Help:choose the correct statement plz

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?

Which of the following is not a transverse wave? a) soundb) lightc) radiod) all of thesee) none of these

The frequency of the fundamental of the guitar string is 320 hz. at what speed v do waves move along that string?