Ahydrologist from a government agency tests several samples of water for safety. as part of his examinations, he determines the concentration of lead that is
present in each sample.
which method of expressing concentration should the hydrologist use to describe the concentration of lead in the water?
mass percent
ppm or ppb
volume percent
mass-volume percent

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

Asap time is ! best answer gets compose at least one well-developed paragraph on the following: define the term concurrent powers, and give an example of a concurrent power of government.

When considering gravity acceleration and the force of acceleration, what must be true? a. the direction of acceleration must be perpendicular to the direction of the force. b. the direction of the force and the direction of acceleration must be the same as each other. c. the direction of the force and the direction of acceleration must be opposite of each other. d. the mass of the body must be the same as the acceleration of the body.