Make your own free website on
Equations and Reactions Study Guide
Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
____    1.    A chemical formula written over the arrow in a chemical equation signifies
a. a byproduct. c. a catalyst for the reaction.
b. the formation of a gas. d. an impurity.

____    2.    What is the formula mass of magnesium chloride, MgCl2?
a. 46 amu c. 95.211 amu
b. 59.763 amu d. 106.354 amu

____    3.    The electron notation for aluminum (atomic number 13) is
a. 1s2 2s2 2p3 3s2 3p3 3d1. c. 1s2 2s2 2p6 3s2 3p1.
b. 1s2 2s2 2p6 3s2 2d1. d. 1s2 2s2 2p9.

_    4.    Name the compound Zn3(PO4)2.
a. zinc potassium oxide c. zinc phosphate
b. trizinc polyoxide d. zinc phosphite

____    5.    In what kind of reaction do two or more substances combine to form a new compound?
a. decomposition reaction c. double-replacement reaction
b. ionic reaction d. synthesis reaction

____    6.    What is the formula mass of (NH4)2SO4?
a. 114.09 amu c. 128.06 amu
b. 118.34 amu d. 132.13 amu

____    7.    In what kind of reaction do the ions of two compounds exchange places in aqueous solution to form two new compounds?
a. synthesis reaction c. decomposition reaction
b. double-replacement reaction d. combustion reaction

____    8.    The molar mass of CS2 is 76.14 g/mol. How many grams of CS2 are present in 10.00 mol?
a. 0.13 g c. 10.00 g
b. 7.614 g d. 761.4 g

____    9.    What is the formula for barium hydroxide?
a. BaOH c. Ba(OH)2
b. BaOH2 d. Ba(OH)

___    10.    What is the oxidation number of magnesium in MgO?
a. -1 c. +1
b. 0 d. +2

____    11.    Which formula does NOT represent a molecule?
a. H2O (water) c. CO2 (carbon dioxide)
b. NH3 (ammonia) d. NaCl (table salt)

____    12.    What is the balanced equation when aluminum reacts with copper(II) sulfate?
a. Al + Cu2S ® Al2S + Cu c. Al + CuSO4 ® AlSO4 + Cu
b. 2Al + 3CuSO4 ® Al2(SO4)3 + 3Cu d. 2Al + Cu2SO4 ® Al2SO4 + 2Cu

____    13.    What is the formula for the compound formed by calcium ions and chloride ions?
a. CaCl c. CaCl3
b. Ca2Cl d. CaCl2

____    14.    What is the oxidation number of sulfur in SO2?
a. 0 c. +2
b. +1 d. +4

____    15.    What is the formula for aluminum sulfate?
a. AlSO4 c. Al2(SO4)3
b. Al2SO4 d. Al(SO4)3

____    16.    What is the oxidation number of oxygen in peroxides?
a. -2 c. 0
b. -1 d. +2

____    17.    What is the name of a list of elements arranged according to the ease with which they undergo certain chemical reactions?
a. reactivity list c. activity series
b. reaction sequence d. periodic list

____    18.    The activity series of metals indicates the ease with which metal
a. atoms gain neutrons. c. atoms form covalent bonds.
b. nuclei fuse. d. atoms lose electrons.

____    19.    How many atoms of fluorine are present in a molecule of carbon tetrafluoride, CF4?
a. 1 c. 4
b. 2 d. 5

____    20.    What is the spectator ion in the equation Cu2+(aq) + Zn2+(aq) + 2S2-(aq) ® CuS(s) + ZnS(s)?
a. Cu2+(aq) c. S2-(aq)
b. Zn2+(aq) d. none of the above

____    21.    A molecular compound has the empirical formula XY3. Which of the following is a possible molecular formula?
a. X2Y3 c. X2Y5
b. XY4 d. X2Y6

____    22.    What is the oxidation number of carbon in CI4?
a. -4 c. +4
b. +1 d. +5

____    23.    What is the oxidation number of an uncombined element?
a. -1 c. +1
b. 0 d. 8

____    24.    When a binary compound decomposes, what is produced?
a. an oxide c. a tertiary compound
b. an acid d. two elements

____    25.    When potassium reacts with water, one product formed is
a. hydrogen gas. c. potassium oxide.
b. oxygen gas. d. salt.

____    26.    The reaction of calcium oxide (CaO) with water yields
a. calcium and oxygen gas. c. calcium and a salt.
b. calcium hydroxide. d. carbon dioxide and water.

____    27.    Which model of the atom explains why excited hydrogen gas gives off certain colors of light?
a. the Bohr model c. Rutherford's model
b. the quantum model d. Planck's theory

____    28.    With the quantum model of the atom, scientists have come to believe that determining an electron's exact location around the nucleus
a. is impossible.
b. can be done before 2005.
c. can be done easily.
d. can be done only with specialized equipment.

____    29.    The reaction Pb(NO3)2(aq) + 2KI(aq) ® PbI2(s) + 2KNO3(aq) is a
a. double-replacement reaction. c. decomposition reaction.
b. synthesis reaction. d. combustion reaction.

____    30.    Knowledge about what products are produced in a chemical reaction is obtained by
a. inspecting the chemical equation. c. laboratory analysis.
b. balancing the chemical equation. d. writing a word equation.

____    31.    What is the oxidation number of hydrogen in compounds containing metals?
a. -1
b. 0
c. +1
d. It is equal to the charge on the metal ion.

____    32.    What is the oxidation number of oxygen in H2O2?
a. -2 c. +2
b. -1 d. +4

____    33.    When the equation Fe3O4 + Al ® Al2O3 + Fe is correctly balanced, what is the coefficient of Fe?
a. 3 c. 6
b. 4 d. 9

____    34.    A formula that shows the simplest whole-number ratio of the atoms in a compound is the
a. molecular formula. c. structural formula.
b. ideal formula. d. empirical formula.

____    35.    What is the percentage composition of chlorine in NaCl?
a. 35.45% c. 60.7%
b. 50% d. 64.5%

____    36.    The Pauli exclusion principle states that no two electrons in the same atom can
a. occupy the same orbital. c. have the same set of quantum numbers.
b. have the same spin quantum numbers. d. be at the same main energy level.

____    37.    What is the net ionic equation for the precipitation reaction between copper(II) chloride and sodium hydroxide?
a. Cu2+(aq) + 2OH-(aq) ® Cu(OH)2(s)
b. Na+(aq) + Cl-(aq) ® NaCl(s)
c. Cu2+(aq) + 2OH-(aq) + 2Cl-(aq) ® Cu(OH)2(s) + 2Cl-(aq)
d. Cu2+(aq) + 2Cl-(aq) + 2Na+(aq) + 2OH-(aq) ® Cu(OH)2(s) + 2NaCl(s)

____    38.    A quantum of electromagnetic energy is called a(n)
a. photon. c. excited atom.
b. electron. d. orbital.

____    39.    What is the empirical formula for a compound that is 31.9% potassium, 28.9% chlorine, and 39.2% oxygen?
a. KClO2 c. K2Cl2O3
b. KClO3 d. K2Cl2O5

____    40.    Which of the following is the right side of the equation for dissolving K2S(s)?
a. 2K+(aq) + S2-(aq) c. K2+(aq) + S2-(aq)
b. K22+(aq) + S2-(aq) d. 2K(aq) + S(aq)

____    41.    To find the molecular formula from the empirical formula, one must determine the compound's
a. density. c. structural formula.
b. formula mass. d. crystal lattice.

____    42.    What is the electron configuration for nitrogen, atomic number 7?
a. 1s2 2s2 2p3 c. 1s2 2s3 2p1
b. 1s2 2s3 2p2 d. 1s2 2s2 2p2 3s1

____    43.    The decomposition of a substance by an electric current is called
a. electrolysis. c. ionization.
b. conduction. d. transformation.

____    44.    The complete balanced equation for the reaction between zinc hydroxide and acetic acid is
a. ZnOH + CH3COOH ® ZnCH3COO + H2O.
b. Zn(OH)2 + CH3COOH ® Zn + 2CO2 +3H2O.
c. Zn(OH)2 + 2CH3COOH ® Zn(CH3COO)2 + 2H2O.
d. Zn(OH)2 + 2CH3COOH ® Zn(CH3COO)2 + H2 + O2.

____    45.    Oxides of active metals, such as CaO, react with water to produce
a. metal carbonates. c. acids.
b. metal hydrides. d. metal hydroxides.

____    46.    What is the sum of the atomic masses of all the atoms in a formula for a compound?
a. molecular mass c. atomic mass
b. formula mass d. actual mass

____    47.    How many moles of ions are produced by the dissociation of 1 mol of MgCl2?
a. 0 c. 2 mol
b. 1 mol d. 3 mol

____    48.    Name the compound SO3.
a. sulfur trioxide c. selenium trioxide
b. silver trioxide d. sodium trioxide

____    49.    How many moles of ions are produced by the dissociation of 1 mol of Al2(CO3)3?
a. 2 mol c. 5 mol
b. 4 mol d. 11 mol

____    50.    In a polyatomic ion, the algebraic sum of the oxidation numbers of all atoms is equal to
a. 0. c. 10.
b. the number of atoms in the ion. d. the charge of the ion.

____    51.    What is the oxidation number of oxygen in most compounds?
a. -8 c. 0
b. -2 d. +1

____    52.    Which coefficients correctly balance the formula equation CaO + H2O ® Ca(OH)2?
a. 2, 1, 2 c. 1, 2, 1
b. 1, 2, 3 d. 1, 1, 1

____    53.    The emission of electrons from metals that have absorbed photons is called the
a. interference effect. c. quantum effect.
b. photoelectric effect. d. dual effect.

____    54.    The equation A + X ® AX is the general equation for a(n)
a. combustion reaction. c. synthesis reaction.
b. ionic reaction. d. double-replacement reaction.

____    55.    What is the percentage composition of CF4?
a. 20% C, 80% F c. 16.8% C, 83.2% F
b. 13.6% C, 86.4% F d. 81% C, 19% F

____    56.    What is the oxidation number of hydrogen in KH?
a. -1 c. +1
b. 0 d. +2

____    57.    What is the net ionic equation for the precipitation reaction between silver nitrate solution and sodium sulfide solution?
a. 2Ag+(aq) + 2NO3-(aq) + 2Na+(aq) + S2-(aq) ® Ag2S(s) + 2Na+(aq) + 2NO3-(aq)
b. 2Ag+(aq) + S2-(aq) ® Ag2S(s)
c. Na+(aq) + NO3-(aq) ® NaNO3(s)
d. 2Ag+(aq) + 2NO3-(aq) + 2Na+(aq) + S2-(aq) ® Ag2S(s) + 2NaNO3(s)

____    58.    How many Cl- ions are present in 2.00 mol of KCl?
a. 12.04 ´ 1023 c. 2.00
b. 6.02 ´ 1024 d. 0.5

____    59.    An active metal and a halogen react to form a(n)
a. salt. c. acid.
b. hydroxide. d. oxide.

____    60.    Which equation is NOT balanced?
a. 2H2 + O2 ® 2H2O
b. 4H2 + 2O2 ® 4H2O
c. H2 + H2 + O2 ® H2O + H2O
d. 2H2 + O2 ® H2O

____    61.    A solid produced by a chemical reaction in solution that separates from the solution is called
a. a precipitate. c. a molecule.
b. a reactant. d. the mass of the product.

____    62.    The formulas for the products of the reaction between sodium hydroxide and sulfuric acid are
a. Na2SO4 and H2O. c. SI4 and Na2O.
b. NaSO4 and H2O. d. S + O2 and Na.

____    63.    What is the oxidation number of hydrogen in most compounds?
a. -1
b. 0
c. +1
d. It is equal to the algebraic sum of the oxidation numbers of the nonmetals.

____    64.    The molar mass of H2O is 18.015 g/mol. How many grams of H2O are present in 0.20 mol?
a. 0.2 g c. 35.9 g
b. 3.6 g d. 89.9 g

____    65.    The molar mass of LiF is 25.94 g/mol. How many moles of LiF are present in 10.37 g?
a. 0.3998 mol c. 2.500 mol
b. 1.333 mol d. 36.32 mol

____    66.    A chemical reaction has NOT occurred if the products have
a. the same mass as the reactants.
b. less total bond energy than the reactants.
c. more total bond energy than the reactants.
d. the same chemical properties as the reactants.

____    67.    When heated, metallic chlorates decompose into
a. metallic oxides and chlorine.
b. metallic chlorides and oxygen.
c. a metal and a compound of chlorine and oxygen.
d. a metal, chlorine, and oxygen.

____    68.    Magnesium bromide + chlorine yield
a. Mg and BrCl. c. MgBrCl.
b. MgCl and Br2. d. Mg(Cl)2 and Br2.

____    69.    A bright-line spectrum of an atom is caused by the energy released when electrons
a. jump to a higher energy level.
b. fall to a lower energy level.
c. absorb energy and jump to a higher energy level.
d. absorb energy and fall to a lower energy level.

____    70.    A compound's empirical formula is CH. If the formula mass is 26 amu, what is the molecular formula?
a. C2H2 c. CH4
b. CH3 d. C4H

____    71.    To balance a chemical equation, it may be necessary to adjust the
a. coefficients. c. formulas of the products.
b. subscripts. d. number of products.

____    72.    In a compound, the algebraic sum of the oxidation numbers of all atoms equals
a. 0. c. 8.
b. 1. d. the charge on the compound.

____    73.    Name the compound N2O4.
a. sodium tetroxide c. nitrous oxide
b. dinitrogen tetroxide d. binitrogen oxide

____    74.    How many quantum numbers are needed to describe the energy state of an electron in an atom?
a. 1 c. 3
b. 2 d. 4

____    75.    The molar mass of NO2 is 46.01 g/mol. How many moles of NO2 are present in 114.95 g?
a. 0.4003 mol c. 2.498 mol
b. 1.000 mol d. 114.95 mol

____    76.    What is the balanced equation for the combustion of sulfur?
a. S(s) + O2(g) ® SO(g) c. 2S(s) + 3O2(g) ® SO3(s)
b. S(s) + O2(g) ® SO2(g) d. S(s) + 2O2(g) ® SO42-(aq)

____    77.    If a certain metal is placed in an ionic solution containing another metal and no reaction occurs, then the metal originally in the solution is
a. a halogen. c. not on the activity series.
b. higher on the activity series. d. unreactive.

____    78.    What is the small whole number that appears in front of a formula in a chemical equation?
a. a subscript c. a ratio
b. a superscript d. a coefficient

____    79.    A compound contains 259.2 g of F and 40.8 g of C. What is the empirical formula for this compound?
a. CF4 c. CF
b. C4F d. CF2

___80.    Group 1 metals react with water to produce metal hydroxides and
a. metal hydroxides. c. oxygen.
b. hydrochloric acid. d. hydrogen.

___    81.    In an equation, the symbol for a substance in water solution is followed by
a. (1). c. (aq).
b. (g). d. (s).

__    82.    Which of the following is the right side of the equation for dissolving Al(NO3)3?
a. Al+ + (NO3)3- c. Al3+ + NO33-
b. Al3+(aq) + 3NO3-(aq) d. Al3-(aq) + 3NO3+(aq)

__    83.    The region outside the nucleus where an electron can most probably be found is the
a. electron configuration. c. s sublevel.
b. quantum. d. electron cloud.

Short Answer

    84.    How does the figure above illustrate the Pauli exclusion principle?
    85.    How does the figure above illustrate Hund's rule?
    86.    The electron configuration for nitrogen is 1s2 2s2 2p3. What does the 3 in 2p3 mean?
    87.    The molar mass of copper is 63.55 g/mol, the molar mass of sulfur is 32.07 g/mol, and the molar mass of oxygen is 16.00 g/mol. Calculate the molar mass of copper(II) sulfate, CuSO4.

    88.    Use the symbols for the noble gases to write the electron configuration represented in the figure above.
Equations and Reactions Test
Answer Section
1.    C  2.C  3. C  4.C5.D  6.  D  7.B  8.D9.C 10.D  11.D  12.B13.D14.D15.C16.B17.C
18.    D19.C20.D21.D22.C23.B24.D25.A26.B27.A28.A29.A30.C31.A

32.    B33.D34.D35.C36.C37.A38.A39.B40.A41.B42.A43.A44.C45.D

46.    B47.D48.A49.C50.D51.B52.D53B54.C55.B56.A57.B58.A59.A60.D61.A62.A
    84.    According to the Pauli exclusion principle, no two electrons can have the same set of four quantum numbers. Therefore, no more than two electrons can occupy an orbital, and these two must have opposite spins.

    85.    According to Hund's rule, the arrangement of electrons with the maximum number of unpaired electrons is the most stable arrangement.

    86.    The 3 in 2p3 indicates that three electrons are in the p orbitals of the second energy level.
    87.    159.62 g/mol CuSO4
63.55 g/mol Cu + 32.07 g/mol S + (4 ´ 16.00 g/mol O) = 159.62 g/mol CuSO4

    88.    [Ne] 3s2 3p4