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Which change occurs when an atom in an excited state returns to the ground state?*
The valence electrons in an atom of phosphorus in the ground state are all found in*
Which two elements have the most similar chemical properties?*
Which phrase describes a compound that consists of two elements?*
The formula mass of a compound is the*
The arrangement of the elements from left to right in Period 4 on the Periodic Table is based on*
Which diatomic molecule is formed when the two atoms share six electrons?*
Which formula represents a polar molecule?*
Which element is least likely to undergo a chemical reaction?*
Which element has a melting point higher than the melting point of rhenium?*
Which property can be defined as the ability of a substance to be hammered into thin sheets?*
Which list of elements consists of a metal, a metalloid, and a noble gas?*
Which sample of matter has a crystal structure?*
One mole of liquid water and one mole of solid water have different*
Which substance can not be broken down by a chemical change?*
Which statement describes particles of an ideal gas, based on the kinetic molecular theory?*
Which expression could represent the concentration of a solution?*
Which form of energy is associated with the random motion of the particles in a sample of water?*
Which change is most likely to occur when a molecule of H2 and a molecule of I2 collide with proper orientation and sufficient energy?*
Which changes can reach dynamic equilibrium?*
What occurs when a reaction reaches equilibrium?*
In terms of potential energy, PE, which expression defines the heat of reaction for a chemical change?*
Systems in nature tend to undergo changes that result in*
What occurs when Cr3+ ions are reduced to Cr2+ ions?*
Where do reduction and oxidation occur in an electrolytic cell?*
Which compound is an electrolyte?*
When the hydronium ion concentration of an aqueous solution is increased by a factor of 10, the pH value of the solution*
The stability of isotopes is related to the ratio of which particles in the atoms?*
Which radioisotope has the fastest rate of decay?*
The atomic mass of an element is the weighted average of the atomic masses of*
Which list of elements is arranged in order of increasing electronegativity?*
The table below gives the masses of two different subatomic particles found in an atom.
Which of the subatomic particles are each paired with their corresponding name?*
Which electron configuration represents an excited state for an atom of calcium?*
At STP, graphite and diamond are two solid forms of carbon. Which statement explains why these two forms of carbon differ in hardness?*
Which equation shows conservation of charge?*
What occurs when potassium reacts with chlorine to form potassium chloride?*
Given the balanced equation representing a reaction:
H2 + energy → H + H
What occurs as bonds are broken in one mole of H2 molecules during this reaction?*
Which pair of atoms has the most polar bond?*
Which two notations represent isotopes of the same element?*
The graph below shows the volume and the mass of four different substances at STP.
Which of the four substances has the lowest density?*
What is the total amount of heat required to completely melt 347 grams of ice at its melting point?*
As the temperature of a reaction increases, it is expected that the reacting particles collide*
Given the formula representing a compound:
What is an IUPAC name for this compound?*
A voltaic cell converts chemical energy to*
Which acid and base react to form water and sodium sulfate?*
Given the equation representing a reaction:
H2CO3 + NH3 → NH4+ + HCO3−
According to one acid-base theory, the compound NH3 acts as a base because it*
Which statement describes characteristics of a 0.01 M KOH(aq) solution?*
Four statements about the development of the atomic model are shown below.
Which order of statements represents the historical development of the atomic model?*
Five cubes of iron are tested in a laboratory. The tests and the results are shown in the table below.
Which tests demonstrate chemical properties?*
What is the empirical formula for C6H12?*
Using Table G, determine the minimum mass of NaCl that must be dissolved in 200. grams of water to produce a saturated solution at 90.°C.*
State the physical property that makes it possible to separate a solution by distillation.*
Base your answers to questions 53 and 54 on the information below and on your knowledge of chemistry.
A beaker contains a liquid sample of a molecular substance. Both the beaker and the liquid are at 194 K. The graph below represents the relationship between temperature and time as the beaker and its contents are cooled for 12 minutes in a refrigerated chamber.
State what happens to the average kinetic energy of the molecules in the sample during the first 3 minutes.*
Identify the physical change occurring during the time interval, minute 4 to minute 9.*
Base your answers to questions 55 through 58 on the information below and on your knowledge of chemistry.
The equation below represents a reaction between propene and hydrogen bromide.
Cyclopropane, an isomer of propene, has a boiling point of –33ºC at standard pressure and is represented by the formula below.
Explain why this reaction can be classified as a synthesis reaction.*
Identify the class of organic compounds to which the product of this reaction belongs.*
Explain, in terms of molecular formulas and structural formulas, why cyclopropane is an isomer of propene.*
Convert the boiling point of cyclopropane at standard pressure to kelvins.*
Base your answers to questions 59 through 62 on the information below and on your knowledge of chemistry.
The radius of a lithium atom is 130. picometers, and the radius of a fluorine atom is 60. picometers. The radius of a lithium ion, Li+, is 59 picometers, and the radius of a fluoride ion, F−, is 133 picometers.
Compare the radius of a fluoride ion to the radius of a fluorine atom.*
Explain, in terms of subatomic particles, why the radius of a lithium ion is smaller than the radius of a lithium atom.*
Draw a Lewis electron-dot diagram for a fluoride ion.*
Describe the general trend in atomic radius as each element in Period 2 is considered in order from left to right.*
Base your answers to questions 63 and 64 on the information below and on your knowledge of chemistry.
Nuclear fission reactions can produce different radioisotopes. One of these radioisotopes is Te-137, which has a half-life of 2.5 seconds. The diagram below represents one of the many nuclear fission reactions.
State evidence that this nuclear reaction represents transmutation.*
Complete the nuclear equation below for the beta decay of Zr-97, by writing an isotopic notation for the missing product.
Base your answers to questions 65 through 68 on the information below and on your knowledge of chemistry.
Stamping an identification number into the steel frame of a bicycle compresses the crystal structure of the metal. If the number is filed off, there are scientific ways to reveal the number.
One method is to apply aqueous copper(II) chloride to the number area. The Cu2+ ions react with some iron atoms in the steel frame, producing copper atoms that show the pattern of the number. The ionic equation below represents this reaction.
Fe(s) + Cu2+(aq) → Fe2+(aq) + Cu(s)
Another method is to apply hydrochloric acid to the number area. The acid reacts with the iron, producing bubbles of hydrogen gas. The bubbles form faster where the metal was compressed, so the number becomes visible. The equation below represents this reaction.
2HCl(aq) + Fe(s) → FeCl2(aq) + H2(g)
Explain why the Fe atoms in the bicycle frame react with the Cu2+ ions.*
Determine the number of moles of hydrogen gas produced when 0.001 mole of HCl(aq) reacts completely with the iron metal.*
Write a balanced half-reaction equation for the reduction of the hydrogen ions to hydrogen gas.*
Describe one change in the HCl(aq) that will increase the rate at which hydrogen bubbles are produced when the acid is applied to the steel frame.*
Base your answers to questions 69 through 72 on the information below and on your knowledge of chemistry.
In an investigation, aqueous solutions are prepared by completely dissolving a different amount of NaCl(s) in each of four beakers containing 100.00 grams of H2O(ℓ) at room temperature. Each solution is heated and the temperature at which boiling occurred is measured. The data are recorded in the table below.
Identify the solute and the solvent used in this investigation.*
Show a numerical setup for calculating the percent by mass of NaCl in the solution in beaker 4.*
Explain, in terms of ions, why the ability to conduct an electric current is greater for the solution in beaker 4 than for the solution in beaker 1.*
State the relationship between the concentration of ions and the boiling point for these solutions.*
Base your answers to questions 73 through 75 on the information below and on your knowledge of chemistry.
One type of voltaic cell, called a mercury battery, uses zinc and mercury(II) oxide to generate an electric current. Mercury batteries were used because of their miniature size, even though mercury is toxic. The overall reaction for a mercury battery is given in the equation below.
Zn(s) + HgO(s) → ZnO(s) + Hg(ℓ)
Determine the change in the oxidation number of zinc during the operation of the cell.*
Compare the number of moles of electrons lost to the number of moles of electrons gained during the reaction.*
Using information in the passage, state one risk and one benefit of using a mercury battery.*
Base your answers to questions 76 through 79 on the information below and on your knowledge of chemistry.
A company produces a colorless vinegar that is 5.0% HC2H3O2 in water. Using thymol blue as an indicator, a student titrates a 15.0-milliliter sample of the vinegar with 43.1 milliliters of a 0.30 M NaOH(aq) solution until the acid is neutralized.
Based on Table M, what is the color of the indicator in the vinegar solution before any base is added?*
Identify the negative ion in the NaOH(aq) used in this titration.*
The concentration of the base used in this titration is expressed to what number of significant figures?*
Determine the molarity of the HC2H3O2 in the vinegar sample, using the titration data.*
Base your answers to questions 80 through 84 on the information below and on your knowledge of chemistry.
In industry, ethanol is primarily produced by two different reactions. One process involves the reaction of glucose in the presence of an enzyme that acts as a catalyst. The equation below represents this reaction.
In another reaction, ethanol is produced from ethene and water. The equation below represents this reaction in which H2SO4 is a catalyst.
Industrial ethanol can be oxidized using a catalyst to produce ethanal. The equation representing this oxidation is shown below.
Identify the element that causes the reactant in equation 1 to be classified as an organic compound.*
Identify the type of organic reaction represented by equation 1.*
Explain why the hydrocarbon in equation 2 is unsaturated.*
Explain, in terms of intermolecular forces, why ethanol has a much higher boiling point than ethene, at standard pressure.*
Draw a structural formula for the organic product in equation 3.*
A rigid cylinder with a movable piston contains a sample of helium gas. The temperature of the gas is held constant as the piston is pulled outward. Which graph represents the relationship between the volume of the gas and the pressure of the gas?*