AP  Sample Multiple-Choice Exam Questions
The following multiple-choice questions provide a representative subset of those used in previous AP Examinations in Chemistry.  There are two types of multiple-choice questions on the examination.  The first type of question consists of five lettered headings followed by a list of numbered phrases.  For each numbered phrase, the student is instructed to select the one heading that is most closely related to it.  Each heading may be used once, more than  once, or not at all in each group.
 
Questions1-3 refer to atoms of the following elements.
(A)  Lithium
(B)  Carbon
(C)  Nitrogen
(D)  Oxygen
(E)   Fluorine
1.  In the ground state, have only 1 electron in each of the three p orbitals

2.  Have the smallest atomic radius

3.   Have the smallest value for the first ionization energy

The majority of the multiple-choice questions consists of questions or incomplete statements followed by five suggested answers or completions.  The student is instructed to select the one that is best in each case.
 
4.   Which of the following species is NOT planar?
(A)   CO32-
(B)   NO3-
(C)   ClF3   
(D)   BF3
(E)   PCl3
   
    H  H
     |    |
H-C-C-H
     |    |
    H  H
5.   The hybridization of the carbon atoms in the molecule represents above can be described as
(A)   sp
(B)   sp2
(C)   sp3
(D)   dsp2
(E)   d2sp
 
6.   The half-life of 55Cr is about 2.0 hours. The delivery of a sample of this isotope from the reactor to a certain laboratory requires 12 hours.  About what mass of such material should be shipped in order that 1.0 mg of 55Cr is delivered to the laboratory?
(A)   130 mg
(B)     64 mg
(C)     32 mg
(D)     11 mg
(E)        1.0 mg
   
7.    At constant temperature, the behavior of a sample of a real gas more closely approximates that of an ideal gas as its volume is increased because the
(A)   collisions with the walls of the container become less frequent
(B)   average molecular speed decreases
(C)   molecules have expanded
(D)   average distance between molecules becomes greater
(E)    average molecular kinetic energy decreases
  
8.    A sealed vessel contains 0.200 mol of oxygen gas, 0.100 mol of nitrogen gas, and 0.200 mol of argon gas.  the total pressure of the gas mixture is 5.00 atm.   The partial pressure of the argon is
(A)   0.200 atm  
(B)   0.500 atm
(C)   1.00 atm
(D)   2.00 atm
(E)    5.00 atm

9.    Which of the following accounts for the fact that liquid CO2 is not observed when a piece of solid CO2 (dry ice) is placed on a lab bench?
(A)  The phase diagram for CO2 has no triple point  
(B)  The normal boiling point of CO2 is lower than its normal freezing point
(C)  CO2(s) is a molecular solid
(D)  The critical pressure for CO2 is approximately 1 atm.
(E)   The triple point for CO2 is above 1 atm.
  
10.   If  DG for a certain reaction has a negative value at 298 K, which of the following must be true?
  I.   The reaction is exothermic.
 II.  The reaction occurs spontaneously at 298 K.
III.  The rate of the reaction is fast at 298 K.

(A)   I only
(B)   II only
(C)   I and II only
(D)   II and III only
(E)   I, II and III
   
2 SO2(s)  +  O2(g) ----->  2 SO3(g)
11.   A mixture of gases containing 0.20 mol of SO2 and 0.20 mol of O2 in a 4.0 L flask reacts to form SO3.  If the temperature is 25oC, what is the pressure in the flask after reaction is complete?
(A)    0.4(0.082)(298)    atm
                    4

(B)    0.3(0.082)(298)    atm
                    4

(C)    0.2(0.082)(298)    atm
                    4

(D)    0.2(0.082)(25)    atm
                    4

(E)    0.3(0.082)(25)    atm
                    4
  
12.   A solution prepared by mixing 10 mL of 1 M HCl  and 10 mL of 1.2 M NaOH has a pH of
(A)   0      (B)   1     (C)    7       (D)    13       (E)   14
   
13.    All of the following reactions can be defined as a Lewis acid-base reaction EXCEPT
(A)  Al(OH)3(s)  +  OH-(aq)   ---->  Al(OH)4-(aq)
(B)   Cl2(g)  +  H2O(l)  --->  HOCl(aq)  +  H+(aq)  +  Cl-(aq)
(C)   SnCl4(s)  +  2 Cl-(aq)   ---->  SnCl62-(aq)
(D)   NH4+(g)  +  NH2-(g)   ---->  2 NH3(g)
(E)    H+(aq)  +  NH3(aq)  ---->  NH4+(aq)
  
14.  Which of the following represents a process in which a species is reduced?
(A)  Ca(s) ------>   Ca2+(aq)
(B)   Hg(l)   ----->  Hg22+(aq)
(C)   Fe2+(aq) ----->  Fe3+(aq)
(D)   NO3-(aq) ----> NO(g)
(E)    SO32-(aq) ----- >SO42-(aq)
   
Cd2+(aq)  +  2 e-   <===>  Cd(s)    Eo = -0.41 V
Cu+(aq)  +   e-   <===>     Cu(s)     Eo = +0.52 V
Ag+(aq)   +  e-   <===>     Ag(s)     Eo = +0.80 V

15. Based on the standard electrode potentials given above, which of the following is the strongest reducing agent?
(A)    Cd(s)     (B)    Cd2+(aq)       (C)    Cu(s)      (D)     Ag(s)       (E)    Ag+(aq)   
  
16.   A sample of CaCO3 (molar mass 100. g) was reported as being 30. percent Ca.  Assuming no calcium was present in any impurities, the percent of CaCO3 in the sample is
(A)    30%       (B)   40%        (C)   70%       (D)     75%       (E)    100%
  
2  Al(s)  +  6 HCl(aq) ----->  2 AlCl3(aq)  + 3 H2(g)
17.   According to the reaction represented above, about how many grams of aluminum (atomic mass 27 g) are necessary to produce 0.50 mol of hydrogen gas at 25oC and 1.0 atm?
(A)      1.0 g
(B)      9.0 g
(C)    14 g
(D)    27 g
(E)     56 g
  
__ Cr2O72-(aq) +  __ HNO2(aq) + __ H+(aq) --->  Cr3+(aq) + __ NO3-(aq)  + __ H2O(l)
18.     When the equation for the redox reaction represented above is balanced and all coefficients are reduced to lowest whole-number terms, the coefficient for H2O(l) is
(A)   3      (B)   4      (C)   5      (D)   6       (E)    8
   
19.     Which of the following equations represents the net reaction that occurs when gaseous hydrofluoric acid reacts with solid silicon dioxide?
(A)   2 H+(aq)  +  2 F-(aq)   +  SiO2(s)  ---->  SiOF2(s)  +  H2O(l)
(B)   4 F-(aq)  +  SiO2(s)   -----> SiF4(g)  +  2 O2-(aq)
(C)   4 HF(g)  +  SiO2(s)  ----->  SiF4(g)  +  2 H2O(l)
(D)   4 HF(g)  +  SiO2(s)  ----->  Si(s)  +  2 F2(g)  + 2 H2O(l)
(E)    2 H2F(g)  +  Si2O2(s)  ----->  2 SiF(g)  +  2 H2O(l)
    
20.    The ionization constant for acetic acid is 1.8 X 10-5; that for hydrocyanic acid is 4 X 10-10.  In 0.1 M solutions of sodium acetate and sodium cyanide, it is true that
(A)   [H+]  equals [OH-] in each solution
(B)   [H+]  exceeds [OH-] in each solution
(C)   [H+]  of the soidum acetate solution is less than that of the sodium cyanide solution
(D)   [OH-] of the sodium acetate solution is less than that of the soidum cyanide soluiton
(E)   [OH-] for the two solutions is the same
  
HCl  >  HC2H3O2  > HCN  > H2O  > NH3
21.     Five acids are listed above in the order of decreasing acid strength.  Which of the following reactions must have an equilibrium constant with a value less than 1?
(A)   HCl(aq) + CN-(aq)   <===>  HCN(aq)  +  Cl-(aq) 
(B)   HCl(aq) + H2O(l)  <===>  H3O+(aq)  +  Cl-(aq)
(C)   HC2H3O2(aq)  + OH-(aq) <===>  C2H3O2-(aq) + H2O(l)
(D)   H2O(aq)  + NH2-(aq) <===> NH3(aq)  +  OH-(aq)
(E)    HCN(aq)  +  C2H3O2-(aq)  <===>  HC2H3O2(aq)  +  CN-(aq)
    
Experiment
Initial [X]
(mol L-1)
Initial [Y]
(mol L-1)
Initial Rate of Formation of Z
(mol L-1 min-1)
1
0.10
0.30
4.0 x 10-4
2
0.20
0.60
1.6 x 10-3
3
0.20
0.30
4.0 x 10-4
22.   The data in the table above were obtained for the reaction X + Y --> Z.  which of the following is the rate law for the reaction?
(A)   Rate = k[X]2
(B)   Rate = k[Y]2
(C)   Rate = k[X][Y]
(D)   Rate = k[X]2[Y]
(E)   Rate = k[X][Y]2
  
A  --->  X
23.   The enthalpy change for the reaction represented above is DHT.  This reaction can be broken down into a series of steps as shown in the diagram:

                                   DH2
                         
B-------------------------> C
          DH1     /                                                      \    DH3  
                       
/                                            \
                A ------------------------------------X
                                  DHT

A relationship that must exist among the various enthalpy changes is
(A)  DHT - DH1 - DH2 - DH3 = 0
(B)  DHT + DH1 + DH2 + DH3 = 0
(C)  DH3  - (DH1 + DH2)  = DHT
(D)  DH2 - (DH3 + DH1)  = DHT
(E)  DHT + DH2 = DH1  + DH3
   
24.   What formula would be expected for a binary compound of barium and nitrogen?
(A)   Ba3N2
(B)   Ba2N3
(C)   Ba2N
(D)   BaN2
(E)    BaN
   
25.   All of the following statements about the nitrogen family ofelements are true EXCEPT:
(A)   It contains both metals and nonmetals.
(B)   The electronic configuration of the valence shell of the atom is ns2np3.
(C)   The only oxidation states exhibited by members of this familt are -3, 0, +3, +5.
(D)   The atomic radii increase with increasing atomic number.
(E)    The boiling points increase with increasing atomic number.
   
26.   Of the following organic compounds, which is LEAST soluble in water at 298 K?
(A)  CH3OH,  methanol
(B)  CH3CH2CH2OH,  1-propanol
(C)  C6H14,  hexane
(D)  C6H12O6,  glucose
(E)   CH3COOH, ethanoic (acetic) acid
   
27.  Which of the following salts formas a basic solution when dissolved in water?
(A)   NaCl
(B)   (NH4)2SO4
(C)   CuSO4
(D)   K2CO3
(E)    NH4NO3
  
28.   The molecular mass of a substance can be determined by measuring which of the following?
   I.     Osmotic pressure of a solution of the substance
   II.    Freezing point depression of a solution of the substance
   III.   Density of the gas (vapour) phase of the substance

(A)   I only
(B)   III only
(C)   I and II only
(D)   II and III only
(E)    I, II and III 
  
29.     The table below summarizes the reactions of a certain unknown solution when treated with bases.


__________________Results_________________
Sample
Reagent
Limited Amount
of Reagent
Excess Reagent
I
NaOH(aq)
White precipitate
Precipitate dissolves
II
NH3(aq)
White precipitate
White precipitate
Which of the following metallic ions could be present in the unknown solution?
(A)   Ca2+(aq)   (B)  Zn2+(aq)   (C)  Ni2+(aq)    (D)  Al3+(aq)    (E)  Ag+(aq)
  
               Answers to Multiple-Choice Questions
1 - C
7 - D
13 - B
19 - C
25 - C
2 - E
8 - D
14 - D 20 - D
26 - C
3 - A
9 - E
15 - A 21 - E
27 - D
4 - E
10 - B
16 - D 22 - B
28 - E
5 - C
11 - B
17 - B 23 - A
29 - D
6 - B
12 - D
18 - B
24 - A















 
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