1. To what class of changes do the following belong? (a) The melting of ice; (b) the souring of milk; (c) the burning of a candle; (d) the explosion of gunpowder; (e) the corrosion of metals. What test question must be applied in each of the above cases?
2. Give two additional examples (a) of chemical changes; (b) of physical changes.
3. Is a chemical change always accompanied by a physical change? Is a physical change always accompanied by a chemical change?
4. Give two or more characteristics of a chemical change.
5. (a) When a given weight of water freezes, does it absorb or evolve heat? (b) When the resulting ice melts, is the total heat change the same or different from that of freezing?
6. Give three examples of each of the following: (a) mechanical mixtures; (b) chemical compounds; (c) elements.
7. Give the derivation of the names of the following elements: thorium, gallium, selenium, uranium. (Consult dictionary.)
8. Give examples of chemical changes which are produced through the agency of heat; of light; of electricity.