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  Balancing Equations Level 1 Multiple Choice   1) In a balanced chemical equation     l) coefficients are equal;      2) atoms are conserved;     3) molecules are equal;          4) energy is always produced;          5) none of these

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Balancing Equations

Level 1

Multiple Choice

 

1) In a balanced chemical equation     l) coefficients are equal;      2) atoms are conserved;

    3) molecules are equal;          4) energy is always produced;          5) none of these.

 

2. Which of the following statements about a chemical reaction is false?

    1) The mass of the reactants consumed equals the mass of the products formed.

    2) No atoms are created or destroyed in the reaction.

    3) The number of moles of products equals the number of moles of reactants.

    4) The reaction produces new molecules through rearrangement of atoms.

 

3. To satisfy the law of conservation of matter, an equation

    1) must be written in words;           2) should show the atomic mass of both reactants

    and products;            3) must be balanced;           4) must indicate the physical state of

    each of the reactants and products.

 

4. The number of atoms of oxygen indicated by the formula Ca₃(PO₄)₂  is:

    1) 8;                 2) 7;                 3) 3;                4) 4;                5) 12.

 

5. Which of the following expressions represents two molecules of water?

    1) H₂O              2) H₂O₂              3) 2 H₂O              4) 2 HO₂              5) none of these

 

6. The smallest quantity of an element that can take part in a chemical reaction is called:

    1) a molecule;               2) an atom;               3) a block;                 4) an angstrom unit.

 

7. In a balanced equation the numerical coefficients arrived at in balancing the equation

    are identical with                                                    

    1) the molar volumes.                                 3) the number of moles of each substance.            

    2) the number of gram-atoms.                    4) the specific gravity of each gas.

 

8. The proportion in which elements combine to form a given compound

    1) never varies.                                           3) varies when stirred.

    2) varies when heated.                                4) varies when mixed explosively.

 

9. The ratio of the volume of nitrogen to that of the ammonia in the reaction 

    N₂  + 3 H₂  à 2 NH₃   is       1) 1:2;              2) 1:3;              3) 3:2;              4) 2:3.

 

10. The breaking down of a complex substance to form two or more simpler substances is:

    1) decomposition;        2) composition;        3) replacement;        4) double replacement.

 

11. The substances to the left of the arrow in a chemical equation are called

    1) coefficients;                2) products;                3) subscripts;                4) reactants.

 

12. In every balanced equation, one should find represented on both sides the same number

    of:    1) atoms;                2) coefficients;                3) isotopes;                4) molecules.

 

13. A gas whose molecule is monatomic is

    1) oxygen;             2) helium;             3) nitrogen;            4) chlorine;           5) hydrogen.

 

14. A particle which enters into a chemical reaction is

    1) an electron;         2) a proton;        3) a positron;         4) a neutron;         5) all of these.

 

15. C  +  O₂  à  CO₂   means which of the following?

    1) When carbon combines with oxygen, carbon dioxide is formed.

    2) Calcium and ozone will form a stable compound.

    3) Carbon monoxide is released when gasoline is burned.

    4) The air contains two molecules of oxygen and one of carbon.

 

16. A hypothetical element, Z, forms a chloride with the formula ZC1₅.  What is the

       most probable formula for its oxide?

       1)  ZO₂                  2) ZO₅                  3) Z₂O₅                  4) Z₅O₂

 

17. The smallest particle of an element that can take part in a chemical change is

    1) an atom;              2) a neutron;               3) a molecule;               4) an oxide.

 

18. When a correctly written formula equation, is balanced

    1) the total number of atoms on one side must equal the total number of  atoms of

       the other side.

    2) the sum of the coefficients on the left side must equal the coefficient sum on the

        right side.

    3) the number of subscripts on each side must be equal.

    4) all molecules must be diatomic.

 

19. Balancing a formula equation is achieved by

    1) adjusting the subscripts in the formulas.

    2) adjusting the coefficients to the smallest possible whole number ratio.

    3) adjusting the number of elements produced.

    4) adjusting an incorrect formula of a compound.

 

20. In balanced equations, both sides always contain the same number of

   1) atoms;                 2) coefficients;                 3) ions;                 4) molecules.

 

21. In a chemical reaction,    1) atoms may be rearranged;        2) atoms may be destroyed;       

   3) atoms may be created;         4) all atoms become molecules.

 

22. The total number of atoms represented by the formula  K₃Fe(CN)₆  is

   1) 6;               2) 10;                3) 13;                4) 14;                5) 16.

 

23. A word equation states all of the following except:

   1) the substances which enter into the chemical reaction.

   2) the substances which are produced by a chemical reaction.

   3) the quantities of substances involved.

   4) an experimental fact or facts.

 

24. The correct formula for three molecules of oxygen is

   1) O₃;                 2) O₂;                 3) 3 O₂;                 4) 3 O;                5) 2 O₃.

 

25. Of the following words, the one used to represent a chemical reaction is

   1) an atom;           2) a formula;          3) an equation;          4) a symbol;         5) a mole.

 

26. A balanced chemical equation shows that in any chemical reaction,

   1) some new atoms may be created.                 3) atoms are rearranged.
   2) some atoms may be destroyed.                     4) the coefficients remain the same.

 

27. To balance an equation, we use      1) exponents;           2) subscripts;

   3) superscripts;             4) coefficients;            5) all of these.

 

28. The substances to the right of the arrow in a chemical equation are called

    1) subscripts;              2) products;              3) coefficients;              4) reactants.

 

29. The process whereby a chemist produces a new material by combining elements is called

    1) hydrolysis;               2) electrolysis;               3) analysis;               4) synthesis.

 

30. The chemical reaction represented by the equation:  2 NaOH  +  H₂SO₄  à  ________,

    is an example of      1) double replacement;            2) single replacement;        

    3) decomposition;            4) direct combination.

 

31. The reaction between zinc and  hydrogen chloride is       l) direct composition;     

    2) single replacement;              3) neutralization;              4) double replacement.

 

32. The combining of simple substances to form a more complex substance is

    1) decomposition;       2) analysis;       3) fission;       4) replacement;       5) composition.

 

33. The valence number of each element always remains unchanged in

    1) composition reactions.                              3) single replacement reactions.

    2) decomposition reactions.                          4) double replacement reactions.

 

34. The reaction: iron  +  oxygen  à  iron oxide, is an example of     1) direct compo­sition;

    2) decomposition;             3) single replacement;             4) double replacement.

 

35. The type of reaction represented by the expression _____  +  _____  à  AY  +  BX  is

    1) composition;        2) decomposition;         3) replacement;         4) double replacement.

 

36. An example of a double replacement reaction is

    1) 2 HgO  à  2 Hg + O₂.                                                    3) Zn + 2 HC1  à   ZnCl₂ + H₂.

    2) Al₂(SO₄)₃   +  3 Ca(OH)₂ à   2 Al(OH)₃   +  3 CaSO₄.    4) 2 H₂  + O₂  à  2 H₂O.

                                                                                                 5) 3 H₂   +  N₂  à    2 NH₃.

 

37. Which of the following represents a single replacement type of reaction?

    1) Ni  +  S  à  NiS                                    3) CuSO₄  +  Fe  à  FeSO₄  +  Cu

    2) 2 H₂O  à  2 H₂ + O₂                                           4) C  +  O₂  à  CO₂

 

38. The type of reaction represented by the expression  _____ + _____  à  BZ  is a:

    1) composition reaction.                             3) replacement reaction.

    2) decomposition reaction.                         4) double replacement reaction.

 

39.The type of reaction represented by the expression, CT  à ______         is a

    1) composition reaction.        3) replacement reaction.

    2) decomposition reaction.    4) double replacement reaction.    5) condensation reaction.

 

40. The combination of two or more simple substances to form a more complex substance

     is     1) composition;              2) decomposition;                3) condensation;         

     4) replacement;               5) double replacement.

 

41. The type of reaction represented by the generalized form of an equation

   Y  +  BX  à  BY +  X   is a      1) composition reaction;           2) decomposition

   reaction;           3) replacement reaction;           4) double replacement reaction;     

   5) condensation reaction.

 

42. An example of a replacement reaction is:

   1) H₂O  +   SO₂  à  H₂SO₃.                       3) Cl₂  +   2 KI  à  2 KC1 +  I₂.
   2) 2 H₂  +   O₂   à  2 H₂O.                         4) Fe  +  S   à   FeS.

 

43. All of the following reactions belong to one type except

   1) 2 NaCl  à  2 Na  +  Cl₂.                      3) Ca(OH)₂  à  CaO  +  H₂O

   2) CaCO₃  à .CaO  +  CO₂                      4) Zn  +  H₂SO₄  à  ZnSO₄  +  H₂.

 

44. The balanced equation for the synthesis of ammonia is

   1) N₂   +  3 H₂   à  2 NH₃                                               3) 2 N  +  3 H₂  à  2 NH₃
   2) N₂O  +  3 H₂O  à  2 NH₃  +  2 O₂             4) 4 NO  +  6 H₂O  à  4 NH₃   +  5 O₂

 

45. Which set of coefficients correctly balances the reaction  K₃PO₄  +  MgCl₂  à  ______?

    1) 1, 3, 1, 6          2) 2, 3, 1, 6        3) 2, 3, 2, 1          4) 3, 2, 1, 6          5) none of these

 

46. The coefficient X which should appear when the following molecular equation,

    C₂H₆   +  X O₂ à  CO₂  +  H₂O, is correctly balanced is

    1) 7;                 2) 2;                 3) 8;               4) 6;              5) none of these.

 

 47. Consider the unbalanced expression:  Cu (s)  +  NO₃^- (aq)  +  H⁺(aq) à

    Cu⁺²(aq)  +  NO(g) + H₂O(l).  Which set of coefficients correctly balances the equation?

    1) 4,5,3,8,2,3                 2) 2,4,3,8,3,3                 3) 3,2,8,7,2,4                 4) 3,2,8,3,2,4

 

 48. When the equation SbCl₃  +  H₂S  à  Sb₂S₃  +  ________  is balanced, the coefficient

    of H₂S is     1) 4;               2) 2;               3) 5;               4) 6;               5) none of these.

 

 49. When the equation  ZnS  +  O₂   à   ZnO  +  SO₂   is balanced, the coefficient of

    the reactant  O₂  will be      l) 1;               2) 2;               3) 3;               4) 4.

 

50. Which of the following sets of coefficients correctly balances the equation:

    Ca₃( PO₄)₂   +   H₂SO₄  à  Ca(H₂PO₄)₂  +  CaSO₄?

    1) 1, 1, 1, 1          2) 1, 2, 1, 2          3) 1, 3, 1, 2           4) 1, 1, 3, 2          5) none of these

 

51. Consider the unbalanced expression: CH₃CH₂CHO(l)  +  O₂(g)  à  CO₂ (g)  +  H₂O(g).

    Which set of coefficients balances the equation?

    1) 2, 8, 3, 6        2) 3, 8, 6, 6        3) 1, 4, 3, 2        4) 1, 8, 3, 3        5) 1, 4, 3, 3

 

52. The coefficient X which should appear when the following molecular equation,

    x HC1  +  MnO₂   à  MnCl₂  +  H₂O  +  Cl₂, is balanced correctly is

    1) 1;                2) 2;                3) 3;                4) 4;               5) 5.

 

53. The coefficient X which should appear when the equation,

    C₂H₂  +  xO₂   à  CO₂  +  H₂O,  is balanced correctly is      

    1) 1;               2) 2;               3) 3;              4) 4;               5) 5.

 

54. The term X in the correctly balanced equation, 2 H₂S  +  O₂   à   2 H₂O  +  X  is

    1) 2 H₂SO₄;              2) 2 S;             3) 2 SO₄;              4) 2 SO₂;              5) 2 SO₃.

 

55. Which set of coefficients balances the equation for the complete combustion of ethane?

                                    C₂H₆  +    O₂    à  CO₂   +   H₂O      

    1) 1, 3, 2, 3                2) 1, 6, 2, 6                 3) 2, 6, 4, 5                4) 2, 7, 4, 6

                                                                                                                                                  

56. The balanced equation for the single replacement reaction between copper and

    silver nitrate is
    1) Cu  +  AgNO₃  à  AgCuNO₃.             3) Cu + 2 AgNO₃  à   Cu(NO₃)₂  +  2 Ag.
    2) Cu  +  AgNO₃   à  no reaction.            4) Cu  + AgNO₃  à   Ag⁺ +  Cu⁺ +  NO₃^-.

 

57. In the thermite reaction iron is produced from iron ore, Fe₃O₄.  Which expression for

    this reaction is balanced?

    1) Fe₃O₄  +  2 Al  à  A1₂O₃   +  3 Fe                  3) 3 Fe₃O₄   +  4 A1  à  .4 Al₂O₃   +  9 Fe

    2) 2 Fe₃O₄   +  2 Al  à  2 A1₂O₃   +  6 Fe            4) 3 Fe₃O₄   +  8 A1  à  4 A1₂O₃   +  9 Fe

 

58. The coefficient X which should appear when the molecular equation 

    Al  +  X HC1  à  ______ + _____ , is correctly balanced is      

    1) 8;                 2) 4;                 3) 3;                 4) 6;                 5) 5.

 

59. What is the coefficient of P when the expression is balanced?

                          H₂SO₄   +  P  à  H₃PO₄   +  H₂O  +  SO₂

    1) 1                 2) 2                 3) 5                 4) 4                 5) none of these

                                                                               

60. Among the following equations, the one which is correctly balanced is

    1) C  +  O₂  à  CO₂.                3) HgO  à  Hg  +  O₂.

    2) 2 H₂O  à  H₂  +  O₂.      4) 2 Zn  +  Cl₂  à ZnCl₂   +  H₂.     5) 2 NH₃  à  N₂   +  2 H₂.

 

61. The expression for pentane, C₅H₁₂, burning in oxygen is

    C₅H₁₂(g)  +  O₂(g)  à  CO₂(g) + H₂O(g). What set of coefficients balances the equation?

    1) 1, 8, 5, 6          2) 2, 8, 10, 6          3) 1, 8, 5, 12          4) 1, 11, 5, 12          5) 3, 8, 7, 9

 

62. When the equation  Cu₂S  +  O₂   à   CuO  +  SO₂   is balanced, the coefficient of

    the reactant Cu₂S will be       1) 1;                2) 2;                3) 3;                4) 4.

 

63. Among the following equations the one which is correctly balanced is:

    1) S  +   O₂  à  SO₂ .                              3) H₂   +   O₂  à  H₂O.
    2) 2 HgO  à  Hg  +  O₂ .                        4) Zn  +  HC1  à  ZnC1₂   +  H₂.

 

64. Which expression for the complete combustion of pentane, C₅H₁₂, is balanced?

    1) 2 C₅H₁₂   +  8 O₂  à 10 CO₂  + 12 H₂O       3) C₅H₁₂  +  8 O₂  à  5 CO₂   +  6 H₂O

    2) 2 C₅H₁₂   +  5 O₂  à 10 CO₂  +  6 H₂O        4) C₅H₁₂   +  8 O₂  à  5 CO₂  + 12 H₂O

 

65. The coefficient X which should appear when the following molecular equation,

   SbCl₃   +  H₂S  à  Sb₂S₃  +  X HC1, is balanced correctly is

    1) 8;                 2) 9;                 3) 2;               4) 3;                5) 6.

 

66. The coefficient X which should appear when the equation, 

   A1₂(SO₄)₃  +  Ca(OH)₂    à  X CaSO₄  +  _____ ,  is balanced correctly is:

   1) 1;                2) 2;                3) 3;                4) 4;                5) some other number.

 

67. Balance the following expression. Select the set of coefficients which corresponds

   to those in the balanced equation.    NH₄OH  +  FeCl₃  à  _____  + _____ .

   1) 1, 1, 3, 1           2) 2, 2, 3, 2            3) 3, 1 , 3 , 1            4) l, 3, 3, 1            5) 2, 3, 2, 3

 

68. When the equation  Fe  +  _____  à  Fe₃O₄  +  H₂  is correctly balanced, the

   coeffici­ent for H₂ will be       1) 1;             2) 2;               3) 3;           4) 4;             5) 5.

 

69. PbO₂   +  HC1  à  PbCl₂  +  Cl₂   +  H₂O.   When this reaction is properly balanced with

   whole number coefficients, the coefficient in front of HC1 is

   1) 2;                2) 3;                3) 4;                4) 6;                5) none of these.

 

70. Which equation is correctly balanced?

   1) CaO  +   2 H₂O  à  Ca(OH)₂           3) Ca(OH)₂   +  2 H₃PO₄  à  Ca₃(PO₄)₂   + 3 H₂O

   2) NH₃  +  2 O₂  à  HNO₃   +  H₂O       4) Cu  +  H₂SO₄   à  CuSO₄   +  H₂O  +  SO₂

 

71. In the reaction Al  +  O₂  à  __________ , how many moles of aluminum oxide are

   produced from one mole of aluminum?

   1) 0.5 mole        2) 2.0 moles          3) 3.0 moles         4) 4.0 moles         5) none of these  

 

72. In the balanced equation Al₂(SO₄)₃  +  Ca(OH)₂   à  ____________ ,  the Ca(OH)₂

   has the coefficient of     1) 1;            2) 2;             3) 3;             4) 4;             5) 5.

                                                                                             

73. What is the coefficient of hydrogen sulfide when this equation is balanced?

   H₂S  +  SO₂   à  S  +  H₂O      1) 1           2) 2            3) 3           4) 4           5) 5

 

74. Consider the equation  CH₄(g)  +  2 O₂(g)  à  CO₂(g)  +  2 H₂O(g). The number

   of  atoms of oxygen required to react with 1 molecule of CH₄ is

   1) 4;                2) 10;                3) 20;                 4) 45.

 

75. Pentane gas, C₅H₁₂,  is combined with oxygen gas to yield water and carbon dioxide.

   Which set of coefficients balances this equation?

   1) 2, 4, 5, 6          2) 1, 8, 6, 5          3) 4, 5, 7, 2          4) 4, 5, 2, 7          5) none of these

 

76. Which set of coefficients balances this equation?

                             CH₄(g)   à   C₃H₈(g)  +  H₂(g).

   1) 3, 1, 1               2) 3, 2, 1               3) 3, 1, 2               4) 6, 2, 2               5) 6, 2, 6

 

77. The balanced equation for the commercial production of iron III chloride is

   1) 2 Fe  +  3  Cl₂   à  2 FeCl₃                                     3) 3 Fe  +  2 C1₂    à   2 FeC1₃

   2) 3 Fe  +  3 C1₂   à  2 FeCl₃                                      4) Fe  +  Cl₂   à  FeC1₃.

                                                                                                     

78. When the equation the  CS₂  +  O₂   à  CO₂  is correctly balanced,

   coefficient in front of O₂ will be:      1) 1;              2) 2;              3) 3;              4) 4.

 

79. The term X in the correctly balanced chemical reaction 

   2 NaC1O₂  +  Cl₂   à  2 C1O₂   +  X ,  is

   1) Na₂C1₂;           2) 2 NaCl;            3) Na₂O;          .4) 3 NaCl;           5) none of these.

 

80. Given the unbalanced equation:  (NH₄)₃PO₄  +  Ba(NO₃)₂   à  __________ .     

   What is the coefficient in front of ammonium nitrate when the equation is correctly

   balanced with the smallest whole-number coefficients?
   1) 6               2) 2               3) 3               4) 4               5) 5

 

81. What is the coefficient of NH₄Br in the following equation when it is balanced?

            Al₂(SO₄)₃  +  NH₄Br  à  __________ .
    1) 2                2) 4                3) 5                4) 6                5) 8
 

 

82. Complete the following reaction:  Sodium chlorate  +   nickel  à  ____________ .

    When the reaction is correctly balanced, what is the coefficient in front of

    sodium chlorate?    1) 1                 2) 2                 3) 3                   4) 4                 5) 5

 

83. Complete the reaction:  zinc hydrogen carbonate  +  ammonium phosphate  à 

      ________ .   When this reaction is properly balanced, what is the coefficient in front

      of  zinc hydrogen carbonate?      l) 1             2) 2             3) 3             4) 4             5) 5

 

84. Complete and balance the reaction:  chromium (III)  oxide  à ________________ .

      What is the coefficient in front of chromium (III) oxide?

     1) 7                  2) 5                  3) 4                  4) 3                   5) 2

 

85. Complete and balance the reaction:  magnesium  +  hydrogen phosphate  à 

      __________ .   What is the coefficient in front of  magnesium?

      1) 6                2) 5                3) 4                4) 3                5) 2

 

86. Complete and balance the following reaction.

    __________________  à  silver sulfate  +  ferric iodide.  What is the coefficient in

    front of silver sulfate?       l) 1              2) 2              3) 3              4) 4              5) 5

 

87. Complete and balance the following reaction.

    __________________  à  aluminum  +  bromine.  What is the coefficient in front of

    bromine?      l) 5               2) 4               3) 3               4) 2               5) 1

 

88. What does X stand for in the following balanced chemical reaction?

    Aluminum sulfate  +  calcium hydroxide  à  ____X____  +  calcium sulfate.

    1)  Al             2) 2 Al             3) Al(OH)₃             4) 2 Al(OH)₃             5) none of these

 

89. Complete and balance the following chemical reaction:

     ___X___  +  oxygen   à  aluminum oxide.  What is represented by X in this reaction?

   1) 4 Al              2) X₂O              3) Al              4) Al₃O₂              5) none of these

 

90. What does X stand for in the following balanced chemical reaction?

   Zinc  +  __X___  à  zinc sulfate  +  hydrogen. 

   1) H₂              2) H₂O              3) SO₂              4) H₂SO₄             5) none of these

 

91. When this reaction is properly balanced, what is the coefficient in front of aluminum?

   Aluminum  + zinc hydrogen carbonate  à  __________________________ .

   1) 1                 2) 2               3) 3                4) 4                5) 6

 

92. When the following reaction is correctly balanced, identify the coefficient in front

   of ammonium sulfide.  Calcium phosphate  +  ammonium sulfate  à  ____________

   1) 1                2) 2                3) 3                4) 4                5) 6

 

93. Complete and balance the following chemical reaction.

   Copper (II) sulfate  +  iron (III) hydroxide  à  _____________ . What is the coefficient

   in front of copper (II) sulfate?      l) 1             2) 2             3) 3              4) 5             5) 6

 

94. Complete and balance the following chemical reaction.

   ______________  à  magnesium phosphate  +  hydrogen.  What is the coefficient in

   front of magnesium phosphate?      l) 1            2) 2            3) 3            4) 4            5) 5

 

95. Balance the equation:  Zn₃As₂  reacts with hydrogen chloride to produce AsH₃ and

   zinc chloride.  What is the coefficient in front of hydrogen chloride?

   1) 7                2) 6                3) 5                4) 4                5) 3

 

96. Balance the equation:  potassium hydroxide  +  aluminum hydroxide  yield  K₃AlO₃

   and water.  What is the coefficient in front of water?

   1) 7                2) 5                3) 4                4) 3                5) none of these

 

97. When the following chemical reaction is balanced with lowest coefficients,

   what is the sum of these coefficients?   HC1  +  Zn₃As₂  à  ____________
   1) 6                2) 11                3) 12                4) 14               5) 16

 

98. This is a complete combustion reaction. Balance and get the sum of the coefficients

    in this equation:  C₃H₄  +  oxygen   à  _______________ .

    1) 8               2) 9                3) 10                4) 11               5) 14

 

99. If nitrogen gas reacts with lithium to produce only lithium nitride, Li₃N,

    the sum of the coefficients in the balanced equation is:
    1) 5;                2) 6;                3) 7;                 4) 8;                5) 9.

100. What is the sum of the coefficients in the following reaction after it is balanced?

                iron III nitrate + sodium sulfide   à  ____________ .

    1) 8                2) 11                3) 12                4) 13                5) none of these

 

101. Balance the half reaction below and then determine the sum of its coefficients.

    ferric phosphate  +  chromium  à  __________ .

    1) 4                 2) 5                3) 6                  4) 7                 5) 9

 

102. The sum of the coefficients for the equation  _____ +  H₂SO₄  à  Al₂SO₄  +  H₂

    should be      1) 9;              2) 7;              3) 11;              4) 8;               5) 5.

 

103. Starting with one mole of FeCl₃, what is the sum of the coefficients in the balanced

    equation FeC1₃   +  KOH  à  _____________ ?
    1) 4                 2) 6                 3) 8                 4) 11                5) 13

 

104. Complete the following reaction. Balance it. Then, add up the coefficients.

    What is your total?   Chromium  +  bromine  à  ____________ . 

    1) 3                 2) 5                 3) 6                 4) 7                 5) none of these

 

105. This is a complete combustion reaction. Balance and find the sum of the

   coefficients in this equation.    C₃H₈  +  oxygen  à  ____________ .

   1) 9                2) 13              3) 15                4) 16                5) none of these

 

106. What is the sum of the coefficients in the following equation after it is balanced?     

                               diphosphorus  pentoxide  à  ______________ .

    1) 5                 2) 7                3) 8                4) 9                5) 11

 

107. Balance the half-reaction and then determine the sum of its coefficients.

    magnesium oxide  +  aluminum  à  ____________ .

    1) 9                  2) 8                 3) 7                 4) 5                 5) none of these

 

108. When this equation is balanced, add up the coefficients. What is this total?

    aluminum  +  hydrogen iodide  à  __________________ .

    1) 7                 2) 13                 3) 16                 4) 21                 5) none of these

 

109. Fluorine reacts with sodium hydroxide to form sodium fluoride, oxygen and water.

   What is the sum of the coefficients in the balanced equation?

    1) 13                 2) 17                 3) 19                 4) 21                 5) 32
 

 

110. Complete combustion of any hydrocarbon in air produces

   1) CO and H₂;           2) CO and H₂O;           3) CO₂  and H₂;           4) CO₂  and H₂O.

 

 

111. When coal is burned completely, it yields:   

    1) carbon and sulfuric acid;         2) carbon dioxide and water;         3) carbon monoxide

    and lead;          4) carbon and heavy water.

 

112. The complete combustion of ethane, C₂H₆,  produces

    1) C₂H₅OH;              2) CH₃COOH;            3) CO₂  and  H₂;            4) CO₂  and  H₂O.

 

113. C₂H₆  +  O₂  yield  ………….    When the reaction is completed and balanced with

    whole numbered coefficients, the coefficient in the front of O₂  (assume complete

    combustion) is:    1) 2;                2) 3;                3) 5;                4) 7.   

 

 114. How many moles of water are formed when one mole of butane, C₄H₁₀ (g), is burned in

    oxygen?       1) 1 mole       2) 5 moles       3) 8 moles       4) 11.2 moles       5) 22.4 moles     
   

 

115. Write the balanced equation for the complete combustion of benzene, C₆H₆,

   in oxygen.   What is the whole-numbered coefficient in front of oxygen?

   1) 2                2) 6                3) 12                4) 13                5) 15

 

 

116. One mole of substance “X” reacts with one mole of water and produces one mole

   of oxygen and two moles of hydrogen fluoride.  “X”  +  H₂O   à   O₂   +  2 HF.

   Which is the formula for substance “X” ?

   1) F₂                 2) OF₂                 3) O₂F                 4) HOF₂

 

 

117. When 40 grams of mercury are heated with oxygen, the mercury unites with

   3 grams of oxygen to form 43 grams of mercuric oxide.  This reaction illustrates

   1) the fact that elements always combine.          3) the Law of Con­servation of Matter.

   2) a nuclear transformation.                                4) the formation of mixtures.

ANS: 3

 

118. Consider the reaction  CH₄  +  O₂  à  CO₂  +  H₂O.  The number of grams of

   water formed when 32 grams of methane are burned is:

   1) 20 grams;              2) 36grams;              3) 45grams;               4) 72grams.