1. Identify which of the following as a pure substance or a mixture.
   • (a) salt, NaCl
     
     pure substance mixture

   • (b) air
     
     pure substance mixture

   • (c) brass.
     
     pure substance mixture

   • (d) H₂O
     
     pure substance mixture

   • (e) beer
     
     pure substance mixture

2. Identify which of the following pure substances are elements, and which are compounds
   • (a) mercury
     
     element compound

   • (b) rust, iron oxide
     
     element compound

   • (c) aluminum
     
     element compound

   • (d) tungsten
     
     element compound

   • (e) diamond
     
     element compound

3. Identify which of the following mixtures are homogeneous or heterogeneous.
   • (a) beef vegetable soup
     
     
     homogeneous mixture heterogeneous mixture

   • (b) fog
     
     
     homogeneous mixture heterogeneous mixture

   • (c) water and gasoline
     
     
     homogeneous mixture heterogeneous mixture

   • (d) sugar dissolved in water
     
     
     homogeneous mixture heterogeneous mixture

   • (e) 14 carat gold
     
     
     homogeneous mixture heterogeneous mixture

4. Determine whether each of the following properties is physical or chemical.
   • (a) A block of styrofoam floats on water.
     
     physical property chemical property

   • (b) Sugar becomes caramel when heated above its melting point.
     
     physical property chemical property

   • (c) Iron dissolves in hydrochloric acid and hydrogen gas evolves.
     
     physical property chemical property

   • (d) Lithium metal has a shiny surface. After exposure to air, it becomes dull.
     
     physical property chemical property

   • (e) An iron nail is attracted to a magnet.
     
     physical property chemical property

5. Determine whether each of the following is either a chemical change or a physical change.
   • (a) pure water from seawater
     
     physical change chemical change

   • (b)Electricity is passed through water to produce hydrogen and oxygen gases.
     
     physical change chemical change

   • (c) A white T-shirt is dyed red.
     
     physical change chemical change

   • (d) A wet mop dries in the sun.
     
     physical change chemical change

   • (e) Making ice cube in the freezer.
     
     physical change chemical change

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Chemistry Department
British Columbia Institute of Technology, Burnaby, B.C. Canada.
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