April 2017

Avogadro Exam 1988: Part 4

Jean Hein

To celebrate the 30th year of the Avogadro Exam we are reprinting the last ten questions from the first exam held in May 1988. The exam was, and is, aimed at grade 11 chemistry students. Students will be writing the exam in May.

  1. A pH of 1.3 for an aqueous solution corresponds to a hydrogen-ion concentration of about
    1. 20 mol/L  
    2. 1.3 mol/L 
    3. 0.8 mol/L
    4. 0.1 mol/L
    5. 0.05 mol/L           
  1. If 1.00 mol/L NaX solution contains 7.45% solute by mass, what is the atomic or formula mass of X?
    1. 1.71   
    2. 51.5
    3. 74.5
    4. 97.5
    5. 1164                         
  2. Which graph(s) describe(s) qualitatively the behaviour of aqueous sodium sulfate solutions?three graphs showing behaviour of aqueous sodium sulfate solutions
    1. (1) only   
    2. (1) and (2) only 
    3. (1) and (3) only
    4. (2) and (3) only
    5. (1) and (2) and (3)              
  1. Which one of the following pairs of reactants will release hydrogen gas when the reactants are mixed and warmed?
    1. baking soda;  lemon juice
    2. hydrogen peroxide;  iron(III) ions
    3. concentrated potassium  aluminum turnings; hydroxide solution
    4. copper;  concentrated nitric acid
    5. ammonium chloride;  lime

  1. Which process illustrates chemical precipitation?
    1. The conversion of sulfur molecules, S8, to sulfur atoms, S
    2. the reaction between 1.00 mol/L solutions of sodium hydroxide and hydrochloric acid
    3. The slight break-up of acetic acid molecules in water to form hydrated protons and acetate ions
    4. The conversion of sodium atoms to sodium ions
    5. The formation of a solid as sodium chloride and silver nitrate solutions are mixed
  2. Which one of the following does not show any significant hydrogen bonding?  (25 °C,  101 kPa)
    1. H2O       
    2. CH3COOH 
    3. HF
    4. CH3OH
    5. CH4        
  3. Which of the following is the most acidic?
    1. Human saliva    
    2. Human blood plasma
    3. Human urine
    4. Human gastric acid
    5. Cow’s milk
  4. Match each chemical in the left-hand column with the household product in which it is found. Use each entry only once.
(1) ammonia v) bleach
(2) acetic (ethanoic) acid w) soap
(3) sodium hydroxide  x) window cleaner
(4) sodium hypochlorite y) vinegar
(5) sodium stearate  z) drain cleaner
 

The correct matches are:

  1. 1W,  2Y,  3X,  4V,  5Z  
  2. 1X,  2Y,  3Z,  4V,  5W 
  3. 1Z,  2X,  3V,  4Y,  5W
  4. 1X,  2V,  3Y,  4W,  5Z
  5. 1W,  2Y,  3Z,  4V,  5X
  1. Which light photons have the highest energy?
    1. Violet      
    2. Yellow  
    3. Blue
    4. Red
    5. Green      
  2. If the energy of the 2s level (Bohr L-shell) in a hydrogen atom is –E, what is the energy of the 3s level (Bohr M-shell)?
    1. 03 E 
    2. -9/4 E
    3. -4/9 E
    4. -3/2 E
    5. -2/3 E 


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