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The results of the gold foil experiment led to the conclusion that an atom is*
Atoms are neutral because the number of*
In the ground state, valence electrons of a krypton atom are found in*
According to the wave-mechanical model of the atom, electrons are located in*
Which electron configuration represents the electrons in an atom of sodium in the ground state at STP?*
The elements on the Periodic Table of the Elements are arranged in order of increasing*
Which element is malleable at STP?*
At 298 K and 1 atm, which noble gas has the lowest density?*
Which two terms represent types of chemical formulas?*
Which quantities are conserved in all chemical reactions?*
Which term represents the sum of the atomic masses of the atoms in a molecule?*
Which equation represents energy being absorbed as a bond is broken?*
Which term is used to describe the attraction that an oxygen atom has for the electrons in a chemical bond?*
Which substance can not be decomposed by chemical means?*
A beaker contains a dilute sodium chloride solution at 1 atmosphere. What happens to the number of solute particles in the solution and the boiling point of the solution, as more sodium chloride is dissolved?*
Which form of energy is transferred when an ice cube at 0°C is placed in a beaker of water at 50°C?*
The average kinetic energy of the particles in a sample of matter is expressed as*
At STP, which gas sample has the same number of molecules as 2.0 liters of CH4(g) at STP?*
Given the equation:
I2(s) → I2(g)
Which phrase describes this change?*
Which term identifies a factor that will shift a chemical equilibrium?*
According to which theory or law is a chemical reaction most likely to occur when two particles with the proper energy and orientation interact with each other?*
Addition of a catalyst can speed up a reaction by providing an alternate reaction pathway that has a*
Which compound is saturated?*
An alcohol and an ether have the same molecular formula, C2H6O. These two compounds have*
Which metal is most easily oxidized?*
Which substance is an Arrhenius acid?*
Which statement describes an electrolyte?*
Which type of reaction occurs when an Arrhenius acid reacts with an Arrhenius base to form a salt and water?*
Compared to the energy released per mole of reactant during chemical reactions, the energy released per mole of reactant during nuclear reactions is*
Which phrase describes a risk of using the radioisotope Co-60 in treating cancer?*
The three nuclides, U-233, U-235, and U-238, are isotopes of uranium because they have the same number of protons per atom and*
Given the information in the table below:
Diamond and graphite have different properties because they have different*
Given the equation representing a chemical reaction:
NaCl(aq) + AgNO3(aq) → NaNO3(aq) + AgCl(s)
This reaction is classified as a*
What is the formula for iron(II) oxide?*
Given the reaction:
2KClO3(s) → 2KCl(s) + 3O2(g)
How many moles of KClO3 must completely react to produce 6 moles of O2?*
What is the number of moles of CO2 in a 220.-gram sample of CO2 (gram-formula mass = 44 g/mol)?*
A solution contains 25 grams of KNO3 dissolved in 200. grams of H2O. Which numerical setup can be used to calculate the percent by mass of KNO3 in this solution?*
What is the molarity of 0.50 liter of an aqueous solution that contains 0.20 mole of NaOH (gram-formula mass = 40. g/mol)?*
A mixture consists of ethanol and water. Some properties of ethanol and water are given in the table below.
Which statement describes a property of ethanol after being separated from the mixture?*
A rigid cylinder with a movable piston contains a sample of hydrogen gas. At 330. K, this sample has a pressure of 150. kPa and a volume of 3.50 L. What is the volume of this sample at STP?*
Which numerical setup can be used to calculate the heat energy required to completely melt 100. grams of H2O(s) at 0°C?*
During which phase change does the entropy of a sample of H2O increase?*
Given the formula for a compound:
What is a chemical name for this compound?*
Given the equation for a reaction:
C4H10 + Cl2 → C4H9Cl + HCl
Which type of reaction is represented by the equation?*
Which half-reaction equation represents reduction?*
Given the balanced ionic equation representing a reaction:
Zn(s) + Co2+(aq) → Zn2+(aq) + Co(s)
Which statement describes the electrons involved in this reaction?*
What are the two oxidation states of nitrogen in NH4NO2?*
The table below shows the molar concentrations of hydronium ion, H3O+, in four different solutions.
Which solution has the highest pH?*
Which type of nuclear reaction is represented by the equation?*
Which nuclear emission has the least penetrating power and the greatest ionizing ability?*
Base your answers to questions 51 through 54 on the information below and on your knowledge of chemistry.
The formulas and names of four chloride compounds are shown in the table below.
Identify the noble gas that has atoms with the same electron configuration as the metal ions in rubidium chloride, when both the atoms and the ions are in the ground state.*
Explain, in terms of atomic structure, why the radius of a cesium ion in cesium chloride is smaller than the radius of a cesium atom when both are in the ground state.*
In the space in your answer booklet, draw a Lewis electron-dot diagram for a molecule of HCl.*
Explain, in terms of charge distribution, why a molecule of carbon tetrachloride is a nonpolar molecule.*
Base your answers to questions 55 through 57 on the information below and on your knowledge of chemistry.
Some isotopes of neon are Ne-19, Ne-20, Ne-21, Ne-22, and Ne-24. The neon-24 decays by beta emission. The atomic mass and natural abundance for the naturally occurring isotopes of neon are shown in the table below.
Identify the decay mode of Ne-19.*
State the number of neutrons in an atom of Ne-20 and the number of neutrons in an atom of Ne-22.*
Show a numerical setup for calculating the atomic mass of neon.*
Base your answers to questions 58 through 60 on the information below and on your knowledge of chemistry.
Periodic trends are observed in the properties of the elements in Period 3 on the Periodic Table. These elements vary in physical properties, such as phase, and in chemical properties, such as their ability to lose or gain electrons during a chemical reaction.
Identify the metals in Period 3 on the Periodic Table.*
Identify the element in Period 3 that requires the least amount of energy to remove the most loosely held electrons from a mole of gaseous atoms of the element in the ground state.*
State the general trend in atomic radius as the elements in Period 3 are considered in order of increasing atomic number.*
Base your answers to questions 61 through 63 on the information below and on your knowledge of chemistry.
A thiol is very similar to an alcohol, but a thiol has a sulfur atom instead of an oxygen atom in the functional group. The equation below represents a reaction of methanethiol and iodine, producing dimethyl disulfide and hydrogen iodide.
State the number of electrons shared between the sulfur atoms in the dimethyl disulfide.*
Identify the polarity of an H–I bond and the polarity of an S–S bond.*
Explain, in terms of electron configuration, why sulfur atoms and oxygen atoms form compounds with similar molecular structures.*
Base your answers to questions 64 and 65 on the information below and on your knowledge of chemistry.
A student constructs an electrochemical cell. A diagram of the operating cell and the unbalanced ionic equation representing the reaction occurring in the cell are shown below.
The blue color of the solution in the copper half-cell indicates the presence of Cu2+ ions. The student observes that the blue color becomes less intense as the cell operates.
Identify the type of electrochemical cell represented by the diagram.*
State one inference that the student can make about the concentration of the Cu2+ ions based on the change in intensity of the color of the Cu(NO3)2(aq) solution as the cell operates.*
Base your answers to questions 66 through 69 on the information below and on your knowledge of chemistry.
In a laboratory investigation, a student is given a sample that is a mixture of 3.0 grams of NaCl(s) and 4.0 grams of sand, which is mostly SiO2(s). The purpose of the investigation is to separate and recover the compounds in the sample. In the first step, the student places the sample in a 250-mL flask. Then, 50. grams of distilled water are added to the flask, and the contents are thoroughly stirred. The mixture in the flask is then filtered, using the equipment represented by the diagram below.
Explain, in terms of solubility, why the mixture in the flask remains heterogeneous even after thorough stirring.*
Based on Table G, state evidence that all of the NaCl(s) in the flask would dissolve in the distilled water at 20.°C.*
Describe a procedure to remove the water from the mixture that passes through the filter and collects in the beaker.*
The student reports that 3.4 grams of NaCl(s) were recovered from the mixture. Show a numerical setup for calculating the student’s percent error.*
Base your answers to questions 70 through 73 on the information below and on your knowledge of chemistry.
In a laboratory activity, the volume of helium gas in a rigid cylinder with a movable piston is varied by changing the temperature of the gas. The activity is done at a constant pressure of 100. kPa. Data from the activity are plotted on the graph below.
Determine the temperature of the He(g) at a volume of 15.0 mL.*
Explain, in terms of particle volume, why the sample of helium can not be compressed by the piston to zero volume.*
State what happens to the average distance between the He atoms as the gas is heated.*
State a change in pressure that will cause the helium in the cylinder to behave more like an ideal gas.*
Base your answers to questions 74 through 76 on the information below and on your knowledge of chemistry.
The balanced equation below represents the reaction between a 5.0-gram sample of zinc metal and a 0.5 M solution of hydrochloric acid. The reaction takes place in an open test tube at 298 K and 1 atm in a laboratory activity.
Zn(s) + 2HCl(aq) → H2(g) + ZnCl2(aq) + energy
State one change in reaction conditions, other than adding a catalyst, that will increase the rate of the reaction.*
On the labeled axes in your answer booklet, draw a potential energy diagram for this reaction.*
Explain why this reaction will not reach equilibrium.*
Base your answers to questions 77 through 79 on the information below and on your knowledge of chemistry.
Crude oil, primarily a mixture of hydrocarbons, is separated into useful components in a fractionating tower. At the bottom of the tower, the crude oil is heated to about 400°C. The gases formed rise and cool. Most of the gases condense and are collected as liquid fractions. The table below shows the temperature ranges for collecting various hydrocarbon fractions.
Determine the number of carbon atoms in one molecule of an alkane that has 22 hydrogen atoms in the molecule.*
State the temperature range for the fraction collected that contains octane molecules.*
Draw a structural formula for 3-ethylhexane.*
Base your answers to questions 80 through 82 on the information below and on your knowledge of chemistry.
In a laboratory activity, a student titrates a 20.0-milliliter sample of HCl(aq) using 0.025 M NaOH(aq). In one of the titration trials, 17.6 milliliters of the base solution exactly neutralizes the acid sample.
Identify the positive ion in the sample of HCl(aq).*
Show a numerical setup for calculating the concentration of the hydrochloric acid using the titration data.*
The concentration of the base is expressed to what number of significant figures?*
Base your answers to questions 83 through 85 on the information below and on your knowledge of chemistry.
In the past, some paints that glowed in the dark contained zinc sulfide and salts of Ra-226. As the radioisotope Ra-226 decayed, the energy released caused the zinc sulfide in these paints to emit light. The half-lives for Ra-226 and two other radioisotopes used in these paints are listed on the table below.
Explain, in terms of half-lives, why Ra-226 may have been used more often than the other isotopes in these paints.*
Complete the nuclear equation below for the beta decay of Pm-147 by writing an isotopic notation for the missing product.
What fraction of an original Ra-228 sample remains unchanged after 17.4 years?*