L
17.5 L (Correct answer)
87.5 L
12.5 L

Correct answer: 17.5 L

This question applies Boyle's Law, which states that for a fixed amount of gas at constant temperature, the pressure and volume are inversely proportional (P₁V₁ = P₂V₂). [3, 5] To find the new volume (V₂), we can rearrange the formula to V₂ = (P₁V₁) / P₂. Plugging in the values: V₂ = (3.50 atm * 25.0 L) / 5.00 atm = 17.5 L.

Question 7: A hand warmer packet releases heat as iron oxidizes. This is an example of a(n):

Endothermic chemical reaction
Endothermic physical change
Exothermic chemical reaction (Correct answer)
Isothermal process

Correct answer: Exothermic chemical reaction

Iron oxidation releases energy as heat, making hand warmers a real-world example of an exothermic chemical reaction.

Question 8: A student reacts 25.0 g of nitrogen (N₂) with 5.0 g of hydrogen (H₂) to produce ammonia (NH₃) according to the equation: N₂ + 3H₂ → 2NH₃. Which of the following statements is correct?

Hydrogen (H₂) is the limiting reactant, and excess nitrogen (N₂) remains. (Correct answer)
Both reactants are completely consumed.
Ammonia (NH₃) is the limiting reactant.
Nitrogen (N₂) is the limiting reactant, and excess hydrogen (H₂) remains.

Correct answer: Hydrogen (H₂) is the limiting reactant, and excess nitrogen (N₂) remains.

To find the limiting reactant, calculate the moles of each reactant and compare it to the stoichiometric ratio. Moles of N₂ = 25.0 g / 28.02 g/mol ≈ 0.892 mol. Moles of H₂ = 5.0 g / 2.02 g/mol ≈ 2.48 mol. The required mole ratio of N₂ to H₂ is 1:3. Moles of H₂ needed to react with all the N₂ is 0.892 mol N₂ × 3 = 2.676 mol H₂. Since we only have 2.48 mol of H₂, hydrogen is the limiting reactant and will be consumed first, leaving excess nitrogen.

Question 9: The density of mercury is 13.6 g/cm³. What is the mass in kilograms (kg) of 2.50 liters (L) of mercury? (Note: 1 L = 1000 cm³)

34,000 kg
0.0340 kg
3.40 kg
34.0 kg (Correct answer)

Correct answer: 34.0 kg

First, convert the volume from liters to cm³: 2.50 L × (1000 cm³/L) = 2500 cm³. Next, use the density formula (mass = density × volume) to find the mass in grams: mass = 13.6 g/cm³ × 2500 cm³ = 34,000 g. Finally, convert the mass from grams to kilograms: 34,000 g × (1 kg / 1000 g) = 34.0 kg. The final answer is reported to three significant figures, consistent with the initial measurements.

Question 10: A student needs to prepare 500.0 mL of a 0.500 M sodium chloride (NaCl) solution. How many grams of NaCl are required? (Molar Mass of NaCl ≈ 58.44 g/mol)

117 g
14.6 g (Correct answer)
58.4 g
29.2 g

Correct answer: 14.6 g

To find the mass of NaCl needed, first calculate the number of moles required using the molarity formula: Moles = Molarity × Volume (L). Moles = 0.500 mol/L × 0.5000 L = 0.250 moles. Then, convert moles to grams using the molar mass: Mass = Moles × Molar Mass. Mass = 0.250 mol × 58.44 g/mol = 14.61 g, which rounds to 14.6 g.

Question 11: What is the ground-state electron configuration for a sulfide ion (S²⁻)?

1s²2s²2p⁶3s²3p²
1s²2s²2p⁶3s²3p⁶ (Correct answer)
1s²2s²2p⁶3s²
1s²2s²2p⁶3s²3p⁴

Correct answer: 1s²2s²2p⁶3s²3p⁶

A neutral sulfur atom (S) has an atomic number of 16, so its electron configuration is 1s²2s²2p⁶3s²3p⁴. The sulfide ion (S²⁻) has gained two electrons. These two electrons are added to the outermost shell, which is the 3p subshell. This fills the 3p subshell completely, resulting in the electron configuration 1s²2s²2p⁶3s²3p⁶, which is isoelectronic with the noble gas Argon.

Question 12: Which of the following best describes a hydrogen bond?

A weak bond between a hydrogen atom in one molecule and a highly electronegative atom in another molecule (Correct answer)
A bond formed by the transfer of electrons from hydrogen to another atom
A strong bond between hydrogen and oxygen in a water molecule
A bond involving shared electrons between hydrogen and another atom

Correct answer: A weak bond between a hydrogen atom in one molecule and a highly electronegative atom in another molecule

A hydrogen bond is a weak intermolecular force that forms when a hydrogen atom, already covalently bonded to a highly electronegative atom (like O, N, or F) in one molecule, is attracted to another highly electronegative atom in a different molecule. This attraction is crucial for many biological and chemical properties, such as water's high boiling point.

Question 13: How many grams of CO₂ are produced when 44 grams of propane (C₃H₈) undergo complete combustion according to the equation: C₃H₈ + 5O₂ → 3CO₂ + 4H₂O? (Molar masses: C₃H₈ = 44 g/mol, CO₂ = 44 g/mol)

88 grams
176 grams
132 grams (Correct answer)
44 grams

Correct answer: 132 grams

To solve this, we first convert the given mass of propane (C₃H₈) to moles using its molar mass (44 g/mol), which gives 1 mole of C₃H₈. According to the balanced chemical equation, 1 mole of C₃H₈ produces 3 moles of CO₂. Therefore, 1 mole of propane will produce 3 moles of CO₂. Finally, we convert these 3 moles of CO₂ back to grams using its molar mass (44 g/mol), resulting in 3 * 44 = 132 grams of CO₂.

Question 14: Which type of radiation has the greatest penetrating power?

Neutron particles
Gamma rays (Correct answer)
Alpha particles
Beta particles

Correct answer: Gamma rays

Gamma rays are high-energy electromagnetic radiation with no mass or charge, allowing them to penetrate most materials except thick lead or concrete.

Question 15: Which of the following concentration units is temperature-dependent because it is based on the volume of the solution?

Molarity (M) (Correct answer)
Molality (m)
Mass percent (%)
Mole fraction (X)

Correct answer: Molarity (M)

Molarity is defined as moles of solute per liter of solution. Since the volume of a solution can change with temperature (expand when heated, contract when cooled), molarity is a temperature-dependent unit. Molality, mass percent, and mole fraction are all based on mass or moles, which are not affected by temperature changes.

Question 16: A reaction with a negative ΔH value is classified as:

Exothermic (Correct answer)
Isothermal
Endothermic
Adiabatic

Correct answer: Exothermic

A negative ΔH means the system releases heat to the surroundings, making the reaction exothermic.

Question 17: What is the charge of an electron?

Positive
Neutral
Negative (Correct answer)
Variable

Correct answer: Negative

Electrons are fundamental subatomic particles that carry a single negative elementary charge. This negative charge is crucial for their role in forming chemical bonds and interacting with other atoms.

Question 18: Consider the following reversible reaction: HCO₃⁻(aq) + H₂O(l) ⇌ H₂CO₃(aq) + OH⁻(aq) Which of the following represents a Brønsted-Lowry conjugate acid-base pair?

H₂O and OH⁻ (Correct answer)
HCO₃⁻ and H₂O
HCO₃⁻ and OH⁻
H₂O and H₂CO₃

Correct answer: H₂O and OH⁻

A conjugate acid-base pair consists of two species that differ by a single proton (H⁺). In this reaction, H₂O acts as an acid by donating a proton to become its conjugate base, OH⁻. Therefore, H₂O and OH⁻ form a conjugate acid-base pair. The other pair is HCO₃⁻ (base) and H₂CO₃ (its conjugate acid).

Question 19: A student prepares a solution of hydrochloric acid (HCl), a strong acid, with a concentration of 0.001 M. What is the pH of this solution?

-3
1
11
3 (Correct answer)

Correct answer: 3

The pH of a solution is calculated using the formula pH = -log[H⁺]. Because HCl is a strong acid, it completely dissociates in water, so the hydrogen ion concentration [H⁺] is equal to the molarity of the acid. Therefore, pH = -log(0.001) = -log(10⁻³) = 3.

Question 20: The reaction between aqueous silver nitrate and aqueous sodium chloride produces solid silver chloride and aqueous sodium nitrate. How is this reaction best classified? AgNO₃(aq) + NaCl(aq) → AgCl(s) + NaNO₃(aq)

Double Displacement (Precipitation) (Correct answer)
Single Displacement
Decomposition
Synthesis

Correct answer: Double Displacement (Precipitation)

This reaction is a double displacement (or metathesis) reaction because the cations (Ag⁺ and Na⁺) and anions (NO₃⁻ and Cl⁻) from the two reactant compounds exchange partners to form two new compounds. Since one of the products, AgCl, is an insoluble solid (a precipitate), it is also specifically classified as a precipitation reaction.

Question 21: Which type of bond is formed when atoms share electrons?

Covalent bond (Correct answer)
Ionic bond
Metallic bond
Hydrogen bond

Correct answer: Covalent bond

A covalent bond is formed when two atoms share one or more pairs of electrons to achieve a stable electron configuration, typically an octet. This sharing occurs predominantly between nonmetal atoms and results in the formation of molecules.

Question 22: In a laboratory experiment, the reaction of 15.0 g of aluminum (Al) with excess hydrochloric acid (HCl) produced 1.55 g of hydrogen gas (H₂). What is the percent yield of hydrogen? The balanced equation is: 2Al(s) + 6HCl(aq) → 2AlCl₃(aq) + 3H₂(g)

1.68%
92.3% (Correct answer)
88.6%
10.3%

Correct answer: 92.3%

First, calculate the theoretical yield. Moles of Al = 15.0 g / 26.98 g/mol ≈ 0.556 mol. From the 2:3 mole ratio between Al and H₂, moles of H₂ = 0.556 mol Al × (3 mol H₂ / 2 mol Al) = 0.834 mol H₂. Mass of H₂ (theoretical) = 0.834 mol × 2.02 g/mol = 1.68 g. The percent yield is (Actual Yield / Theoretical Yield) × 100 = (1.55 g / 1.68 g) × 100 ≈ 92.3%.

Question 23: Which of the following is a balanced equation for the combustion of methane (CH₄)?

CH₄ + 3O₂ → 2CO₂ + 2H₂O
CH₄ + O₂ → CO₂ + H₂O
CH₄ + 2O₂ → CO₂ + 2H₂O (Correct answer)
CH₄ + O₂ → CO + H₂O

Correct answer: CH₄ + 2O₂ → CO₂ + 2H₂O

To balance the combustion of methane (CH₄), the number of atoms for each element must be equal on both sides of the equation. One carbon atom on the left requires one CO₂ on the right. Four hydrogen atoms on the left require two H₂O on the right (2*2=4). This then results in four oxygen atoms on the right (2 from CO₂ + 2 from 2H₂O), which means two O₂ molecules are needed on the left (2*2=4).

Question 24: What is the name of the polyatomic ion with the formula ClO₂⁻?

Perchlorate
Chlorite (Correct answer)
Chlorate
Hypochlorite

Correct answer: Chlorite

This question requires knowledge of the nomenclature for polyatomic oxyanions. The series of chlorine-oxygen anions follows a pattern. ClO₄⁻ is perchlorate, ClO₃⁻ is chlorate, ClO₂⁻ is chlorite, and ClO⁻ is hypochlorite. The '-ate' suffix is used for the ion with more oxygen atoms, and the '-ite' suffix for the ion with fewer oxygen atoms. The 'per-' prefix indicates one more oxygen than the '-ate' ion, and the 'hypo-' prefix indicates one less oxygen than the '-ite' ion.

Question 25: A common speed limit in a residential area is 25 miles per hour (mph). What is this speed in meters per second (m/s)? (Given: 1 mile ≈ 1609 meters, 1 hour = 3600 seconds)

0.0069 m/s
56 m/s
40 m/s
11 m/s (Correct answer)

Correct answer: 11 m/s

This is a unit conversion problem that can be solved using dimensional analysis. Start with the given speed and multiply by conversion factors to cancel the unwanted units and introduce the desired units: (25 miles / 1 hour) × (1609 meters / 1 mile) × (1 hour / 3600 seconds). After calculating (25 × 1609) / 3600, the result is approximately 11.17 m/s. Since the original speed (25 mph) has two significant figures, the answer should be rounded to two significant figures, giving 11 m/s.

Question 26: What is the law that states that mass is neither created nor destroyed in a chemical reaction?

Law of Conservation of Energy
Law of Multiple Proportions
Law of Definite Proportions
Law of Conservation of Mass (Correct answer)

Correct answer: Law of Conservation of Mass

The Law of Conservation of Mass states that in any closed system, mass is neither created nor destroyed during a chemical reaction. This fundamental law means that the total mass of the reactants must equal the total mass of the products.

Question 27: If 25.0 mL of a 4.00 M stock solution of HCl is diluted with water to a final volume of 200.0 mL, what is the molarity of the resulting diluted solution?

1.00 M
2.00 M
0.500 M (Correct answer)
8.00 M

Correct answer: 0.500 M

This is a dilution problem that can be solved using the formula M₁V₁ = M₂V₂, where M₁ and V₁ are the initial molarity and volume, and M₂ and V₂ are the final molarity and volume. (4.00 M)(25.0 mL) = M₂(200.0 mL). Solving for M₂ gives: M₂ = (4.00 M × 25.0 mL) / 200.0 mL = 0.500 M.

Question 28: Which of the following best describes the mass number of an atom?

The number of protons in the nucleus
The total number of electrons in an atom
The sum of the protons and neutrons in the nucleus (Correct answer)
The average mass of all isotopes of an element

Correct answer: The sum of the protons and neutrons in the nucleus

The mass number (A) of an atom represents the total count of protons and neutrons residing in its nucleus. It provides an approximate measure of the atom's mass in atomic mass units, as electrons contribute negligibly to the overall mass.

Question 29: If a radioactive sample has a half-life of 5 years, what fraction of the original sample remains after 15 years?

1/8 (Correct answer)
1/16
1/2
1/4

Correct answer: 1/8

15 years = 3 half-lives; after each half-life the sample halves: (1/2)^3 = 1/8 of the original remains.

Question 30: In a laboratory neutralization reaction, aqueous sulfuric acid (H₂SO₄) is reacted with aqueous potassium hydroxide (KOH). What are the two products formed in this reaction?

Potassium hydride (KH) and sulfurous acid (H₂SO₃)
Potassium sulfate (K₂SO₄) and water (H₂O) (Correct answer)
Dipotassium oxide (K₂O) and hydrogen sulfide (H₂S)
Potassium sulfite (K₂SO₃) and dihydrogen peroxide (H₂O₂)

Correct answer: Potassium sulfate (K₂SO₄) and water (H₂O)

A neutralization reaction between an acid and a base produces a salt and water. In this case, the acid (H₂SO₄) and the base (KOH) react. The cation from the base (K⁺) combines with the anion from the acid (SO₄²⁻) to form the salt potassium sulfate (K₂SO₄). The hydrogen ion from the acid (H⁺) combines with the hydroxide ion from the base (OH⁻) to form water (H₂O).

Question 31: A sample of 0.50 moles of an ideal gas is held in a 10.0 L container at a temperature of 298 K. What is the pressure of the gas? (R = 0.0821 L·atm/mol·K)

12.2 atm
0.82 atm
1.22 atm (Correct answer)
2.45 atm

Correct answer: 1.22 atm

This problem requires the use of the Ideal Gas Law, PV = nRT. [9, 23] To find the pressure (P), we can rearrange the equation to P = nRT / V. Plugging in the given values: P = (0.50 mol * 0.0821 L·atm/mol·K * 298 K) / 10.0 L. This calculation results in a pressure of 1.22 atm.

Question 32: A rigid 10.0 L container holds a mixture of nitrogen gas (N₂) and oxygen gas (O₂). The partial pressure of the nitrogen is 0.75 atm and the partial pressure of the oxygen is 0.25 atm. What is the total pressure inside the container?

0.75 atm
0.50 atm
Cannot be determined from the information given.
1.00 atm (Correct answer)

Correct answer: 1.00 atm

This scenario is an application of Dalton's Law of Partial Pressures. This law states that the total pressure exerted by a mixture of non-reacting gases is equal to the sum of the partial pressures of the individual gases (P_total = P₁ + P₂ + ...). [10, 11, 21] In this case, P_total = P_N₂ + P_O₂ = 0.75 atm + 0.25 atm = 1.00 atm.

Question 33: Which of the following statements is NOT a postulate of the Kinetic Molecular Theory of ideal gases?

Collisions between gas particles are perfectly elastic, meaning no kinetic energy is lost.
The average kinetic energy of gas particles is directly proportional to the absolute temperature (in Kelvin).
The volume of the gas particles themselves is significant compared to the total volume of the container. (Correct answer)
Gas particles are in constant, random, straight-line motion.

Correct answer: The volume of the gas particles themselves is significant compared to the total volume of the container.

The Kinetic Molecular Theory of ideal gases includes several key postulates. One of these is that the volume of the individual gas particles is considered negligible compared to the vast empty space between them. [4, 12] Therefore, the statement that the particle volume is significant contradicts this fundamental assumption of an ideal gas.

Question 34: Which of the following has the highest specific heat capacity?

Copper (0.39 J/g·°C)
Iron (0.45 J/g·°C)
Aluminum (0.90 J/g·°C)
Water (4.18 J/g·°C) (Correct answer)

Correct answer: Water (4.18 J/g·°C)

Water has a specific heat of 4.18 J/(g·°C), far higher than common metals, making it an excellent thermal reservoir.

Question 35: Which of the following single displacement reactions will occur spontaneously according to the metal activity series?

Zn(s) + CuSO₄(aq) → (Correct answer)
Cu(s) + AlCl₃(aq) →
Ag(s) + HCl(aq) →
Fe(s) + MgCl₂(aq) →

Correct answer: Zn(s) + CuSO₄(aq) →

A single displacement reaction occurs when a more reactive element displaces a less reactive element from a compound. According to the activity series, zinc (Zn) is more reactive than copper (Cu), so it will displace copper from copper(II) sulfate. In the other options, the elemental metals (Cu, Ag, Fe) are less reactive than the metal ions they would need to displace (Al³⁺, H⁺, Mg²⁺), so no reaction will occur.

Question 36: Under which of the following conditions would a real gas be expected to deviate MOST from ideal gas behavior?

Low temperature and low pressure
High temperature and high pressure
Low temperature and high pressure (Correct answer)
High temperature and low pressure

Correct answer: Low temperature and high pressure

Real gases deviate from ideal behavior because the assumptions of the Kinetic Molecular Theory (negligible particle volume and no intermolecular forces) break down. [23] At low temperatures, gas particles move slower and intermolecular forces become more significant. At high pressures, the particles are forced closer together, making their individual volumes a more significant fraction of the total container volume. Therefore, the combination of low temperature and high pressure causes the most significant deviation from ideal behavior.

Question 37: Isotopes of an element differ in the number of which subatomic particle?

Neutrons (Correct answer)
Positrons
Protons
Electrons

Correct answer: Neutrons

Isotopes are atoms of the same element, meaning they share the same number of protons and thus the same atomic number. They differ in their mass number because they have varying numbers of neutrons in their nucleus, leading to different atomic masses.

Question 38: An atom has an atomic number of 15 and a mass number of 31. How many protons, neutrons, and electrons does a neutral atom of this element have?

16 protons, 15 neutrons, 16 electrons
15 protons, 15 neutrons, 16 electrons
31 protons, 15 neutrons, 31 electrons
15 protons, 16 neutrons, 15 electrons (Correct answer)

Correct answer: 15 protons, 16 neutrons, 15 electrons

The atomic number (Z) is equal to the number of protons. For a neutral atom, the number of electrons is equal to the number of protons. The mass number (A) is the sum of protons and neutrons. Therefore, protons = 15, electrons = 15, and neutrons = Mass Number - Protons = 31 - 15 = 16.

Question 39: What type of bond involves the electrostatic attraction between delocalized electrons and positively charged metal ions?

Ionic bond
Covalent bond
Metallic bond (Correct answer)
Hydrogen bond

Correct answer: Metallic bond

A metallic bond is characterized by the electrostatic attraction between a 'sea' of delocalized valence electrons and the positively charged metal ions. These free-moving electrons are responsible for the unique properties of metals, such as high electrical conductivity and malleability.

Question 40: Which of the following correctly names the covalent compound N₂O₅?

Nitrogen oxide
Dinitrogen pentoxide (Correct answer)
Nitrogen(V) oxide
Dinitrogen oxide

Correct answer: Dinitrogen pentoxide

For binary covalent compounds (compounds between two nonmetals), Greek prefixes are used to indicate the number of each type of atom. The prefix for two is 'di-' and the prefix for five is 'penta-'. Therefore, N₂O₅ is named dinitrogen pentoxide. The other names are incorrect because they either omit the prefixes or use the stock system (Roman numerals), which is reserved for ionic compounds with variable-charge metals.

Question 41: Which type of radiation is stopped most easily and cannot penetrate human skin?

Alpha particles (Correct answer)
Gamma rays
X-rays
Beta particles

Correct answer: Alpha particles

Alpha particles are large, heavy, and doubly charged; they lose energy quickly and are stopped by a few centimeters of air or a sheet of paper.

Question 42: Which of the following statements best describes the trend of first ionization energy on the periodic table?

It increases down a group and decreases from left to right across a period.
It increases down a group and increases from left to right across a period.
It decreases down a group and increases from left to right across a period. (Correct answer)
It decreases down a group and decreases from left to right across a period.

Correct answer: It decreases down a group and increases from left to right across a period.

First ionization energy is the energy required to remove the outermost electron from a neutral atom. It decreases down a group because the valence electrons are in higher energy levels, are farther from the nucleus, and experience more shielding, making them easier to remove. It increases from left to right across a period because the increasing effective nuclear charge holds the electrons more tightly, requiring more energy to remove one.

Question 43: What type of bond is created when one atom donates an electron to another atom?

Covalent bond
Ionic bond (Correct answer)
Van der Waals bond
Metallic bond

Correct answer: Ionic bond

An ionic bond is formed when one atom completely transfers one or more electrons to another atom, resulting in the formation of oppositely charged ions. These cations (positive) and anions (negative) are then held together by strong electrostatic attraction.

Question 44: A chemist is analyzing a substance and finds that it is composed of atoms that share electrons to form discrete molecules. The electronegativity difference between the bonded atoms is 1.2. How should this substance's bonding be classified?

Polar covalent (Correct answer)
Ionic
Metallic
Nonpolar covalent

Correct answer: Polar covalent

The type of bond between two atoms can be predicted by their electronegativity difference. A difference between approximately 0.4 and 1.7 indicates a polar covalent bond, where electrons are shared unequally, creating partial positive and negative charges. An electronegativity difference greater than 1.7 typically results in an ionic bond, while a difference less than 0.4 results in a nonpolar covalent bond. Metallic bonding involves a 'sea' of delocalized electrons and is not determined by this metric.

Question 45: At chemical equilibrium, which of the following is true?

The concentrations of reactants and products are equal
All reactants have been consumed
The reaction has stopped completely
The forward and reverse reaction rates are equal (Correct answer)

Correct answer: The forward and reverse reaction rates are equal

At equilibrium, the forward and reverse reactions occur at the same rate, so concentrations remain constant but are not necessarily equal.

Question 46: Reaction rate is defined as the change in concentration of a reactant or product per unit of:

Time (Correct answer)
Pressure
Volume
Temperature

Correct answer: Time

Reaction rate measures how quickly concentration changes over time, expressed as Δ[concentration]/Δtime.

Question 47: A chemist completely reacts 13.08 g of zinc metal (Zn) with an excess of hydrochloric acid (HCl) according to the balanced equation: Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g). What volume of hydrogen gas (H₂) is produced at Standard Temperature and Pressure (STP)? (Molar mass of Zn = 65.38 g/mol)

1.12 L
2.24 L
4.48 L (Correct answer)
8.96 L

Correct answer: 4.48 L

First, convert the mass of zinc to moles: 13.08 g Zn / 65.38 g/mol = 0.200 mol Zn. The mole ratio between Zn and H₂ is 1:1, so 0.200 mol of H₂ is produced. At STP (0°C and 1 atm), one mole of any ideal gas occupies 22.4 L. Therefore, the volume is 0.200 mol H₂ × 22.4 L/mol = 4.48 L.

Question 48: According to the Brønsted-Lowry theory, which of the following best describes an acid?

A substance that can donate a proton (H⁺). (Correct answer)
A substance that increases the hydroxide ion concentration in water.
A substance that can accept a proton (H⁺).
A substance that can accept a pair of electrons.

Correct answer: A substance that can donate a proton (H⁺).

The Brønsted-Lowry theory defines an acid as a species that donates a proton (a hydrogen ion, H⁺) and a base as a species that accepts a proton. An electron pair acceptor is a Lewis acid, and a substance that increases [OH⁻] is an Arrhenius base.

Question 49: In a chemical reaction, the substances that are present at the beginning and undergo change are called:

Products
Reactants (Correct answer)
Catalysts
Inhibitors

Correct answer: Reactants

In a chemical reaction, the substances that are present at the beginning and undergo a chemical change are called reactants. These starting materials are consumed during the reaction to form new substances, which are known as products.

Question 50: In beta-minus decay, a neutron is converted inside the nucleus into:

An alpha particle and a gamma ray
Two protons and a positron
A proton and an emitted positron
A proton and an emitted electron (beta particle) (Correct answer)

Correct answer: A proton and an emitted electron (beta particle)

Beta-minus decay: n → p + e⁻ + antineutrino; the proton stays in the nucleus and the electron (beta particle) is emitted.

Question 51: What is the oxidation number of manganese (Mn) in the permanganate ion, MnO₄⁻?

+7 (Correct answer)
+4
+8
-1

Correct answer: +7

The sum of the oxidation numbers in a polyatomic ion must equal the charge of the ion. The charge on the permanganate ion is -1. The oxidation number of oxygen is typically -2. Let 'x' be the oxidation number of Mn. The equation is: x + 4(-2) = -1. Solving for x gives x - 8 = -1, so x = +7.

Question 52: A chemical reaction must be performed at a temperature of 398 K. What is this temperature in degrees Celsius (°C)?

273°C
671°C
-125°C
125°C (Correct answer)

Correct answer: 125°C

The formula to convert from Kelvin (K) to degrees Celsius (°C) is °C = K - 273.15. Using this formula: °C = 398 - 273.15 = 124.85°C. When reporting the answer, it is common practice to maintain the precision of the original measurement. Since 398 K is given to the nearest whole number, the result is rounded to the nearest whole number, which is 125°C.

Question 53: What is the atomic number of an element?

The number of electrons in an atom's nucleus
The number of protons in an atom's nucleus (Correct answer)
The total number of protons and neutrons in an atom's nucleus
The number of neutrons in an atom's nucleus

Correct answer: The number of protons in an atom's nucleus

The atomic number (Z) is fundamentally defined by the number of protons found in an atom's nucleus. This unique count of protons determines the identity of an element and its position on the periodic table, distinguishing it from all other elements.

CART (Chemistry Acceleration Readiness Test) Exam

The CART is used at Miami Dade College to assess whether students can bypass CHM 1025 Introductory Chemistry. It covers high school and introductory college chemistry topics in 50 multiple-choice questions within 60 minutes.

Questions

60 min

Time Limit

50%

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