Why do force and weight have same units?

Argon, neon, and xenon are examples of

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?

Contains chemical energy. a. heat b. light c. natural gas