Convert 209ft/s into km/hr

Ineed the answers for these promblems i have

Based on the concept of the wave-like nature of light, huygens' theory of light postulates that the more light was "bent" by a substance the slower it would move while traversing across that substance. a) deflection b) interference c) refraction d) resonance

Under normal conditions, describe how increasing the temperatures effects the solubility of a typical salt