Basics Practice Test - Answer Key

 

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  1. A substance X2Z has the composition (by mass) of 40.0% X and 60.0% Z.  What is the composition (by mass) of the compound XZ2?

    14.3% X
    85.7% Z

     

     
  2. An alkali metal oxide contains 83.0% metal by mass.  Determine the identity of the metal.

    Potassium

     

     

  3. Indicate true or false
    1. 18F-, 21Ne, 23Na+ all have the same number of neutrons – False
    2. 18F-, 21Ne, 23Na+ all have the same number of protons – False
    3. 18F-, 21Ne, 23Na+ all have the same number of electrons – True

       

       

  4. How is an isotope formed?
    1. By adding/subtracting protons
    2. By adding/subtracting electrons
    3. By adding/subtraction neutrons
    4. All of the above
    5. None of the above

       

       

  5. What is the empirical formula for C10H15O5?

    C2H3O

    6.  

     

  6. Calculate the mass percent composition of oxygen in Al2(SO4)3.

    56.1% O (by mass)

     

     

  7. Determine the empirical formula for a compound that is 36.86% N and 63.14% O by mass.

    N2O3

 

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