Holt Chemistry Standards Assessment Answers

7. Why is a solution of sugar in water not a good electrical conductor? a. Sugar does not form ions in solution b. The ionic bonds of sugar molecules are too strong to carry a current c. Not enough sugar dissolves for the solution to become a conductor. d. A solution of sugar in water is not very conductive because it is mostly water, which is not very conductive.

a. Sugar does not form ions in solution

As a covalent compound melts, heat energy is added and enthalpy increases, but the temperature does not change. What is the effect on the molecules of the added energy?

The energy causes the molecules to move farther apart as intermolecular attractions are broken

Based on changes in entropy and enthalpy, predict whether this reaction is spontaneous or nonspontaneous: 2AB(s) ---> A2(g) + B2(g) + 799 kJ

∆G is negative and the reaction is spontaneous.

Antimony has 2 isotopes. One, amounting to 57.3% of the atoms, has a mass of 120.9 amu. The other, 42.7% of the atoms, has a mass of 122.9 amu. What's the avg atomic mass of antimony? A. 120.9 amu B. 121.8 amu C. 121.9 amu D. 122.1 amu

B. 121.8 amu

How many moles of calcium (mass=40.1) are in a serving of milk containing 290mg of calcium? A. 2.90 X 10 to the -3rd power B. 7.23 X 10 to the -3 power C. 2.90 mol D. 7.23 mol

B. 7.23 X 10 to the -3 power

What observation about electrons, made by de Broglie, supported quantum theory and the Bohr model of the atom? A. Electrons behave as particles and have mass B. Beams of electrons diffract as if they were waves C. Most of the volume of an atom is an electron cloud D. A beam of electrons is deflected by a charged plate

B. Beams of electrons diffract as if they were waves

Which of these thermodynamic values can be determined using an adiabatic calorimeter? A. Delta G B. Delta H C. Delta S D. Delta T

B. Delta H

Which of these is a transition element? A.Ba B. Fe C. C D. Xe

B. Fe

Why do scientists need models as opposed to directly observing electrons? A. Models can be changed. B. There is no technology that allows direct observation of electrons. C. The charges on the electrons and protons interfere with direct observation of the atom. D. Scientists cannot measure the speed of electrons with sufficient accuracy to determine which model is correct.

B. There is no technology that allows direct observation of electrons.

Element A has two isotopes. One has an atomic mass of 120 and constitutes 60%; the other has an atomic mass of 122 and constitutes 40%. Which range below includes the average atomic mass of Element A? A. Less than 120 B. between 120 and 121 C. between 121 and 122 D. greater than 122

B. between B. between 120 and 121120 and 121

If the reaction that fills the air bag is the decomposition of sodium azide, represented by the equation, 2NaN3(s) --> 2Na(s) + 3N2(g), how many moles of products are produced by the decomposition of 3.0 moles of sodium azide? A. 5 moles B.7.5 moles C. 10 moles D. 12.5 moles

B.7.5 moles

When an electric current is passed through water, hydrogen and oxygen are produced in 2:1 volume ratio and a 1:8 mass ratio. What is the empirical formula of water? A.HO B.H2O C.H2O8 D.HO8

B.H2O

How many ions are in 0.5 mole of NaCl? A. 1.204 X 10 to the 23rd power B. 3.011 X 10 to the 23rd power C. 6.022 X 10 to the 23rd power D. 9.033 X 10 to the 23rd power

C. 6.022 X 10 to the 23rd power

Which of the following statements about compounds is true? A. Each compound contains only one element B.Compounds can be classified as either heterogeneous or homogeneous. C. A compound has defined ratio by mass of the elements that it contains D. Compounds vary in chemical composition depending on the sample size

C. A compound has defined ratio by mass of the elements that it contains

Why is the boiling point of ammonia, NH3 130*C higher than that of methane, CH4? A. Carbon forms covalent bonds, whereas nitrogen forms ionic bonds B. Carbon forms ionic bonds, whereas nitrogen forms covalent bonds C. Ammonia has polar molecules because of an unshared pair of electrons. D. Methane has polar molecules because of an unshared pair of electrons.

C. Ammonia has polar molecules because of an unshared pair of electrons.

Which of the following elements is formed in stars? A. curium C. gold B. einsteinium D. mendelevium

C. Gold

The model of the atom has changed over time because A. earlier models were proven wrong B. elecrons do not revolve around the nucleus C. as new properties of atoms were discovered, models had to be revised to account for those properties D. new particles were discovered, so the model had to be changed to explain how they could exist

C. as new properties of atoms were discovered, models had to be revised to account for those properties

Which of the following is a characteristic of a salt? A. bends but does not shatter when struck sharply B. has the ability to conduct electric current in the solid state C. has the ability to conduct electric current in the liquid state D. melts at temperatures that are slightly higher than room temperature

C. has the ability to conduct electric current in the liquid state

Which of the following is a property of noble gases as a result of their stable electron configuration? A. large atomic radii B. high electron affinities C. high ionization energies D. a tendency to form both cations and anions

C. high ionization energies

How does the energy required to produce glucose from carbon dioxide in a high temperature industrial process compare to the energy required to produce glucose by photosynthesis? A. less energy input required B. more energy input required C. identical energy input required D. need more information

C. identical energy input required

Which of the following determines the temperature of a substance? A. charge on ions B. color C. motion of particles D. total mass of materials

C. motion of particles

Which of the following can be determined from the epirical formula of a compound alone? A. The true formula of the compound B. Molecular mass of the compound C. percentage composition of the compound D. arrangement of atoms within a molecule of the compound

C. percentage composition of the compound

A mole is defined as A. the amount of mass in exactly 1.00 mL B. the number of atoms in 12 grams of any element C. the number of atoms in 12 grams of carbon-12 D. a dozen dozens

C. the number of atoms in 12 grams of carbon-12

(Chart Diagram)What is the specific heat of aluminum chloride, which has a molar mass of 133.4? A.-1.45 J/K•g B.-0.69 J/K•g C.0.69 J/K•g D.1.45 J/K•g

C.0.69 J/K•g

Which of the following forms the strongest hydrogen bonds? A.CH4 B.C2H6 C.H2O D.H2Se

C.H2O

Which of the following is an element? A. BaCl2 B.CO C.He D.NaOH

C.He

The energy produced by the explosion is heat. How does the production of large amounts of heat cause the effects observed in an explosion? A.The products of the reaction burn. B.The products of the reaction condense, releasing the heat energy. C.Heat makes the gaseous reaction products move and expand very rapidly. D.Heat causes the atoms to ionize and the ions that are produced by this reaction cause the effects of the explosion.

C.Heat makes the gaseous reaction products move and expand very rapidly.

Which of the following pairs of conditions will favor a spontaneous reaction? A.a decrease in entropy and a decrease in enthalpy B.a decrease in entropy and an increase in enthalpy C.an increase in entropy and a decrease in enthalpy D.an increase in entropy and an increase in enthalpy

C.an increase in entropy and a decrease in enthalpy

According to VSEPR theory, which of these is caused by repulsion between electron pairs surrounding an atom? A. Breaking of a chemical bond B. Formation of a sea of electrons C. formation of a covalent chemical bond D. separation of electron pairs as much as possible

D. separation of electron pairs as much as possible

What effect does carbon dioxide have on a fire? A. changes the mole ratio of the reactants B. decreases the actual yield of the reaction C. decreases the potential yield of the reaction D. slows the reaction by limiting the reactant oxygen

D. slows the reaction by limiting the reactant oxygen

Which of the following is the correct Lewis dot structure for aluminum, which has an atomic number of 13? A :A ̇l: B ∙Al ̈∙ * C. ∙Al ̇∙ D. ∙Al ̈

D. ∙Al ̈

The phase change from liquid to solid releases 6.01 kilojoules of energy for each mole of water.How much heat energy is provided to a tree branch by the formation of 36 grams of ice? A.-12.02 kJ B.-6.01 kJ C.6.01 kJ D.12.02 kJ

D.12.02 kJ

Which of the following has the greatest force between particles? A.Cl2 B.HCl C.HOCl D.NaCl

D.NaCl

How would the experimental result have been different if hydrogen gas existed as individual atoms whereas oxygen formed molecules with 2 atoms bound by a covalent bond? A.Result would be the same. B.Volume ratio of hydrogen to oxygen would be 1:1 C.Volume ratio of hydrogen to oxygen would be 1:4 D.Volume ratio of hydrogen to oxygen would be 4:1

D.Volume ratio of hydrogen to oxygen would be 4:1

What is the theoretical yield of nitrogen if 1.0 moles of nitroglycerin is detonated? F.21.0 grams G.28.0 grams H.42.0 grams I.168.0 grams

F. 21.0 grams

Which of the following pairs of elements are most likely to form an ionic bond? F. Br and Ca H. Ca and Mg G. Br and N I. Ca and Fe

F. Br and Ca

Write a balanced equation for this reaction: iron(III) nitrate + lithium hydroxide lithium nitrate + iron(III) hydroxide

Fe(NO3)3 + 3LiOH 3LiNO3 + Fe(OH)3

Which of these processes is an endothermic physical change? F. an explosion G. melting of butter H. condensation of a gas I. formation of a solid when two liquids are mixed

G. melting of butter

Based on the nature of the reactants and products, what can be deduced about the entropy change during photosynthesis? F.Entropy increases because one of the products is an element. G.Entropy decreases because there are substantially fewer molecules of product than of reactants. H.Entropy increases because one of the products is a solid while one of the reactants is a liquid. I.Entropy does not change during the reaction because both sides of the reaction include the same number

G.Entropy decreases because there are substantially fewer molecules of product than of reactants.

Which of these sentences correctly states the law of conservation of mass? F.In a chemical reaction, the mass of the products cannot exceed the mass of the reactants. G.In a chemical reaction, the mass of the products is always equal to the mass of the reactants. H.In a chemical reaction, the mass of the products is always less than the mass of the reactants. I.In a chemical reaction, the mass of the products is always greater than the mass of the reactants.

G.In a chemical reaction, the mass of the products is always equal to the mass of the reactants.

Why is an input of energy needed when forming NaCl? F. to change chlorine to a gas G. to add an electron to the chlorine atom H. to remove an electron from the sodium atom I. to bring together the sodium and the chloride ions

H. to remove an electron from the sodium atom

Water boils at 100°C. Ethyl alcohol boils at 78.5°C. Which of these statements is true? F.Vapor pressure is not related to boiling point. G.Water has a higher vapor pressure at a temperature of 78.5°C. H.Ethyl alcohol has a higher vapor pressure at a temperature of 78.5°C. I.Water and ethyl alcohol have the same vapor pressure at a temperature of 78.5°C.

H.Ethyl alcohol has a higher vapor pressure at a temperature of 78.5°C.

How do citrus growers take advantage of enthalpy of fusion when they spray fruit trees to protect the fruit from freezing? F.Heat is released as water changes from gas to liquid. G.Heat is released as water changes from liquid to gas. H.Heat is released as water changes from liquid to solid. I.Heat is released as water changes from solid to

H.Heat is released as water changes from liquid to solid.

Which of these statements about the temperature of a substance is true? F.Temperature is a measure of the entropy of the substance. G.Temperature is a measure of the total kinetic energy of its atoms. H.Temperature is a measure of the average kinetic energy of its atoms. I.Temperature is a measure of the molar heat capacity of the substance.

H.Temperature is a measure of the average kinetic energy of its atoms.

(Illustration airbag)What is the purpose of the igniter in this system? F.pump air into the air bag G.prevent any reaction until there is a crash H.provide energy to start a very fast reaction that produces a gas. I.provide energy to expand air that is stored

H.provide energy to start a very fast reaction that produces a gas.

Why are the Group 17 elements, the halogens, the most reactive of the nonmetal elements? F. They have the largest atomic radii. G. They have the highest ionization energies. H. They are the farthest right on the periodic table. I. They require only one electron to fill their outer energy level.

I. They require only one electron to fill their outer energy level.

Electron configuration for bromine, whose atomic number is 35

1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p5

electron configuration of a calcium atom, whose atomic number is 20?

1s2 2s2 2p6 3s2 3p6 4s2

How many electrons are shared in the covalent bonding of two nitrogen atoms to form a nitrogen molecule? A. 2 B. 4 C. 6 D. 8

...

A sample of pure helium (4.00 g/mol) contains exactly 6.02 X 10 to the 22nd power particles. Whats the mass of the sample? A. 0.40g B. 1g C. 2g D. 4g

A. 0.40g

Which of these events occurs when an electron in an excited state returns to its ground state? A. Light energy is emitted B. Energy is absorbed by the atom C. The atoms undergoes spontaneous decay D. The charge increases because an electron is added

A. Light energy is emitted

Which term describes a scientific explanation that is supported by a large body of experimental evidence and reasoning? A.Theory B. conclusion C. Hypothesis C. Scientific Law

A. Theory

A student places a strip of pure magnesium metal into a test tube containing a dilute solution of hydrochloric acid (hydrogen chloride dissolved in water). As the magnesium disappears, bubbles of a colorless gas form and the test tube becomes hot to the touch. If a lit match is placed near the top of the test tube, the gas that has been generated burns. What is the most likely identity of the reaction product that burns in air? A. hydrogen B. magnesium C. oxygen D. oxygen and hydrogen mixture

A. hydrogen

Which of the following is a reason why most automobile manufacturers have replaced NaN3 with other compounds as the reactants for filling air bags? A.The sodium produced by the reaction is dangerous. B.The nitrogen produced by the reaction can be harmful. C.The materials used to make sodium azide are rare and expensive. D.The decomposition of sodium azide is too fast so it fills the air bags too quickly

A.The sodium produced by the reaction is dangerous.

Of these reaction types, which has only one reactant? A.decomposition B.displacement C.oxidation D.synthesis

A.decomposition

How many grams of carbon are contained in 200g of carbon dioxide? A. 27.29 B. 42.88 C. 54.58 D. 85.76

C. 54.58

At what temperature does the average kinetic energy of all particles reach a minimun? A. -580 degrees F B. 0 degrees C C. 0 K D. -273.15 K

C. 0 K

Using the mole ratio of the reactants and products in a chemical reaction, what will you most likely be able to determine? A. rate of the reaction B. energy absorbed or released by the reaction C.chemical names of the reactants and products D. mass of a product produced from a known mass of reactants

D. mass of a product produced from a known mass of reactants

What is the mole ratio of CO2 to C6H12O6 in the combustion reaction C6H12O6 + 6O2 -> 6CO2 + 6H2O? A) 1:1 B) 1:2 C) 1:6 D) 6:1

D) 6:1

What type of chemical reaction involves the exchange of ions of two compounds in an aqueous solution to form two new compounds? A) Synthesis B) Decomposition C) Single-displacement D) Double-displacement

D) Double-displacement

How many moles of oxygen atoms are there in 100 moles of carbon dioxide? A. 66.7 B. 72.7 C. 100 D. 200

D. 200

What is the boiling point of water expressed in Kelvin? A. -273.15 K B.0 K C.273.15 K D. 373.15 K

D. 373.15 K

What's the empirical formula of calcium phosphate (ions: Ca 2+charge and PO4 3- charge)? A. CaPO4 B. Ca2PO4 C. Ca3PO4 D. Ca3P2O8

D. Ca3P2O8

What would cause scientists to change the current model of the atom? A.Opinions of a majority of prominent scientist favor a new model B. Discovery of new evidence supporting the theory C.Evidence that electrons act as both particles and waves D. Discovery of properties of atoms or particles, inconsistent with the current atomic theory

D. Discovery of properties of atoms or particles, inconsistent with the current atomic theory

Which of the following can achieve the same electron configuration as a noble gas when the atom forms an ion? A. argon C. nickel B. iron D. potassium

D. potassium

Write a net ionic equation, excluding spectator ions, for the reaction: Mg(s) + Zn(NO3)2(aq) Zn(s) + Mg(NO3)2(aq)

Mg(s) + Zn2+(aq) Mg2+(aq) + Zn(s)

Identify the limiting and excess reactants in the production of nitric acid when nitrogen dioxide from combustion of fossil fuels reacts with water vapor in the air.

The limiting reactant is nitrogen dioxide and the excess reactant is water

Use the electron dot structure to predict the shape of an aluminum trichloride molecule. a. Pyramid b. Trigonal Planar c. Linear d. "T" shape

b. Trigonal Planar

Which is the source of energy used in the photosynthesis reaction that makes sugar from carbon dioxide and water? A.Air B. Sunlight C. water D. minerals

b. sunlight

How does the polarity of the bond between a halogen and hydrogen relate to the number of electrons of the halogen atom? a. Polarity is not related to the number of electrons of the halogen atom. b. Polarity decreases as the number of unpaired halogen electrons increases c. Polarity decreases as the total number of halogen electrons increases d. polarity decreases as the number of valence electrons of the halogen atom increases

c. Polarity decreases as the total number of halogen electrons increases

Why do molten ionic compounds generally conduct electric current well, whereas molten covalent compounds generally do not? a. Ionic compounds are more soluble in water. b. Ionic compounds have more electrons than compounds. c. When they melt, ionic compounds separate into charged particles. d. Most ionic compounds contain metal atom which carries the electric current

c. When they melt, ionic compounds separate into charged particles.