Chemistry: Week One (Part 1)

http://chemistry.boisestate.edu/rbanks/inorganic/chemistry/chemistry.htm
Quiz results:

1)
Burning wood: Chemical change
Crushing Rock: Physical change
Dissolving sugar in water: Physical change
Rusting of Iron: chemical change

2)
Milk: Mixture
Table Salt: Mixture
Sugar: Pure substance
Steel: Mixture

3)
d...
(Saw that the answer is b. don't quite get it. How can something be impure but homogenous?

4)
d.