Photons with the highest energy have the longest period

Alexander calder's mobiles are an example of motion because it uses forces of wind and water.

What defines the mass number of an isotope? a. the sum of the neutrons and protons b. the sum of the neutrons and electrons c. the number of neutrons d. the number of protons

State one advantage and one disadvantage of using a plane mirrior as a driving mirrior