Materials that are more difficult to magnetize but tend to stay magnetized are called a. natural magnets.
b. temporary magnets.
c. permanent magnets.
d. variable magnets.

When can a theory be modified if a new type of technology allows for new observations that raise new questions? a-immediately, while the questions about the theory are being asked b-after new hypotheses related to the theory are tested in experiments c-only after the new observations disprove all parts of the theory d-while scientists begin to think about how the theory could improve