How do nuclear fusion reactions differ from nuclear fission reactions?
A. Nuclear fusion reactions convert all energy into mass.
B. Nuclear fusion reactions follow the law of conservation of matter.
C. Nuclear fusion reactions form lighter isotopes from heavier isotopes.
D. Nuclear fusion reactions form heavier isotopes from lighter isotopes.

According to social exchange theory, altruistic behaviors benefit the individual who performs them.

In what direction does the medium move relative to the direction of the wave? explain.

Glass is transparent to visibile light under normal conditions; however, at extremely high intensities, glass will absorb most of the light incident upon it. this works through a process known as multiphoton absorption. in this process, several photons are absorbed at the same time. if very intense light whose photons carry 2ev of energy is shined onto a material with a band gap of 4ev, that light can be absorbed through two-photon absorption, because two photons have the right amount of energy to bridge the band gap. what is the minimum number of photons of 800-nm light that are needed to equal or exceed the band gap of fused silica glass