Question: Given the balanced equation representing a reaction: O₂→ O+O What occurs during this reaction?

Answer: 1) Energy is absorbed as bonds are brokenEXPLANATION: Whenever chemical bonds are broken energy is absorbed whenever chemical bonds are formed energy is released in this reaction the double bond of the diatomic oxygen molecule is been chemically broken producing two atoms of oxygen

Question: In terms of entropy and energy, systems in nature tend to undergo changes towards:

Answer: 3)Higher Entropy and lower energyEXPLANATION:Entropy is a measure of the disorder in the system. In nature, systems favor a state of greater randomness or disorder and hence a higher entropy. Also in nature, systems tend to go from a higher energy state to a lower energy state.

Question: Which term is defined as the difference between the potential energy of the products and the potential energy of the reactants in a chemical reaction?

Answer: 4) heat of reaction EXPLANATION: reactants involved in a chemical reaction will be at a specific potential energy measured in kilojoules after the reaction the products will be at a different potential energy level. The net difference between these two energy levels is referred to as the heat of reaction (∆H)

Question: What is the atomic number of the element whose atoms bond to each other in chains, rings, and networks.

Answer: 3)6 EXPLANATION: Carbon having the atomic number six has the ability to form bonds not only with other atoms but also indefinitely with each other. The hydrocarbon series shown in table Q consists of chains and carbon atoms. The organic molecule benzene (C₆H₆) has a ring structure. Diamond made from pure carbon is a network solid containing very strong covalent bonds

Question: How many pairs of electrons are shared between two adjacent Carbon atoms in a saturated hydrocarbon?

Answer: 1)1 EXPLANATION:In saturated hydrocarbons, carbon atoms are bonded to each other by single covalent bonds. A single covalent bond consists of one pair of shared electrons.

Question: Given the balanced equation representing a reaction:4Al(s)+3O₂(g)→2Al₂O₃As the aluminum loses 12 moles of electrons in the oxygen:

Answer: 2) Gains 12 moles of electrons,EXPLANATION: In all chemical reactions, the law of conservation of mass, charges and energy must be obeyed. Thus in any chemical reaction, the total number of atoms and the total mass of the reactants must be the same as that of the products and the charges on both sides of the balanced equation must also be equal. Therefore, in this balanced equation, the 12 electrons that are lost by the Al atoms are gained by the O atoms when forming the product 2Al₂O₃(s)

Question: Which compound is an electrolyte?1)CH₃CHO2)CH₃OCH₃3)CH₃COOH4)CH₃CH₂CH₃

Answer: 3)CH₃COOHEXPLANATION: A substance that conducts an electrical current when dissolved in water is called an electrolyte. Examples of some electrolytes are all ionic compounds (salts), acids, and bases. These substances will dissociate or ionize, producing electrolytes, Choice 3 is ethanolic acid as shown in table K, making it an electrolyte. Organic molecules, such as saturated hydrocarbon's, alcohol and alkynes contain covalent bonds that do not produce ions in solution and would not conduct an electric current.

Question: Which statement describes one acid-base theory?

Answer: 2)An acid is an H⁺ plus donor, and a base is an H⁺ acceptor EXPLANATION:The Bronsted-Lowry theory defines an acid as a substance that can donate a proton (H⁺) to another substance and defines a base as a substance that can except a proton (H⁺) from another substance

Question: Which compounds are classified as Arrhenius acids?1)HCl and NaOH2)HNO₃ and NaCl3)NH₃ and H₂CO₃4)HBr and H₂SO₄

Answer: 4)HBr and H₂SO₄EXPLANATION:By definition, an Arrhenius acid is a compound yielding hydrogen ions (H⁺) as the only ⁺ ions in an aqueous solution. These ions make the solution acidic. HBr and H₂SO₄ in an aqueous solution and are therefore classified as Arrhenius acids (see table K for H₂SO₄)

Question: Which statement describes the stability of the nuclei of potassium atoms?1) All potassium atoms have stable nuclei that spontaneously decay.2) All potassium atoms have unstable nuclei that do not spontaneously decay.3) Some potassium atoms have unstable nuclei that spontaneous decay.4) Some potassium atoms have unstable nuclei that do not spontaneously decay

Answer: 3) some potassium atoms have unstable nuclei that spontaneously decayEXPLANATION: potassium has many isotopes, of which, most but not all are stable, being non-radioactive. From table N, it shows two different radioisotopes of potassium ³⁷K and ⁴² K. In all radioactive atoms, the nucleus is unstable and emits particles and/or energy as it disintegrates to a more stable state

Question: In a redox reaction, which particles are lost and gained in equal numbers?

Answer: 1)electronsEXPLANATION:In redox reactions, oxidation and reduction occur simultaneously. In oxidation, there is a loss of electrons resulting in an increase in the oxidation number. In reduction, there is a gain of electrons resulting in a decrease in the oxidation number. In a redox reaction, the number of electrons lost equals the number of electrons gained. This conserves charges in the reaction.

Question: Which is the oxidation state for an Mn atom?

Answer: 1)0EXPLANATION: The oxidation state of an uncombined atom is 0, being neutral in nature. The selected oxidation states shown on the periodic table for any given element represents the charge of an atom of that element after gaining or losing electron(s), or the apparent charge resulting from an unequal sharing of electron(s) with another atom when undergoing a chemical reaction.

Question: Which compounds are classified as electrolytes?1)KNO₃ and H₂SO₄2)KNO₃ and CH₃OH3)CH₃OCH₃ and H₂SO₄ 4)CH₃OCH₃ and CH₃OH

Answer: 1)KNO₃ and H₂SO₄EXPLANATION: A substance that conducts an electrical current when dissolved in water is called an electrolyte. Examples of some electrolytes are all ionic compounds (salts), bases and acids. These substances will dissociate or ionize in an aqueous solution, producing a solution that conducts a current. Table K shows that H₂SO₄ is sulfuric acid, while KNO₃ is a salt.

Question: Which compound is an Arrhenius base?1)CO₂2)CaSO₄3)Ca(OH)₂4)C₂H₅OH

Answer: 3)Ca(OH)₂By definition, an Arrhenius base is a compound yielding hydroxide ions (OH-) as the only negative ion in an aqueous solution.

Question: According to one acid-base theory, a water molecule acts as a base when it accepts

Answer: 1) A H⁺ ion EXPLANATION: In the Bronsted-Lowry theory, a base is a substance that accepts protons from another substance. An example of this would be when a water molecule accepts H⁺ ions, forming a hydronium ion (see table E)

Question: Given the equation representing a system at equilibrium: which statement describes this reaction at equilibrium?1) The concentration of N₂ (g) decreases2) The concentration of N₂ (g) is constant3) The rate of the reverse reaction decreases.4)The rate of the reverse reaction increases

Answer: 1) The concentration of N₂(g) is constantEXPLANATION: When the chemical system is in equilibrium, the reaction rates in both directions, forward and reverse, are the same, and the concentrations of reactants and products are constant but not necessarily equal.

Question: The acidity or alkalinity of an unknown aqueous solution is indicated by its

Answer: 1) pH value EXPLANATION: The pH scale indicates the concentration of the hydrogen ions in a solution. Acidic solutions have a pH less than seven, and basic solutions have a pH higher than seven. The pH scale is a logarithmic scale. A decrease of one on the pH scale represents a 10-fold increase in the H+ ion concentration

Question: The laboratory process in which the volume of a solution of known concentration is used to determine the concentration of another's solution is called

Answer: 3) Titration EXPLANATION: Titration is a process used to determine the concentration (molarity) of an acid or base by slowly combining it with a base or acid, respectively, of known concentration called a standard. An indicator is normally used to determine the endpoint in an acid-base titration.

Question: Which list of nuclear emissions is arranged in order from the greatest penetrating power to the least penetrating power?1) alpha particle, beta particle, gamma ray2) alpha particle, gamma ray, beta particle 3)gamma ray, alpha particle, beta particle4)gamma ray, beta particle, alpha particle

Answer: 4) gamma ray, beta particle, alpha particleEXPLANATION:The penetrating power of nuclear emissions is related to their size and energy. The larger the emission, the lower the penetrating power. open to table O. Gamma radiation is only pure energy having no mass or charge, this lack of mass and charge is represented by the zeros in front of the gamma symbol

Question: 1)FissionEXPLANATION:Fission is the splitting of an atomic nucleus into two or more lighter nuclei.

Answer: Given the diagram representing a reaction: what type of change is represented?

Question: Which element has atoms that can bond with each other to form ring, chain, and network structures?

Answer: 3) carbon EXPLANATION: carbon has the ability to form bonds not only with other atoms but also indefinitely with other carbon atoms. The hydrocarbon series shown in the structural formula column in table Q consists of chains of carbon atoms. The organic molecule benzene (C₆H₆) has a ring structure shape. Diamond, made from pure carbon, is a network solid containing very strong covalent bonds

Question: What is the number of electrons shared in the multiple carbon-carbon bond in one molecule of 1-pentyne?

Answer: 1) 6EXPLANATION: Open to table Q-homologous series of hydrocarbons. Pentyne, having the suffix-YNE is a member of the alkynes. In the structural formula column, it shows that alkynes contain a triple covalent bond. Each covalent bond between two carbon atoms share a pair of electrons. Therefore in a triple bond, a total of 6 electrons are being shared

Question: Butanol, butanone, and diethylether have different properties because the molecules of each compound differ in their

Answer: 3) types of functional groups EXPLANATION: Open to table or-organic functional groups. The functional group is a particular arrangement of atoms, which gives characteristic properties to an organic molecule. Butanal having a suffix of -AL, is a member of the aldehydes. Butanone, having a suffix of -ONE, is a member of the ketones. Diethylether is an ether. These three substances, having different functional groups, would exhibit different properties

Question: What occurs when a magnesium atom becomes a magnesium ion?

Answer: 3) electrons are lost in the oxidation number increasesEXPLANATION: magnesium, being a metal, loses electrons in chemical reactions. The loss of electrons (oxidation) causes an increase in the oxidation state of the particle. Mg⁰ will lose its two valence electrons becoming Mg²⁺

Question: Energy is required to produce a chemical change during

Answer: 2) electrolysis EXPLANATION:electrolysis is a process in which an electrical current is used to cause a chemical change. The other choices are physical changes

Question: The reaction of an Arrhenius acid with an Arrhenius base produces water and

Answer: 1) a salt EXPLANATION: when solutions of an acid and a base are mixed, the pH heads towards neutralization, producing a water and salt

Question: One acid-base theory defines an acid as an

Answer: 4) H⁺ donorEXPLANATION: In the Bronsted-Lowry theory, and acid is a substance that donates a proton (H⁺) to another substance

Question: Which phrase describes the decay modes and the half-lives of K-37 and K-42?

Answer: 3) different decay modes and different half-lives EXPLANATION: Open to table N-selected radioisotopes and locate these potassium radioisotopes. K-37 undergoes β⁺,positive beta decay, which is the emission of a positive electron or a positron. K-42 undergoes β⁻, negative beta decay, which is the emission of an ordinary electron. As shown, the half-lives of these radioisotopes are different

Question: Which particle has a mass that is approximately equal to the mass of a proton?

Answer: 3) a neutron EXPLANATION:The nucleus consists of two subatomic particles, protons and neutrons. Both of these particles have a proximately the same mass, being equal to one atomic mass unit (u)

Question: Which change occurs during a nuclear fission reaction?

Answer: 4) matter is converted to energy EXPLANATION: nuclear fission is a nuclear reaction in which the nucleus of an atom is split into smaller nuclei. In all nuclear reactions, matter is converted to energy. Nuclear reactions release tremendous amounts of energy according to Einstein's equation, E=mc²

Question: In which 1.0-gram sample are the particles arranged in a crystal structure?

Answer: 1) CaCl₂EXPLANATION: A crystal lattice structure can exist only in a solid

Question: When a reversible reaction is at equilibrium, the concentration of products and the concentration of reactants must be

Answer: 3) Constant EXPLANATION: when a chemical system is in equilibrium, the reaction rates in both directions, forward and reverse, are the same and the concentrations of the reactants and products are constant, but not necessarily equal

Question: In chemical reactions, the difference between the potential energy of the products and the potential energy of the reactants is equal to the

Answer: 3) heat of reaction EXPLANATION: The reactants involved in a chemical reaction will be at a specific potential energy. After the reaction, the products will be at a different potential energy. By definition, the difference between the potential energy of the products and that of the reactance is the heat of reaction (∆H)

Question: What occurs when a catalyst is added to a chemical reaction?

Answer: 1) an alternate reaction pathway with a lower activation energy EXPLANATION: A catalyst is a substance that increases the speed which a reaction takes place or equilibrium is reached. The catalyst accomplishes this by lowering the activation energy needed for the forward and reverse reaction. In the graph, the solid line represents the change in potential energy that occurs during the given reaction: A+B->C. The dotted line represents the pathway of the same reaction when a catalyst is added. Notice that a different reaction pathway occurs with the peak of the potential energy graph (the top of the curve) being lowered. Thus the activation energy is decreased, without changing the positions of the potential energy of the plateaus (reactants and products).

Question: What is the name of the compound with the formula CH₃CH₂CH₂NH₂

Answer: 2) 1-propanamineEXPLANATION: this is an organic compound and can be identified by its functional group given in table R. In this table locate the amine compounds. These compounds contain the functional group of -N-and all amine compounds names and with -INE. Also, in the example column for amine is the same compound (with its name) as the compound in the question

Question: Which compound is an isomer of C₂H₅OC₂H₅

Answer: 4)C₄H₉OHEXPLANATION:An isomer of this compound would have the same molecular formula but a different structural formula. In the molecular formula of the given compound and that of choice 4, both contain 4 C atoms, 10 H atoms, and 1 O atom. Being an isomer, it would exhibit different physical and chemical properties compared to the given compound

Question: Ethanoic acid and 1-butanol can react to produce water and a compound classified as an

Answer: 3) Ester EXPLANATION: In table R, it shows that alcohols have the suffix of -OL, thus 1-butanol is an alcohol. Esterification is the reaction between an acid and an alcohol to produce an ester and water. Organic esters are characterized by a pleasant taste and fragrance

Question: During an oxidation-reduction reaction, the number of electrons gained is

Answer: 1) equal to the number of electrons lost EXPLANATION: In redox reactions, oxidation and reduction occur simultaneously. In oxidation there is a loss of electrons resulting in an increase in the oxidation number. In reduction there is a gain of electrons resulting in a decrease in the oxidation number. The number of electrons lost and gained in a redox reaction is always the same

Question: Which process requires energy for a non-spontaneous redox reaction to occur?

Answer: 2) electrolysis EXPLANATION: In electrolysis of water, a direct current (DC) is needed to chemically decompose water into oxygen and hydrogen gas. Electrolysis occurs in an electrolytic cell, where an electric current, such as a battery, is needed to cause and sustain a non-spontaneous reaction

Question: Which pair of compounds represents one Arrhenius acid and one Arrhenius base?

Answer: 3) HNO₃ and NaOHEXPLANATION: An Arrhenius acid is a compound yielding hydrogen ions, H⁺, as the only positive ion in an aqueous solution. An Arrhenius base is a compound yielding hydroxide ions (OH⁻) as the only negative ion in an aqueous solution. Table K-common acids, shows that HNO₃ is nitric acid and is classified as an Arrhenius acid. From table L, NaOH is sodium hydroxide, an Arrhenius base. In choice 1, CH₃OH is methanol, containing the functional group -OH (see table R)