# 2 - MATTER AND ENERGY
- Identify which of the following as a pure substance or a mixture.
- (a) salt, NaCl
- (b) air
- (c) brass.
- (d) H2O
- (e) beer
- Identify which of the following pure substances are elements, and which
- (a) mercury
- (b) rust, iron oxide
- (c) aluminum
- (d) tungsten
- (e) diamond
- Identify which of the following mixtures are homogeneous or heterogeneous.
- (a) beef vegetable soup
- (b) fog
- (c) water and gasoline
- (d) sugar dissolved in water
- (e) 14 carat gold
- Determine whether each of the following properties is physical or chemical.
- (a) A block of styrofoam floats on water.
- (b) Sugar becomes caramel when heated above its melting point.
- (c) Iron dissolves in hydrochloric acid and hydrogen gas evolves.
- (d) Lithium metal has a shiny surface. After exposure to air, it becomes
- (e) An iron nail is attracted to a magnet.
- Determine whether each of the following is either a chemical change or
a physical change.
- (a) pure water from seawater
- (b)Electricity is passed through water to produce hydrogen and oxygen
- (c) A white T-shirt is dyed red.
- (d) A wet mop dries in the sun.
- (e) Making ice cube in the freezer.