1) Why is copper metal easier to produce than iron metal?

a. Copper is easier to reduce than iron.

b. Copper can be reduced by oxidizing the attached sulfur with oxygen.

c. Iron requires toxic carbon monoxide for the reduction process.

d. All of these are true.

2) All of the following are common uses of halogen compounds EXCEPT:

a. Fertilizers

b. Disinfectant and fumigant

c. Dietary supplement

d. Photography

3) In semiconductors, the energy gap is:

a. between the conduction band and the valence band.

b. larger than the energy gap for insulators.

c. part of the valence band.

d. caused by overlapping bands.