The ratio of carbon-14 to nitrogen-14 in an artifact is 1:7. Given that the half- life of carbon-14 is 5730 years, how old is the artifact?

a.5730 years
b.17.190years
c.11,460 years
d.22,920 years

Light traveling in water, nwater = 1.33, strikes a plastic block at an angle of incidence of 51.4°; part of the beam is reflected and part is refracted. if the index of refraction of the plastic is 2.0, what is the angle made by the reflected and refracted beams?